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TMP421C [TI]

±1°C Remote and Local TEMPERATURE SENSOR; 为± 1A ℃的远程和本地温度传感器
TMP421C
型号： TMP421C
厂家： TEXAS INSTRUMENTS    TEXAS INSTRUMENTS
描述：

±1°C Remote and Local TEMPERATURE SENSOR
为± 1A ℃的远程和本地温度传感器

传感器 温度传感器
文件： 总34页 (文件大小：904K)
中文：  中文翻译
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TMP421  
TMP422  
TMP423  
www.ti.com  
SBOS398C –JULY 2007–REVISED MAY 2012  
±1°C Remote and Local TEMPERATURE SENSOR  
Check for Samples: TMP421, TMP422, TMP423  
1
FEATURES  
DESCRIPTION  
The TMP421, TMP422, and TMP423 are remote  
234  
•
SOT23-8 and DSBGA (WCSP) PACKAGES  
±1°C REMOTE DIODE SENSOR (MAX)  
±1.5°C LOCAL TEMPERATURE SENSOR (MAX)  
SERIES RESISTANCE CANCELLATION  
n-FACTOR CORRECTION  
temperature sensor monitors with a built-in local  
temperature sensor. The remote temperature sensor  
diode-connected transistors are typically low-cost,  
NPN- or PNP-type transistors or diodes that are an  
integral part of microcontrollers, microprocessors, or  
FPGAs.  
•
•
•
•
•
•
•
•
TWO-WIRE/ SMBus™ SERIAL INTERFACE  
MULTIPLE INTERFACE ADDRESSES  
DIODE FAULT DETECTION  
Remote accuracy is ±1°C for multiple IC  
manufacturers, with no calibration needed. The two-  
wire serial interface accepts SMBus write byte, read  
byte, send byte, and receive byte commands to  
configure the device.  
RoHS COMPLIANT AND NO Sb/Br  
APPLICATIONS  
The TMP421, TMP422, and TMP423 include series  
resistance cancellation, programmable non-ideality  
factor, wide remote temperature measurement range  
(up to +150°C), and diode fault detection.  
•
PROCESSOR/FPGA TEMPERATURE  
MONITORING  
LCD/ DLP®/LCOS PROJECTORS  
•
•
•
•
The TMP421, TMP422, and TMP423 are all available  
in a SOT23-8 package. The TMP421C is also  
available in a DSBGA (WCSP) package.  
SERVERS  
CENTRAL OFFICE TELECOM EQUIPMENT  
STORAGE AREA NETWORKS (SAN)  
+5V  
TMP421  
TMP422  
TMP423  
8
V+  
1
1
1
7
6
SCL  
SDA  
DXP  
DX1  
DXP1  
DXP2  
SMBus  
Controller  
2
3
4
2
2
DXN  
A1  
DX2  
3
4
3
4
DX3  
DX4  
DXP3  
DXN  
A0  
GND  
5
1 Channel Local  
1 Channel Remote  
1 Channel Local  
2 Channels Remote  
1 Channel Local  
3 Channels Remote  
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of  
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.  
2
3
4
DLP is a registered trademark of Texas Instruments.  
SMBus is a trademark of Intel Corporation.  
All other trademarks are the property of their respective owners.  
PRODUCTION DATA information is current as of publication date.  
Products conform to specifications per the terms of the Texas  
Instruments standard warranty. Production processing does not  
necessarily include testing of all parameters.  
Copyright © 2007–2012, Texas Instruments Incorporated  
 
 
TMP421  
TMP422  
TMP423  
SBOS398C –JULY 2007–REVISED MAY 2012  
www.ti.com  
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with  
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.  
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more  
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.  
PACKAGE INFORMATION(1)  
TWO-WIRE  
ADDRESS  
PACKAGE  
DESIGNATOR  
PACKAGE  
MARKING  
PRODUCT  
DESCRIPTION  
PACKAGE-LEAD  
TMP421  
Single Channel  
Remote Junction  
Temperature Sensor  
100 11xx  
100 11xx  
SOT23-8  
DCN  
YZD  
DACI  
TMP421C  
DSBGA-8  
TMP421  
Dual Channel  
Remote Junction  
Temperature Sensor  
TMP422  
100 11xx  
SOT23-8  
DCN  
DADI  
TMP423A  
TMP423B  
Triple Channel  
Remote Junction  
Temperature Sensor  
100 1100  
100 1101  
SOT23-8  
SOT23-8  
DCN  
DCN  
DAEI  
DAFI  
(1) For the most current package and ordering information see the Package Option Addendum at the end of this document, or see the TI  
web site at www.ti.com.  
ABSOLUTE MAXIMUM RATINGS(1)  
Over operating free-air temperature range, unless otherwise noted.  
TMP421, TMP422, TMP423  
UNIT  
V
Power Supply, VS  
Input Voltage  
+7  
–0.5 to VS + 0.5  
–0.5 to 7  
10  
Pins 1, 2, 3, and 4 only  
Pins 6 and 7 only  
V
V
Input Current  
mA  
°C  
°C  
°C  
V
Operating Temperature Range  
Storage Temperature Range  
Junction Temperature (TJ max)  
–55 to +127  
–60 to +130  
+150  
Human Body Model (HBM)  
3000  
ESD Rating  
Charged Device Model (CDM)  
Machine Model (MM)  
1000  
V
200  
V
(1) Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may  
degrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond  
those specified is not implied.  
2
Submit Documentation Feedback  
Copyright © 2007–2012, Texas Instruments Incorporated  
Product Folder Link(s): TMP421 TMP422 TMP423  
 
 
TMP421  
TMP422  
TMP423  
www.ti.com  
SBOS398C –JULY 2007–REVISED MAY 2012  
ELECTRICAL CHARACTERISTICS: TMP421, TMP422, TMP423  
At TA = –40°C to +125°C and V+ = 2.7V to 5.5V, unless otherwise noted.  
TMP421, TMP422, TMP423  
PARAMETER  
TEMPERATURE ERROR  
CONDITIONS  
MIN  
TYP  
MAX  
UNIT  
Local Temperature Sensor  
TELOCAL  
TA = –40°C to +125°C  
TA = +15°C to +85°C, V+ = 3.3V  
±1.25  
±0.25  
±0.25  
±1  
±2.5  
±1.5  
±1  
°C  
°C  
Remote Temperature Sensor(1)  
TEREMOTE  
TA = +15°C to +85°C, TD = –40°C to +150°C, V+ = 3.3V  
TA = –40°C to +100°C, TD = –40°C to +150°C, V+ = 3.3V  
TA = –40°C to +125°C, TD = –40°C to +150°C  
V+ = 2.7V to 5.5V  
°C  
±3  
°C  
±3  
±5  
°C  
vs Supply (Local/Remote)  
TEMPERATURE MEASUREMENT  
Conversion Time (per channel)  
Resolution  
±0.2  
±0.5  
°C/V  
100  
115  
130  
ms  
Local Temperature Sensor (programmable)  
Remote Temperature Sensor  
Remote Sensor Source Currents  
High  
12  
12  
Bits  
Bits  
Series Resistance 3kΩ Max  
120  
60  
μA  
μA  
μA  
μA  
Medium High  
Medium Low  
12  
Low  
6
Remote Transistor Ideality Factor  
SMBus INTERFACE  
η
TMP421/22/23 Optimized Ideality Factor  
1.008  
Logic Input High Voltage (SCL, SDA)  
Logic Input Low Voltage (SCL, SDA)  
Hysteresis  
VIH  
VIL  
2.1  
V
V
0.8  
500  
0.15  
3
mV  
mA  
V
SMBus Output Low Sink Current  
SDA Output Low Voltage  
Logic Input Current  
6
VOL  
IOUT = 6mA  
0.4  
+1  
0 ≤ VIN ≤ 6V  
–1  
μA  
pF  
MHz  
ms  
μs  
SMBus Input Capacitance (SCL, SDA)  
SMBus Clock Frequency  
SMBus Timeout  
3.4  
35  
1
25  
30  
SCL Falling Edge to SDA Valid Time  
DIGITAL INPUTS  
Input Capacitance  
3
pF  
Input Logic Levels  
Input High Voltage  
VIH  
VIL  
IIN  
0.7(V+)  
–0.5  
(V+)+0.5  
0.3(V+)  
1
V
V
Input Low Voltage  
Leakage Input Current  
POWER SUPPLY  
0V ≤ VIN ≤ V+  
μA  
Specified Voltage Range  
Quiescent Current  
V+  
IQ  
2.7  
5.5  
38  
V
0.0625 Conversions per Second  
Eight Conversions per Second  
32  
400  
3
μA  
μA  
μA  
μA  
μA  
V
525  
10  
Serial Bus Inactive, Shutdown Mode  
Serial Bus Active, fS = 400kHz, Shutdown Mode  
Serial Bus Active, fS = 3.4MHz, Shutdown Mode  
90  
350  
2.4  
1.6  
Undervoltage Lockout  
Power-On Reset Threshold  
TEMPERATURE RANGE  
Specified Range  
UVLO  
POR  
2.3  
2.6  
2.3  
V
–40  
–60  
+125  
+130  
°C  
°C  
Storage Range  
Thermal Resistance  
θJA  
SOT23  
100  
°C/W  
(1) Tested with less than 5Ω effective series resistance and 100pF differential input capacitance.  
Copyright © 2007–2012, Texas Instruments Incorporated  
Submit Documentation Feedback  
3
Product Folder Link(s): TMP421 TMP422 TMP423  
TMP421  
TMP422  
TMP423  
SBOS398C –JULY 2007–REVISED MAY 2012  
www.ti.com  
ELECTRICAL CHARACTERISTICS: TMP421C  
At TA = –40°C to +125°C and V+ = 2.55V to 5.5V, unless otherwise noted.  
TMP421C  
TYP  
PARAMETER  
TEMPERATURE ERROR  
CONDITIONS  
MIN  
MAX  
UNIT  
Local Temperature Sensor  
TELOCAL  
TA = –40°C to +125°C  
TA = +15°C to +85°C, V+ = 3.3V  
±1.25  
±0.25  
±0.25  
±1  
±2.5  
±1.5  
±1  
°C  
°C  
Remote Temperature Sensor(1)  
TEREMOTE  
TA = +15°C to +85°C, TD = –40°C to +150°C, V+ = 3.3V  
TA = –40°C to +100°C, TD = –40°C to +150°C, V+ = 3.3V  
TA = –40°C to +125°C, TD = –40°C to +150°C  
V+ = 2.55V to 5.5V  
°C  
±3  
°C  
±3  
±5  
°C  
vs Supply (Local/Remote)  
TEMPERATURE MEASUREMENT  
Conversion Time (per channel)  
Resolution  
±0.2  
±0.5  
°C/V  
100  
115  
130  
ms  
Local Temperature Sensor (programmable)  
Remote Temperature Sensor  
Remote Sensor Source Currents  
High  
12  
12  
Bits  
Bits  
Series Resistance 3kΩ Max  
120  
60  
μA  
μA  
μA  
μA  
Medium High  
Medium Low  
12  
Low  
6
Remote Transistor Ideality Factor  
SMBus INTERFACE  
η
TMP421C Optimized Ideality Factor  
1.008  
Logic Input High Voltage (SCL, SDA)  
Logic Input Low Voltage (SCL, SDA)  
Hysteresis  
VIH  
VIL  
2.1  
V
V
0.8  
500  
0.15  
3
mV  
mA  
V
SMBus Output Low Sink Current  
SDA Output Low Voltage  
Logic Input Current  
6
VOL  
IOUT = 6mA  
0.4  
+1  
0 ≤ VIN ≤ 6V  
–1  
μA  
pF  
MHz  
ms  
μs  
SMBus Input Capacitance (SCL, SDA)  
SMBus Clock Frequency  
SMBus Timeout  
3.4  
35  
1
25  
30  
SCL Falling Edge to SDA Valid Time  
DIGITAL INPUTS  
Input Capacitance  
3
pF  
Input Logic Levels  
Input High Voltage  
VIH  
VIL  
IIN  
0.7(V+)  
–0.5  
(V+)+0.5  
0.3(V+)  
1
V
V
Input Low Voltage  
Leakage Input Current  
POWER SUPPLY  
0V ≤ VIN ≤ V+  
μA  
Specified Voltage Range  
Quiescent Current  
V+  
IQ  
2.55  
5.5  
38  
V
0.0625 Conversions per Second  
Eight Conversions per Second  
32  
400  
3
μA  
μA  
μA  
μA  
μA  
V
525  
10  
Serial Bus Inactive, Shutdown Mode  
Serial Bus Active, fS = 400kHz, Shutdown Mode  
Serial Bus Active, fS = 3.4MHz, Shutdown Mode  
90  
350  
2.4  
1.6  
Undervoltage Lockout  
Power-On Reset Threshold  
TEMPERATURE RANGE  
Specified Range  
UVLO  
POR  
2.3  
2.5  
2.3  
V
–40  
–60  
+125  
+130  
°C  
°C  
Storage Range  
Thermal Resistance  
θJA  
DSBGA  
128  
°C/W  
(1) Tested with less than 5Ω effective series resistance and 100pF differential input capacitance.  
Submit Documentation Feedback  
4
Copyright © 2007–2012, Texas Instruments Incorporated  
Product Folder Link(s): TMP421 TMP422 TMP423  
 
TMP421  
TMP422  
TMP423  
www.ti.com  
SBOS398C –JULY 2007–REVISED MAY 2012  
TMP421 PIN CONFIGURATION  
DCN PACKAGE  
SOT23-8  
(TOP VIEW)  
YZD PACKAGE  
DSBGA-8  
(TOP VIEW)  
V+  
DXP  
DXN  
A1  
1
2
3
4
8
7
6
5
1
2
3
4
8
7
6
5
V+  
DXP  
DXN  
A1  
SCL  
SCL  
SDA  
GND  
TMP421  
SDA  
GND  
A0  
A0  
TMP421 PIN ASSIGNMENTS  
TMP421  
NO.  
1
NAME  
DXP  
DXN  
A1  
DESCRIPTION  
Positive connection to remote temperature sensor.  
2
Negative connection to remote temperature sensor.  
3
Address pin  
4
A0  
Address pin  
5
GND  
SDA  
SCL  
V+  
Ground  
6
Serial data line for SMBus, open-drain; requires pull-up resistor to V+.  
Serial clock line for SMBus, open-drain; requires pull-up resistor to V+.  
7
8
Positive supply voltage (2.7V to 5.5V for the TMP421; 2.55V to 5.5V for the TMP421C)  
TMP422 PIN CONFIGURATION  
DCN PACKAGE  
SOT23-8  
(TOP VIEW)  
V+  
DX1  
DX2  
DX3  
DX4  
1
2
3
4
8
7
6
5
SCL  
TMP422  
SDA  
GND  
TMP422 PIN ASSIGNMENTS  
TMP422  
NO.  
1
NAME  
DX1  
DX2  
DX3  
DX4  
GND  
SDA  
SCL  
V+  
DESCRIPTION  
Channel 1 remote temperature sensor connection pin. Also sets the TMP422 address; see Table 10.  
Channel 1 remote temperature sensor connection pin. Also sets the TMP422 address; see Table 10.  
Channel 2 remote temperature sensor connection pin. Also sets the TMP422 address; see Table 10.  
Channel 2 remote temperature sensor connection pin. Also sets the TMP422 address; see Table 10.  
Ground  
2
3
4
5
6
Serial data line for SMBus, open-drain; requires pull-up resistor to V+.  
Serial clock line for SMBus, open-drain; requires pull-up resistor to V+.  
Positive supply voltage (2.7V to 5.5V)  
7
8
Copyright © 2007–2012, Texas Instruments Incorporated  
Submit Documentation Feedback  
5
Product Folder Link(s): TMP421 TMP422 TMP423  
 
 
TMP421  
TMP422  
TMP423  
SBOS398C –JULY 2007–REVISED MAY 2012  
www.ti.com  
TMP423 PIN CONFIGURATION  
DCN PACKAGE  
SOT23-8  
(TOP VIEW)  
V+  
DXP1  
DXP2  
DXP3  
DXN  
1
2
3
4
8
7
6
5
SCL  
TMP423  
SDA  
GND  
TMP423 PIN ASSIGNMENTS  
TMP423  
NO.  
1
NAME  
DXP1  
DXP2  
DXP3  
DXN  
GND  
SDA  
DESCRIPTION  
Channel 1 positive connection to remote temperature sensor.  
Channel 2 positive connection to remote temperature sensor.  
Channel 3 positive connection to remote temperature sensor.  
Common negative connection to remote temperature sensors, Channel 1, Channel 2, Channel 3.  
Ground  
2
3
4
5
6
Serial data line for SMBus, open-drain; requires pull-up resistor to V+.  
Serial clock line for SMBus, open-drain; requires pull-up resistor to V+.  
Positive supply voltage (2.7V to 5.5V)  
7
SCL  
8
V+  
6
Submit Documentation Feedback  
Copyright © 2007–2012, Texas Instruments Incorporated  
Product Folder Link(s): TMP421 TMP422 TMP423  
 
TMP421  
TMP422  
TMP423  
www.ti.com  
SBOS398C –JULY 2007–REVISED MAY 2012  
TYPICAL CHARACTERISTICS  
At TA = +25°C and V+ = +5.0V, unless otherwise noted.  
REMOTE TEMPERATURE ERROR  
vs TEMPERATURE  
LOCAL TEMPERATURE ERROR  
vs TEMPERATURE  
3
2
3
2
V+ = 3.3V  
50 Units Shown  
V+ = 3.3V  
TREMOTE = +25°C  
30 Typical Units Shown  
h = 1.008  
1
1
0
0
-1  
-2  
-3  
-1  
-2  
-3  
-50  
-25  
0
25  
50  
75  
100  
125  
-50  
-25  
0
25  
50  
75  
100  
125  
Ambient Temperature, TA (°C)  
Ambient Temperature, TA (°C)  
Figure 1.  
Figure 2.  
REMOTE TEMPERATURE ERROR  
vs SERIES RESISTANCE  
(Diode-Connected Transistor, 2N3906 PNP)  
REMOTE TEMPERATURE ERROR  
vs LEAKAGE RESISTANCE  
2.0  
1.5  
60  
40  
V+ = 2.7V  
1.0  
20  
0.5  
R - GND  
R - V+  
0
0
V+ = 5.5V  
-0.5  
-1.0  
-1.5  
-2.0  
-20  
-40  
-60  
0
5
10  
15  
20  
25  
30  
0
500  
1000  
1500  
2000  
2500  
3000  
3500  
Leakage Resistance (MW)  
RS (W)  
Figure 3.  
Figure 4.  
Copyright © 2007–2012, Texas Instruments Incorporated  
Submit Documentation Feedback  
7
Product Folder Link(s): TMP421 TMP422 TMP423  
 
TMP421  
TMP422  
TMP423  
SBOS398C –JULY 2007–REVISED MAY 2012  
www.ti.com  
TYPICAL CHARACTERISTICS (continued)  
At TA = +25°C and V+ = +5.0V, unless otherwise noted.  
REMOTE TEMPERATURE ERROR  
vs SERIES RESISTANCE  
(GND Collector-Connected Transistor, 2N3906 PNP)  
REMOTE TEMPERATURE ERROR  
vs DIFFERENTIAL CAPACITANCE  
2.0  
3
2
1.5  
V+ = 2.7V  
1.0  
1
0.5  
V+ = 5.5V  
0
0
-0.5  
-1.0  
-1.5  
-2.0  
-1  
-2  
-3  
0
0.5  
1.0  
1.5  
2.0  
2.5  
3.0  
0
500  
1000  
1500  
2000  
2500  
3000  
3500  
Capacitance (nF)  
RS (W)  
Figure 5.  
Figure 6.  
TEMPERATURE ERROR  
vs POWER-SUPPLY NOISE FREQUENCY  
QUIESCENT CURRENT  
vs CONVERSION RATE  
25  
20  
500  
450  
400  
350  
300  
250  
200  
150  
100  
50  
Local 100mVPP Noise  
Remote 100mVPP Noise  
Local 250mVPP Noise  
Remote 250mVPP Noise  
15  
10  
5
V+ = 5.5V  
0
-5  
-10  
-15  
-20  
-25  
V+ = 2.7V  
0
0.0625 0.125 0.25  
0
5
10  
15  
0.5  
1
2
4
8
Frequency (MHz)  
Conversion Rate (conversions/sec)  
Figure 7.  
Figure 8.  
SHUTDOWN QUIESCENT CURRENT  
vs SCL CLOCK FREQUENCY  
SHUTDOWN QUIESCENT CURRENT  
vs SUPPLY VOLTAGE  
500  
450  
400  
350  
300  
250  
200  
150  
100  
50  
8
7
6
5
4
3
2
1
0
V+ = 5.5V  
V+ = 3.3V  
1M 10M  
0
1k  
10k  
100k  
2.5  
3.0  
3.5  
4.0  
4.5  
5.0  
5.5  
SCL CLock Frequency (Hz)  
V+ (V)  
Figure 9.  
Figure 10.  
8
Submit Documentation Feedback  
Copyright © 2007–2012, Texas Instruments Incorporated  
Product Folder Link(s): TMP421 TMP422 TMP423  
 
 
 
TMP421  
TMP422  
TMP423  
www.ti.com  
SBOS398C –JULY 2007–REVISED MAY 2012  
APPLICATION INFORMATION  
The TMP421 is a two-channel digital temperature  
For proper remote temperature sensing operation, the  
TMP421 requires only transistor connected  
between DXP and DXN pins. If the remote channel is  
not utilized, DXP can be left open or tied to GND.  
sensor that combines  
measurement channel and  
a
local die temperature-  
remote-junction  
a
a
temperature-measurement channel, and is available  
in SOT23-8 and DSBGA-8 packages. The TMP422  
(three-channel), and TMP423 (four-channel) are  
digital temperature sensors that combine a local die  
temperature measurement channel and two or three  
remote junction temperature measurement channels,  
respectively, in a single SOT23-8 package. These  
devices are two-wire- and SMBus interface-  
compatible and are specified over a temperature  
range of –40°C to +125°C. The TMP421/22/23 each  
contain multiple registers for holding configuration  
information and temperature measurement results.  
The TMP422 requires transistors connected between  
DX1 and DX2 and between DX3 and DX4. Unused  
channels on the TMP422 must be connected to GND.  
The TMP423 requires a transistor connected to each  
positive channel (DXP1, DXP2, and DXP3), with the  
base of each channel tied to the common negative,  
DXN. For an unused channel, the TMP423 DXP pin  
can be left open or tied to GND.  
The TMP421/22/23 SCL and SDA interface pins each  
require pull-up resistors as part of the communication  
bus. A 0.1μF power-supply bypass capacitor is  
recommended for local bypassing. Figure 11,  
Figure 12, and Figure 13 show typical configurations  
for the TMP421, TMP422, and TMP423, respectively.  
+5V  
Transistor-connected configuration(1)  
:
0.1mF  
10kW  
(typ)  
10kW  
(typ)  
Series Resistance  
(2)  
RS  
8
V+  
7
6
1
2
SCL  
SDA  
DXP  
(3)  
SMBus  
Controller  
(2)  
CDIFF  
RS  
DXN  
A1  
TMP421  
3
4
A0  
GND  
5
Diode-connected configuration(1)  
(2)  
RS  
:
(3)  
(2)  
CDIFF  
RS  
(1) Diode-connected configuration provides better settling time. Transistor-connected configuration provides better series resistance  
cancellation.  
(2) RS (optional) should be < 1.5kΩ in most applications. Selection of RS depends on application; see the Filtering section.  
(3) CDIFF (optional) should be < 1000pF in most applications. Selection of CDIFF depends on application; see the Filtering section and  
Figure 6, Remote Temperature Error vs Differential Capacitance.  
Figure 11. TMP421 Basic Connections  
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+5V  
Transistor-connected configuration(1)  
:
0.1mF  
10kW  
(typ)  
10kW  
(typ)  
Series Resistance  
(2)  
RS  
8
V+  
7
6
1
2
DX1(4)  
DX2(4)  
SCL  
SDA  
DXP1  
DXP2  
(3)  
(2)  
SMBus  
Controller  
CDIFF  
RS  
DXN1  
DXN2  
(2)  
TMP422  
RS  
RS  
3
4
DX3(4)  
DX4(4)  
(3)  
(2)  
CDIFF  
GND  
5
Diode-connected configuration(1)  
:
(2)  
RS  
(3)  
(2)  
CDIFF  
RS  
(1) Diode-connected configuration provides better settling time. Transistor-connected configuration provides better series resistance  
cancellation.  
(2) RS (optional) should be < 1.5kΩ in most applications. Selection of RS depends on application; see the Filtering section.  
(3) CDIFF (optional) should be < 1000pF in most applications. Selection of CDIFF depends on application; see the Filtering section and  
Figure 6, Remote Temperature Error vs Differential Capacitance.  
(4) TMP422 SMBus slave address is 1001 100 when connected as shown.  
Figure 12. TMP422 Basic Connections  
+5V  
Transistor-connected configuration(1)  
Series Resistance  
(2)  
:
10k  
(typ)  
10k  
(typ)  
0.1mF  
8
RS  
V+  
1
7
6
DXP1  
DXP2  
SCL  
SDA  
(2)  
(3)  
SMBus  
Controller  
RS  
CDIFF  
2
(3)  
CDIFF  
TMP423  
(2)  
RS  
3
4
DXP3  
DXN  
(3)  
(2)  
(2)  
(2)  
CDIFF  
RS  
RS  
RS  
GND  
5
Diode-connected configuration(1)  
(2)  
RS  
:
DXP  
(3)  
(2)  
CDIFF  
RS  
DXN  
(1) Diode-connected configuration provides better settling time. Transistor-connected configuration provides better series resistance  
cancellation.  
(2) RS (optional) should be < 1.5kΩ in most applications. Selection of RS depends on application; see the Filtering section.  
(3) CDIFF (optional) should be < 1000pF in most applications. Selection of CDIFF depends on application; see the Filtering section and  
Figure 6, Remote Temperature Error vs Differential Capacitance.  
Figure 13. TMP423 Basic Connections  
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SERIES RESISTANCE CANCELLATION  
changing bit 2 (RANGE) of Configuration Register 1  
from low to high. The change in measurement range  
and data format from standard binary to extended  
binary occurs at the next temperature conversion. For  
data captured in the extended temperature range  
configuration, an offset of 64 (40h) is added to the  
standard binary value, as shown in the Extended  
Binary column of Table 1. This configuration allows  
measurement of temperatures as low as –64°C, and  
as high as +191°C; however, most temperature-  
sensing diodes only measure with the range of –55°C  
to +150°C. Additionally, the TMP421/22/23 are rated  
only for ambient temperatures ranging from –40°C to  
+125°C. Parameters in the Absolute Maximum  
Ratings table must be observed.  
Series resistance in an application circuit that typically  
results from printed circuit board (PCB) trace  
resistance and remote line length is automatically  
cancelled by the TMP421/22/23, preventing what  
would otherwise result in a temperature offset. A total  
of up to 3kΩ of series line resistance is cancelled by  
the TMP421/22/23, eliminating the need for additional  
characterization and temperature offset correction.  
See the two Remote Temperature Error vs Series  
Resistance typical characteristic curves (Figure 4 and  
Figure 5) for details on the effects of series resistance  
and power-supply voltage on sensed remote  
temperature error.  
DIFFERENTIAL INPUT CAPACITANCE  
Table 1. Temperature Data Format (Local and  
Remote Temperature High Bytes)  
The TMP421/22/23 tolerate differential input  
capacitance of up to 1000pF with minimal change in  
temperature error. The effect of capacitance on  
sensed remote temperature error is illustrated in  
Figure 6, Remote Temperature Error vs Differential  
Capacitance.  
LOCAL/REMOTE TEMPERATURE REGISTER  
HIGH BYTE VALUE (1°C RESOLUTION)  
STANDARD BINARY(1)  
EXTENDED BINARY(2)  
TEMP  
(°C)  
BINARY  
HEX  
C0  
CE  
E7  
00  
BINARY  
HEX  
00  
–64  
–50  
–25  
0
1100 0000  
1100 1110  
1110 0111  
0000 0000  
0000 0001  
0000 0101  
0000 1010  
0001 1001  
0011 0010  
0100 1011  
0110 0100  
0111 1101  
0111 1111  
0111 1111  
0111 1111  
0111 1111  
0000 0000  
0000 1110  
0010 0111  
0100 0000  
0100 0001  
0100 0101  
0100 1010  
0101 1001  
0111 0010  
1000 1011  
1010 0100  
1011 1101  
1011 1111  
1101 0110  
1110 1111  
1111 1111  
0E  
27  
TEMPERATURE MEASUREMENT DATA  
40  
Temperature measurement data may be taken over  
an operating range of –40°C to +127°C for both local  
and remote locations.  
1
01  
41  
5
05  
45  
10  
0A  
19  
4A  
59  
However, measurements from –55°C to +150°C can  
be made both locally and remotely by reconfiguring  
the TMP421/22/23 for the extended temperature  
range, as described below.  
25  
50  
32  
72  
75  
4B  
64  
8B  
A4  
BD  
BF  
D6  
EF  
FF  
100  
125  
127  
150  
175  
191  
Temperature data that result from conversions within  
the default measurement range are represented in  
binary form, as shown in Table 1, Standard Binary  
column. Note that although the device is rated to only  
measure temperatures down to –55°C, it may read  
temperatures below this level. However, any  
temperature below –64°C results in a data value of  
–64 (C0h). Likewise, temperatures above +127°C  
result in a value of 127 (7Fh). The device can be set  
to measure over an extended temperature range by  
7D  
7F  
7F  
7F  
7F  
(1) Resolution is 1°C/count. Negative numbers are represented in  
two's complement format.  
(2) Resolution is 1°C/count. All values are unsigned with a –64°C  
offset.  
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Standard Decimal to Binary Temperature Data  
Both local and remote temperature data use two  
bytes for data storage. The high byte stores the  
temperature with 1°C resolution. The second or low  
byte stores the decimal fraction value of the  
Calculation Example  
For positive temperatures (for example, +20°C):  
(+20°C)/(+1°C/count) = 20 → 14h → 0001 0100  
temperature and allows  
a higher measurement  
Convert the number to binary code with 8-bit,  
right-justified format, and MSB = '0' to denote a  
positive sign.  
resolution, as shown in Table 2. The measurement  
resolution for the both the local and remote channels  
is 0.0625°C, and is not adjustable.  
+20°C is stored as 0001 0100 → 14h.  
Table 2. Decimal Fraction Temperature Data  
Format (Local and Remote Temperature Low  
Bytes)  
For negative temperatures (for example, –20°C):  
(|–20|)/(+1°C/count) = 20 → 14h → 0001 0100  
Generate the two's complement of a negative  
number by complementing the absolute value  
binary number and adding 1.  
TEMPERATURE REGISTER LOW BYTE VALUE  
(0.0625°C RESOLUTION)(1)  
TEMP  
(°C)  
STANDARD AND EXTENDED BINARY  
0000 0000  
HEX  
00  
10  
20  
30  
40  
50  
60  
70  
80  
90  
A0  
B0  
C0  
D0  
E0  
F0  
0
–20°C is stored as 1110 1100 → ECh.  
0.0625  
0.1250  
0.1875  
0.2500  
0.3125  
0.3750  
0.4375  
0.5000  
0.5625  
0.6250  
0.6875  
0.7500  
0.8125  
0.8750  
0.9385  
0001 0000  
REGISTER INFORMATION  
0010 0000  
0011 0000  
The TMP421/22/23 contain multiple registers for  
holding configuration information, temperature  
measurement results, and status information. These  
registers are described in Figure 14 and Table 3.  
0100 0000  
0101 0000  
0110 0000  
0111 0000  
POINTER REGISTER  
1000 0000  
1001 0000  
Figure 14 shows the internal register structure of the  
TMP421/22/23. The 8-bit Pointer Register is used to  
address a given data register. The Pointer Register  
identifies which of the data registers should respond  
to a read or write command on the two-wire bus. This  
register is set with every write command. A write  
command must be issued to set the proper value in  
1010 0000  
1011 0000  
1100 0000  
1101 0000  
1110 0000  
1111 0000  
the Pointer Register before executing  
a read  
(1) Resolution is 0.0625°C/count. All possible values are shown.  
command. Table 3 describes the pointer address of  
the TMP421/22/23 registers. The power-on reset  
(POR) value of the Pointer Register is 00h (0000  
0000b).  
Standard Binary to Decimal Temperature Data  
Calculation Example  
High byte conversion (for example, 0111 0011):  
Pointer Register  
Convert the right-justified binary high byte to  
hexadecimal.  
Local and Remote Temperature Registers  
From hexadecimal, multiply the first number by  
160 = 1 and the second number by 161 = 16.  
Status Register  
SDA  
Configuration Registers  
The sum equals the decimal equivalent.  
0111 0011b → 73h → (3 × 160) + (7 × 161) = 115  
One-Shot Start Register  
Conversion Rate Register  
N-Factor Correction Registers  
Identification Registers  
Software Reset  
I/O  
Control  
Interface  
Low byte conversion (for example, 0111 0000):  
To convert the left-justified binary low-byte to  
decimal, use bits 7 through 4 and ignore bits 3  
through 0 because they do not affect the value of  
the number.  
SCL  
0111b → (0 × 1/2)1 + (1 × 1/2)2 + (1 × 1/2)3 + (1  
× 1/2)4 = 0.4375  
Figure 14. Internal Register Structure  
Note that the final numerical result is the sum of the  
high byte and low byte. In negative temperatures, the  
unsigned low byte adds to the negative high byte to  
result in a value less than the high byte (for instance,  
–15 + 0.75 = –14.25, not –15.75).  
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Table 3. Register Map  
BIT DESCRIPTION  
POINTER  
(HEX)  
POR (HEX)  
7
6
5
4
3
2
1
0
REGISTER DESCRIPTION  
(1)  
00  
01  
00  
LT11  
LT10  
LT9  
LT8  
LT7  
LT6  
LT5  
LT4  
Local Temperature (High Byte)  
Remote Temperature 1  
(High Byte)(1)  
00  
00  
00  
RT11  
RT11  
RT11  
RT10  
RT10  
RT10  
RT9  
RT9  
RT9  
RT8  
RT8  
RT8  
RT7  
RT7  
RT7  
RT6  
RT6  
RT6  
RT5  
RT5  
RT5  
RT4  
RT4  
RT4  
Remote Temperature 2  
02  
03  
(2) (3)  
(High Byte)(1)  
Remote Temperature 3  
(3)  
(High Byte)(1)  
08  
09  
BUSY  
0
0
0
0
0
0
0
0
0
0
0
0
0
Status Register  
00  
SD  
RANGE  
Configuration Register 1  
1C/3C(2)  
7C(3)  
/
(3)  
0A  
0
REN3(3)  
REN2(2)  
REN  
LEN  
RC  
0
0
Configuration Register 2  
0B  
0F  
10  
11  
07  
0
0
0
0
0
X
0
0
R2  
X
R1  
X
R0  
X
Conversion Rate Register  
One-Shot Start(4)  
X
X
X
X
00  
00  
LT3  
RT3  
LT2  
RT2  
LT1  
RT1  
LT0  
RT0  
0
PVLD  
PVLD  
0
Local Temperature (Low Byte)  
0
OPEN  
Remote Temperature 1 (Low Byte)  
Remote Temperature 2  
12  
00  
RT3  
RT2  
RT1  
RT0  
0
0
PVLD  
OPEN  
(3)  
(Low Byte)(2)  
13  
21  
22  
23  
FC  
FE  
00  
00  
00  
00  
RT3  
NC7  
NC7  
NC7  
X
RT2  
NC6  
NC6  
NC6  
X
RT1  
NC5  
NC5  
NC5  
X
RT0  
NC4  
NC4  
NC4  
X
0
NC3  
NC3  
NC3  
X
0
NC2  
NC2  
NC2  
X
PLVD  
NC1  
NC1  
NC1  
X
OPEN  
NC0  
NC0  
NC0  
X
Remote Temperature 3 (Low Byte)(3)  
N Correction 1  
(3)  
N Correction 2(2)  
N Correction 3(3)  
Software Reset(5)  
Manufacturer ID  
55  
21  
0
1
0
1
0
1
0
1
0
0
1
0
0
0
0
1
TMP421 Device ID  
TMP422 Device ID  
TMP423 Device ID  
FF  
0
0
1
0
0
0
1
0
0
0
1
0
0
0
1
1
(1) Compatible with Two-Byte Read; see Figure 19.  
(2) TMP422.  
(3) TMP423.  
(4) X = undefined. Writing any value to this register initiates a one-shot start; see the One-Shot Conversion section.  
(5) X = undefined. Writing any value to this register initiates a software reset; see the Software Reset section.  
The TMP421/22/23 contain circuitry to assure that a  
TEMPERATURE REGISTERS  
low byte register read command returns data from the  
same ADC conversion as the immediately preceding  
high byte read command. This assurance remains  
valid only until another register is read. For proper  
operation, the high byte of a temperature register  
should be read first. The low byte register should be  
read in the next read command. The low byte register  
may be left unread if the LSBs are not needed.  
Alternatively, the temperature registers may be read  
as a 16-bit register by using a single two-byte read  
command from address 00h for the local channel  
result, or from address 01h for the remote channel  
result (02h for the second remote channel result, and  
03h for the third remote channel). The high byte is  
output first, followed by the low byte. Both bytes of  
this read operation are from the same ADC  
conversion. The power-on reset value of all  
temperature registers is 00h.  
The TMP421/22/23 have multiple 8-bit registers that  
hold temperature measurement results. The local  
channel and each of the remote channels have a high  
byte register that contains the most significant bits  
(MSBs) of the temperature analog-to-digital converter  
(ADC) result and a low byte register that contains the  
least significant bits (LSBs) of the temperature ADC  
result. The local channel high byte address is 00h;  
the local channel low byte address is 10h. The  
remote channel high byte is at address 01h; the  
remote channel low byte address is 11h. For the  
TMP422, the second remote channel high byte  
address is 02h; the second remote channel low byte  
is 12h. The TMP 423 uses the same local and remote  
address as the TMP421 and TMP422, with the third  
remote channel high byte of 03h; the third remote  
channel low byte is 13h. These registers are read-  
only and are updated by the ADC each time a  
temperature measurement is completed.  
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STATUS REGISTER  
shutdown mode. When SD is set to '0' again, the  
TMP421/22/23 resume continuous conversions.  
When SD = '1', a single conversion can be started by  
writing to the One-Shot Register. See the One-Shot  
Conversion section for more information.  
The Status Register reports the state of the  
temperature ADCs. Table 4 summarizes the Status  
Register bits. The Status Register is read-only, and is  
read by accessing pointer address 08h.  
The temperature range is set by configuring the  
RANGE bit (bit 2) of the Configuration Register.  
Setting this bit low configures the TMP421/22/23 for  
the standard measurement range (–40°C to +127°C);  
temperature conversions will be stored in the  
standard binary format. Setting bit 2 high configures  
the TMP421/22/23 for the extended measurement  
range (–55°C to +150°C); temperature conversions  
will be stored in the extended binary format (see  
Table 1).  
The BUSY bit = '1' if the ADC is making a conversion;  
it is set to '0' if the ADC is not converting.  
CONFIGURATION REGISTER 1  
Configuration Register 1 (pointer address 09h) sets  
the temperature range and controls the shutdown  
mode. The Configuration Register is set by writing to  
pointer address 09h and read by reading from pointer  
address 09h. Table  
5 summarizes the bits of  
Configuration Register 1.  
The remaining bits of the Configuration Register are  
reserved and must always be set to '0'. The power-on  
reset value for this register is 00h.  
The shutdown (SD) bit (bit 6) enables or disables the  
temperature measurement circuitry. If SD = '0', the  
TMP421/22/23 convert continuously at the rate set in  
the conversion rate register. When SD is set to '1',  
the TMP421/22/23 stop converting when the current  
CONFIGURATION REGISTER 2  
Configuration Register  
2 (pointer address 0Ah)  
conversion sequence is complete and enter  
a
controls which temperature measurement channels  
are enabled and whether the external channels have  
the resistance correction feature enabled or not.  
Table  
6 summarizes the bits of Configuration  
Register 2.  
Table 4. Status Register Format  
STATUS REGISTER (Read = 08h, Write = NA)  
BIT #  
BIT NAME  
D7  
BUSY  
0(1)  
D6  
0
D5  
0
D4  
0
D3  
0
D2  
0
D1  
0
D0  
0
POR VALUE  
0
0
0
0
0
0
0
(1) FOR TMP421/TMP423: The BUSY changes to '1' almost immediately (< 100μs) following power-up, as the TMP421/TMP423 begin the  
first temperature conversion. It is high whenever the TMP421/TMP423 convert a temperature reading.  
FOR TMP422: The BUSY bit changes to '1' approximately 1ms following power-up. It is high whenever the TMP422 converts a  
temperature reading.  
Table 5. Configuration Register 1 Bit Descriptions  
CONFIGURATION REGISTER 1 (Read/Write = 09h, POR = 00h)  
POWER-ON RESET  
BIT  
NAME  
FUNCTION  
VALUE  
7
Reserved  
—
0
0 = Run  
1 = Shut Down  
6
5, 4, 3  
2
SD  
Reserved  
0
0
0
0
—
0 = –40°C to +127°C  
1 = –55°C to +150°C  
Temperature Range  
Reserved  
1, 0  
—
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The RC bit (bit 2) enables the resistance correction  
feature for the external temperature channels. If RC =  
'1', series resistance correction is enabled; if RC = '0',  
resistance correction is disabled. Resistance  
correction should be enabled for most applications.  
However, disabling the resistance correction may  
yield slightly improved temperature measurement  
noise performance, and reduce conversion time by  
about 50%, which could lower power consumption  
when conversion rates of two per second or less are  
selected.  
For the TMP423 only, the REN3 bit (bit 6) enables  
the third external measurement channel. If REN3 =  
'1', the third external channel is enabled; if REN3 =  
'0', the third external channel is disabled.  
The temperature measurement sequence is: local  
channel, external channel 1, external channel 2,  
external channel 3, shutdown, and delay (to set  
conversion rate, if necessary). The sequence starts  
over with the local channel. If any of the channels are  
disabled, they are bypassed in the sequence.  
The LEN bit (bit 3) enables the local temperature  
measurement channel. If LEN = '1', the local channel  
is enabled; if LEN = '0', the local channel is disabled.  
CONVERSION RATE REGISTER  
The Conversion Rate Register (pointer address 0Bh)  
controls the rate at which temperature conversions  
are performed. This register adjusts the idle time  
between conversions but not the conversion timing  
itself, thereby allowing the TMP421/22/23 power  
dissipation to be balanced with the temperature  
The REN bit (bit 4) enables external temperature  
measurement for channel 1. If REN = '1', the first  
external channel is enabled; if REN = '0', the external  
channel is disabled.  
register update rate. Table  
7
describes the  
For the TMP422 and TMP423 only, the REN2 bit (bit  
5) enables the second external measurement  
channel. If REN2 = '1', the second external channel is  
enabled; if REN2 = '0', the second external channel is  
disabled.  
conversion rate options and corresponding current  
consumption. A one-shot command can be used  
during the idle time between conversions to  
immediately start temperature conversions on all  
enabled channels.  
Table 6. Configuration Register 2 Bit Descriptions  
CONFIGURATION REGISTER 2 (Read/Write = 0Ah, POR = 1Ch for TMP421; 3Ch for TMP422; 7Ch for TMP423)  
POWER-ON RESET  
BIT  
NAME  
FUNCTION  
VALUE  
7
Reserved  
—
0
0 = External Channel 3 Disabled  
1 = External Channel 3 Enabled  
1 (TMP423)  
0 (TMP421, TMP422)  
6
5
4
3
REN3  
REN2  
REN  
0 = External Channel 2 Disabled  
1 = External Channel 2 Enabled  
1 (TMP422, TMP423)  
0 (TMP421)  
0 = External Channel 1 Disabled  
1 = External Channel 1 Enabled  
1
1
0 = Local Channel Disabled  
1 = Local Channel Enabled  
LEN  
0 = Resistance Correction Disabled  
1 = Resistance Correction Enabled  
2
RC  
1
0
1, 0  
Reserved  
—
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Table 7. Conversion Rate Register  
CONVERSION RATE REGISTER (Read/Write = 0Bh, POR = 07h)  
AVERAGE IQ (TYP) (μA)  
R7  
0
R6  
0
R5  
0
R4  
0
R3  
0
R2  
0
R1  
0
R0  
0
CONVERSIONS/SEC  
V+ = 2.7V  
11  
V+ = 5.5V  
32  
0.0625  
0.125  
0.25  
0.5  
0
0
0
0
0
0
0
1
17  
38  
0
0
0
0
0
0
1
0
28  
49  
0
0
0
0
0
0
1
1
47  
69  
0
0
0
0
0
1
0
0
1
80  
103  
155  
220  
413  
0
0
0
0
0
1
0
1
2
128  
190  
373  
0
0
0
0
0
1
1
0
4(1)  
8(2)  
0
0
0
0
0
1
1
1
(1) Conversion rate shown is for only one or two enabled measurement channels. When three channels are enabled, the conversion rate is  
2 and 2/3 conversions-per-second. When four channels are enabled, the conversion rate is 2 per second.  
(2) Conversion rate shown is for only one enabled measurement channel. When two channels are enabled, the conversion rate is 4  
conversions-per-second. When three channels are enabled, the conversion rate is 2 and 2/3 conversions-per-second. When four  
channels are enabled, the conversion rate is 2 conversions-per-second.  
The value η in Equation 1 is a characteristic of the  
ONE-SHOT CONVERSION  
particular transistor used for the remote channel. The  
power-on reset value for the TMP421/22/23 is η =  
1.008. The value in the η-Factor Correction Register  
may be used to adjust the effective η-factor according  
to Equation 2 and Equation 3.  
When the TMP421/22/23 are in shutdown mode  
(SD = 1 in the Configuration Register 1), a single  
conversion is started on all enabled channels by  
writing any value to the One-Shot Start Register,  
pointer address 0Fh. This write operation starts one  
conversion; the TMP421/22/23 return to shutdown  
mode when that conversion completes. The value of  
the data sent in the write command is irrelevant and  
is not stored by the TMP421/22/23. When the  
TMP421/22/23 are in shutdown mode, the conversion  
sequence currently in process must be completed  
before a one-shot command can be issued. One-shot  
commands issued during a conversion are ignored.  
1.008 ´ 300  
heff  
=
300 - NADJUST  
(2)  
300 ´ 1.008  
NADJUST = 300 -  
heff  
(3)  
The η-correction value must be stored in two's-  
complement format, yielding an effective data range  
from –128 to +127. The n-correction value may be  
written to and read from pointer address 21h. The η-  
correction value for the second remote channel  
(TMP422 and TMP423) may be written and read from  
pointer address 22h. The η-correction value for the  
third remote channel (TMP423 only) may be written  
to and read from pointer address 23h. The register  
power-on reset value is 00h, thus having no effect  
unless the register is written to.  
η-FACTOR CORRECTION REGISTER  
The TMP421/22/23 allow for a different η-factor value  
to be used for converting remote channel  
measurements to temperature. The remote channel  
uses sequential current excitation to extract  
a
differential VBE voltage measurement to determine  
the temperature of the remote transistor. Equation 1  
describes this voltage and temperature.  
hkT  
I2  
I1  
VBE2 - VBE1  
=
ln  
q
(1)  
16  
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SOFTWARE RESET  
address FEh. The device ID is obtained by reading  
from pointer address FFh. The TMP421/22/23 each  
return 55h for the manufacturer code. The TMP421  
returns 21h for the device ID; the TMP422 returns  
22h for the device ID; and the TMP423 returns 23h  
for the device ID. These registers are read-only.  
The TMP421/22/23 may be reset by writing any value  
to the Software Reset Register (pointer address  
FCh). This action restores the power-on reset state to  
all of the TMP421/22/23 registers as well as aborts  
any conversion in process. The TMP421/22/23 also  
support reset via the two-wire general call address  
(0000 0000). The General Call Reset section contains  
more information.  
BUS OVERVIEW  
The TMP421/22/23 are SMBus interface-compatible.  
In SMBus protocol, the device that initiates the  
transfer is called a master, and the devices controlled  
by the master are slaves. The bus must be controlled  
by a master device that generates the serial clock  
(SCL), controls the bus access, and generates the  
START and STOP conditions.  
Table 8. η-Factor Range  
NADJUST  
BINARY  
HEX  
7F  
0A  
08  
DECIMAL  
η
0111 1111  
0000 1010  
0000 1000  
0000 0110  
0000 0100  
0000 0010  
0000 0001  
0000 0000  
1111 1111  
1111 1110  
1111 1100  
1111 1010  
1111 1000  
1111 0110  
1000 0000  
127  
10  
8
1.747977  
1.042759  
1.035616  
1.028571  
1.021622  
1.014765  
1.011371  
1.008  
To address a specific device, a START condition is  
initiated. START is indicated by pulling the data line  
(SDA) from a high-to-low logic level while SCL is  
high. All slaves on the bus shift in the slave address  
byte, with the last bit indicating whether a read or  
write operation is intended. During the ninth clock  
pulse, the slave being addressed responds to the  
master by generating an Acknowledge and pulling  
SDA low.  
06  
6
04  
4
02  
2
01  
1
00  
0
FF  
FE  
FC  
FA  
F8  
F6  
80  
–1  
–2  
–4  
–6  
–8  
–10  
–128  
1.004651  
1.001325  
0.994737  
0.988235  
0.981818  
0.975484  
0.706542  
Data transfer is then initiated and sent over eight  
clock pulses followed by an Acknowledge bit. During  
data transfer SDA must remain stable while SCL is  
high, because any change in SDA while SCL is high  
is interpreted as a control signal.  
Once all data have been transferred, the master  
generates a STOP condition. STOP is indicated by  
pulling SDA from low to high, while SCL is high.  
GENERAL CALL RESET  
The TMP421/22/23 support reset via the two-wire  
General Call address 00h (0000 0000b). The  
TMP421/22/23 acknowledge the General Call  
address and respond to the second byte. If the  
second byte is 06h (0000 0110b), the TMP421/22/23  
execute a software reset. This software reset restores  
the power-on reset state to all TMP421/22/23  
registers, and aborts any conversion in progress. The  
TMP421/22/23 take no action in response to other  
values in the second byte.  
SERIAL INTERFACE  
The TMP421/22/23 operate only as a slave device on  
either the two-wire bus or the SMBus. Connections to  
either bus are made via the open-drain I/O lines, SDA  
and SCL. The SDA and SCL pins feature integrated  
spike suppression filters and Schmitt triggers to  
minimize the effects of input spikes and bus noise.  
The TMP421/22/23 support the transmission protocol  
for fast (1kHz to 400kHz) and high-speed (1kHz to  
3.4MHz) modes. All data bytes are transmitted MSB  
first.  
IDENTIFICATION REGISTERS  
The TMP421/22/23 allow for the two-wire bus  
controller to query the device for manufacturer and  
device IDs to enable software identification of the  
device at the particular two-wire bus address. The  
manufacturer ID is obtained by reading from pointer  
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SERIAL BUS ADDRESS  
DXN connection should be left unconnected. The  
polarity of the transistor for external channel 2 (pins 3  
and 4) sets the least significant bit of the slave  
address. The polarity of the transistor for external  
channel 1 (pins 1 and 2) sets the next least  
significant bit of the slave address.  
To communicate with the TMP421/22/23, the master  
must first address slave devices via a slave address  
byte. The slave address byte consists of seven  
address bits, and a direction bit indicating the intent  
of executing a read or write operation.  
Table 9. TMP421 Slave Address Options  
Two-Wire Interface Slave Device Addresses  
TWO-WIRE SLAVE  
The TMP421 supports nine slave device addresses  
and the TMP422 supports four slave device  
addresses. The TMP423 has one of two factory-  
preset slave addresses.  
ADDRESS  
0011 100  
0011 101  
0011 110  
0011 111  
0101 010  
1001 100  
1001 101  
1001 110  
1001 111  
A1  
A0  
Float  
0
1
Float  
0
Float  
Float  
Float  
0
The slave device address for the TMP421 is set by  
the A1 and A0 pins according to Table 9.  
1
Float  
The slave device address for the TMP422 is set by  
the connections between the external transistors and  
the TMP422 according to Figure 15 and Table 10. If  
one of the channels is unused, the respective DXP  
connection should be connected to GND, and the  
0
0
1
1
1
0
1
Table 10. TMP422 Slave Address Options  
TWO-WIRE SLAVE ADDRESS  
1001 100  
DX1  
DX2  
DX3  
DX4  
DXP1  
DXP1  
DXN1  
DXN1  
DXN1  
DXN1  
DXP1  
DXP1  
DXP2  
DXN2  
DXP2  
DXN2  
DXN2  
DXP2  
DXN2  
DXP2  
1001 101  
1001 110  
1001 111  
SCL  
SDA  
V+  
DX1  
DX2  
DX3  
DX4  
V+  
SCL  
SDA  
GND  
DX1  
DX2  
DX3  
DX4  
V+  
DX1  
V+  
SCL  
SDA  
GND  
DX1  
DX2  
DX3  
DX4  
V+  
SCL  
SDA  
GND  
Q0  
Q2  
SCL  
SDA  
GND  
Q4  
DX2  
DX3  
DX4  
Q6  
Q3  
Q5  
Q7  
Q1  
Address = 1001100  
Address = 1001101  
Address = 1001110  
Address = 1001111  
Figure 15. TMP422 Connections for Device Address Setup  
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The TMP422 checks the polarity of the external  
transistor at power-on, or after software reset, by  
forcing current to pin 1 while connecting pin 2 to  
approximately 0.6V. If the voltage on pin 1 does not  
pull up to near the V+ of the TMP422, pin 1 functions  
as DXP for channel 1, and the second LSB of the  
slave address is '0'. If the voltage on pin 1 does pull  
up to near V+, the TMP422 forces current to pin 2  
while connecting pin 1 to 0.6V. If the voltage on pin 2  
does not pull up to near V+, the TMP422 uses pin 2  
for DXP of channel 1, and sets the second LSB of the  
slave address to '1'. If both pins are shorted to GND  
or if both pins are open, the TMP422 uses pin 1 as  
DXP and sets the address bit to '0'. This process is  
then repeated for channel 2 (pins 3 and 4).  
READ/WRITE OPERATIONS  
Accessing a particular register on the TMP421/22/23  
is accomplished by writing the appropriate value to  
the Pointer Register. The value for the Pointer  
Register is the first byte transferred after the slave  
address byte with the R/W bit low. Every write  
operation to the TMP421/22/23 requires a value for  
the Pointer Register (see Figure 17).  
When reading from the TMP421/22/23, the last value  
stored in the Pointer Register by a write operation is  
used to determine which register is read by a read  
operation. To change which register is read for a read  
operation, a new value must be written to the Pointer  
Register. This transaction is accomplished by issuing  
a slave address byte with the R/W bit low, followed  
by the Pointer Register byte; no additional data are  
required. The master can then generate a START  
condition and send the slave address byte with the  
R/W bit high to initiate the read command. See  
Figure 19 for details of this sequence. If repeated  
reads from the same register are desired, it is not  
necessary to continually send the Pointer Register  
bytes, because the TMP421/22/23 retain the Pointer  
Register value until it is changed by the next write  
operation. Note that register bytes are sent MSB first,  
followed by the LSB.  
If the TMP422 is to be used with transistors that are  
located on another IC (such as a CPU, DSP, or  
graphics processor), it is recommended to use pin 1  
or pin 3 as DXP to ensure correct address detection.  
If the other IC has a lower supply voltage or is not  
powered when the TMP422 tries to detect the slave  
address, a protection diode may turn on during the  
detection process and the TMP422 may incorrectly  
choose the DXP pin and corresponding slave  
address. Using pin 1 and/or pin 3 for transistors that  
are on other ICs ensures correct operation  
independent of supply sequencing or levels.  
Read operations should be terminated by issuing a  
Not-Acknowledge command at the end of the last  
byte to be read. For a single-byte operation, the  
master should leave the SDA line high during the  
Acknowledge time of the first byte that is read from  
the slave. For a two-byte read operation, the master  
must pull SDA low during the Acknowledge time of  
the first byte read, and should leave SDA high during  
the Acknowledge time of the second byte read from  
the slave.  
The TMP423 has a factory-preset slave address. The  
TMP423A slave address is 1001100b, and the  
TMP423B slave address is 1001101b. The  
configuration of the DXP and DXN channels are  
independent of the address. Unused DXP channels  
can be left open or tied to GND.  
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TIMING DIAGRAMS  
Data Transfer: The number of data bytes transferred  
between a START and a STOP condition is not  
limited and is determined by the master device. The  
receiver acknowledges data transfer.  
The TMP421/22/23 are two-wire and SMBus-  
compatible. Figure 16 to Figure 19 describe the  
timing for various operations on the TMP421/22/23.  
Parameters for Figure 16 are defined in Table 11.  
Bus definitions are:  
Acknowledge: Each receiving device, when  
addressed, is obliged to generate an Acknowledge  
bit. A device that acknowledges must pull down the  
SDA line during the Acknowledge clock pulse in such  
a way that the SDA line is stable low during the high  
period of the Acknowledge clock pulse. Setup and  
hold times must be taken into account. On a master  
receive, data transfer termination can be signaled by  
the master generating a Not-Acknowledge on the last  
byte that has been transmitted by the slave.  
Bus Idle: Both SDA and SCL lines remain high.  
Start Data Transfer: A change in the state of the  
SDA line, from high to low, while the SCL line is high,  
defines a START condition. Each data transfer  
initiates with a START condition. Denoted as S in  
Figure 16.  
Stop Data Transfer: A change in the state of the  
SDA line from low to high while the SCL line is high  
defines  
terminates with  
a
STOP condition. Each data transfer  
repeated START or STOP  
a
condition. Denoted as P in Figure 16.  
t(LOW)  
tR  
tF  
t(HDSTA)  
SCL  
t(SUSTO)  
t(HDSTA)  
t(HIGH)  
t(SUSTA)  
t(SUDAT)  
t(HDDAT)  
SDA  
t(BUF)  
P
S
S
P
Figure 16. Two-Wire Timing Diagram  
Table 11. Timing Characteristics for Figure 16  
FAST MODE  
HIGH-SPEED MODE  
PARAMETER  
MIN  
0.001  
600  
MAX  
MIN  
0.001  
160  
MAX  
UNIT  
SCL Operating Frequency  
f(SCL)  
t(BUF)  
0.4  
3.4  
MHz  
ns  
Bus Free Time Between STOP and START Condition  
Hold time after repeated START condition. After this period, the first clock  
is generated.  
t(HDSTA)  
100  
100  
ns  
Repeated START Condition Setup Time  
STOP Condition Setup Time  
Data Hold Time  
t(SUSTA)  
t(SUSTO)  
t(HDDAT)  
t(SUDAT)  
t(LOW)  
t(HIGH)  
tF  
100  
100  
0(1)  
100  
100  
0(2)  
10  
ns  
ns  
ns  
ns  
ns  
ns  
ns  
Data Setup Time  
100  
1300  
600  
SCL Clock LOW Period  
SCL Clock HIGH Period  
Clock/Data Fall Time  
160  
60  
300  
300  
160  
160  
Clock/Data Rise Time  
for SCL ≤ 100kHz  
tR  
ns  
tR  
1000  
(1) For cases with fall time of SCL less than 20ns and/or the rise or fall time of SDA less than 20ns, the hold time should be greater than  
20ns.  
(2) For cases with a fall time of SCL less than 10ns and/or the rise or fall time of SDA less than 10ns, the hold time should be greater than  
10ns.  
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1
1
9
1
9
SCL  
SDA  
¼
0
0
1
1
0
0(1) R/W  
P7 P6 P5 P4 P3  
P2 P1  
P0  
¼
Start By  
Master  
ACK By  
ACK By  
TMP421/22/23  
TMP421/22/23  
Frame 2 Pointer Register Byte  
Frame 1 Two-Wire Slave Address Byte  
1
9
SCL  
(Continued)  
SDA  
D7 D6 D5 D4 D3 D2 D1 D0  
(Continued)  
ACK By  
Stop By  
Master  
TMP421/22/23  
Frame 3 Data Byte 1  
(1) Slave address 1001100 shown.  
Figure 17. Two-Wire Timing Diagram for Write Word Format  
1
9
1
9
¼
¼
SCL  
SDA  
1
0
0
1
1
0
0(1)  
R/W  
P7  
P6  
P5  
P4  
P3  
P2  
P1  
P0  
Start By  
Master  
ACK By  
ACK By  
TMP421/22/23  
TMP421/22/23  
Frame 1 Two-Wire Slave Address Byte  
Frame 2 Pointer Register Byte  
1
9
1
9
SCL  
¼
¼
(Continued)  
SDA  
1
0
0(1)  
1
0
0
1
R/W  
D7  
D6  
D5  
D4 D3  
D2  
D1  
D0  
(Continued)  
Start By  
Master  
ACK By  
From  
TMP421/22/23  
NACK By  
Master(2)  
TMP421/22/23  
Frame 3 Two-Wire Slave Address Byte  
Frame 4 Data Byte 1 Read Register  
(1) Slave address 1001100 shown.  
(2) Master should leave SDA high to terminate a single-byte read operation.  
Figure 18. Two-Wire Timing Diagram for Single-Byte Read Format  
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1
9
1
9
¼
SCL  
0(1)  
R/W  
P7  
P6  
P5  
P4  
P3  
P2  
P1  
P0  
¼
SDA  
1
0
0
1
1
0
Start By  
Master  
ACK By  
ACK By  
TMP421/22/23  
TMP421/22/23  
Frame 1 Two-Wire Slave Address Byte  
Frame 2 Pointer Register Byte  
1
9
1
9
SCL  
¼
(Continued)  
SDA  
0(1)  
¼
1
0
1
0
0
1
R/W  
D7  
D6  
D5  
D4 D3  
D2  
D1  
D0  
(Continued)  
Start By  
Master  
ACK By  
From  
TMP421/22/23  
ACK By  
Master  
TMP421/22/23  
Frame 3 Two-Wire Slave Address Byte  
Frame 4 Data Byte 1 Read Register  
1
9
SCL  
(Continued)  
SDA  
D7 D6  
D5  
D4  
D3  
D2  
D1  
D0  
(Continued)  
From  
NACK By Stop By  
Master(2)  
Master  
TMP421/22/23  
Frame 5 Data Byte 2 Read Register  
(1) Slave address 1001100 shown.  
(2) Master should leave SDA high to terminate a two-byte read operation.  
Figure 19. Two-Wire Timing Diagram for Two-Byte Read Format  
HIGH-SPEED MODE  
to initiate data transfer operation. The bus  
a
continues to operate in Hs-mode until a STOP  
condition occurs on the bus. Upon receiving the  
STOP condition, the TMP421/22/23 switch the input  
and output filters back to fast mode operation.  
In order for the two-wire bus to operate at frequencies  
above 400kHz, the master device must issue a High-  
Speed mode (Hs-mode) master code (0000 1xxx) as  
the first byte after a START condition to switch the  
bus to high-speed operation. The TMP421/22/23 do  
not acknowledge this byte, but switch the input filters  
on SDA and SCL and the output filter on SDA to  
operate in Hs-mode, allowing transfers at up to  
3.4MHz. After the Hs-mode master code has been  
issued, the master transmits a two-wire slave address  
TIMEOUT FUNCTION  
The TMP421/22/23 reset the serial interface if either  
SCL or SDA are held low for 30ms (typical) between  
a START and STOP condition. If the TMP421/22/23  
are holding the bus low, the device releases the bus  
and waits for a START condition. To avoid activating  
the timeout function, it is necessary to maintain a  
communication speed of at least 1kHz for the SCL  
operating frequency.  
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SHUTDOWN MODE (SD)  
DX4 (TMP422), to minimize the effects of noise.  
However, a bypass capacitor placed differentially  
across the inputs of the remote temperature sensor is  
recommended to make the application more robust  
against unwanted coupled signals. The value of this  
capacitor should be between 100pF and 1nF. Some  
applications attain better overall accuracy with  
additional series resistance; however, this increased  
accuracy is application-specific. When series  
resistance is added, the total value should not be  
greater than 3kΩ. If filtering is needed, suggested  
component values are 100pF and 50Ω on each input;  
exact values are application-specific.  
The TMP421/22/23 Shutdown Mode allows the user  
to save maximum power by shutting down all device  
circuitry other than the serial interface, reducing  
current consumption to typically less than 3μA; see  
Figure 10, Shutdown Quiescent Current vs Supply  
Voltage. Shutdown Mode is enabled when the SD bit  
(bit 6) of Configuration Register 1 is high; the device  
shuts down once the current conversion is completed.  
When SD is low, the device maintains a continuous  
conversion state.  
SENSOR FAULT  
REMOTE SENSING  
The TMP421 can sense a fault at the DXP input  
resulting from incorrect diode connection. The  
TMP421/22/23 can all sense an open circuit. Short-  
circuit conditions return a value of –64°C. The  
detection circuitry consists of a voltage comparator  
that trips when the voltage at DXP exceeds  
(V+) – 0.6V (typical). The comparator output is  
continuously checked during a conversion. If a fault is  
detected, the OPEN bit (bit 0) in the temperature  
result register is set to '1' and the rest of the register  
bits should be ignored.  
The TMP421/22/23 are designed to be used with  
either discrete transistors or substrate transistors built  
into processor chips and ASICs. Either NPN or PNP  
transistors can be used, as long as the base-emitter  
junction is used as the remote temperature sense.  
NPN transistors must be diode-connected. PNP  
transistors can either be transistor- or diode-  
connected (see Figure 11, Figure 12, and Figure 13).  
Errors in remote temperature sensor readings are  
typically the consequence of the ideality factor and  
current excitation used by the TMP421/22/23 versus  
the manufacturer-specified operating current for a  
given transistor. Some manufacturers specify a high-  
level and low-level current for the temperature-  
sensing substrate transistors. The TMP421/22/23 use  
When not using the remote sensor with the TMP421,  
the DXP and DXN inputs must be connected together  
to prevent meaningless fault warnings. When not  
using a remote sensor with the TMP422, the DX pins  
should be connected (refer to Table 10) such that  
DXP connections are grounded and DXN connections  
are left open (unconnected). Unused TMP423 DXP  
pins can be left open or connected to GND.  
6μA for ILOW and 120μA for IHIGH  
.
The ideality factor (η) is a measured characteristic of  
a remote temperature sensor diode as compared to  
an ideal diode. The TMP421/22/23 allow for different  
η-factor values; see the N-Factor Correction Register  
section.  
UNDERVOLTAGE LOCKOUT  
The TMP421/22/23 sense when the power-supply  
voltage has reached a minimum voltage level for the  
ADC to function. The detection circuitry consists of a  
voltage comparator that enables the ADC after the  
power supply (V+) exceeds 2.45V (typical). The  
comparator output is continuously checked during a  
conversion. The TMP421/22/23 do not perform a  
temperature conversion if the power supply is not  
valid. The PVLD bit (bit 1, see Table 3) of the  
individual Local/Remote Temperature Register is set  
to '1' and the temperature result may be incorrect.  
The ideality factor for the TMP421/22/23 is trimmed  
to be 1.008. For transistors that have an ideality  
factor that does not match the TMP421/22/23,  
Equation 4 can be used to calculate the temperature  
error. Note that for the equation to be used correctly,  
actual temperature (°C) must be converted to kelvins  
(K).  
h - 1.008  
TERR  
=
´ (273.15 + T(°C))  
1.008  
(4)  
FILTERING  
Where:  
Remote junction temperature sensors are usually  
implemented in a noisy environment. Noise is most  
often created by fast digital signals, and it can corrupt  
measurements. The TMP421/22/23 have a built-in  
65kHz filter on the inputs of DXP and DXN  
(TMP421/TMP423), or on the inputs of DX1 through  
η = ideality factor of remote temperature sensor  
T(°C) = actual temperature  
TERR = error in TMP421/22/23 because η ≠ 1.008  
Degree delta is the same for °C and K  
Copyright © 2007–2012, Texas Instruments Incorporated  
Submit Documentation Feedback  
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TMP422  
TMP423  
SBOS398C –JULY 2007–REVISED MAY 2012  
www.ti.com  
For η = 1.004 and T(°C) = 100°C:  
power dissipated as a result of exciting the remote  
temperature sensor is negligible because of the small  
currents used. For a 5.5V supply and maximum  
conversion rate of eight conversions per second, the  
TMP421/22/23 dissipate 2.3mW (PDIQ = 5.5V ×  
415μA). A θJA of 100°C/W (for SOT23 package)  
causes the junction temperature to rise approximately  
+0.23°C above the ambient.  
1.004 * 1.008  
ǒ
Ǔ
+ ǒ  
Ǔ
TERR  
  273.15 ) 100°C  
1.008  
TERR + 1.48°C  
(5)  
If a discrete transistor is used as the remote  
temperature sensor with the TMP421/22/23, the best  
accuracy can be achieved by selecting the transistor  
according to the following criteria:  
LAYOUT CONSIDERATIONS  
Remote temperature sensing on the TMP421/22/23  
measures very small voltages using very low  
currents; therefore, noise at the IC inputs must be  
1. Base-emitter voltage > 0.25V at 6μA, at the  
highest sensed temperature.  
2. Base-emitter voltage < 0.95V at 120μA, at the  
minimized.  
Most  
applications  
using  
the  
lowest sensed temperature.  
TMP421/22/23 will have high digital content, with  
several clocks and logic level transitions creating a  
noisy environment. Layout should adhere to the  
following guidelines:  
3. Base resistance < 100Ω.  
4. Tight control of VBE characteristics indicated by  
small variations in hFE (that is, 50 to 150).  
1. Place the TMP421/22/23 as close to the remote  
junction sensor as possible.  
Based on these criteria, two recommended small-  
signal transistors are the 2N3904 (NPN) or 2N3906  
(PNP).  
2. Route the DXP and DXN traces next to each  
other and shield them from adjacent signals  
through the use of ground guard traces; see  
Figure 20. If a multilayer PCB is used, bury these  
traces between ground or V+ planes to shield  
MEASUREMENT ACCURACY AND THERMAL  
CONSIDERATIONS  
The temperature measurement accuracy of the  
TMP421/22/23 depends on the remote and/or local  
temperature sensor being at the same temperature  
as the system point being monitored. Clearly, if the  
temperature sensor is not in good thermal contact  
with the part of the system being monitored, then  
there will be a delay in the response of the sensor to  
a temperature change in the system. For remote  
temperature-sensing applications using a substrate  
transistor (or a small, SOT23 transistor) placed close  
to the device being monitored, this delay is usually  
not a concern.  
them from extrinsic noise sources.  
(0.127mm) PCB traces are recommended.  
5
mil  
3. Minimize additional thermocouple junctions  
caused by copper-to-solder connections. If these  
junctions are used, make the same number and  
approximate  
locations  
of  
copper-to-solder  
connections in both the DXP and DXN  
connections to cancel any thermocouple effects.  
4. Use a 0.1μF local bypass capacitor directly  
between the V+ and GND of the TMP421/22/23;  
see Figure 21. Minimize filter capacitance  
between DXP and DXN to 1000pF or less for  
optimum measurement performance. This  
capacitance includes any cable capacitance  
between the remote temperature sensor and the  
TMP421/22/23.  
The  
local  
temperature  
sensor  
inside  
the  
TMP421/22/23 monitors the ambient air around the  
device. The thermal time constant for the  
TMP421/22/23 is approximately two seconds. This  
constant implies that if the ambient air changes  
quickly by 100°C, it would take the TMP421/22/23  
about 10 seconds (that is, five thermal time  
constants) to settle to within 1°C of the final value. In  
most applications, the TMP421/22/23 package is in  
electrical, and therefore thermal, contact with the  
printed circuit board (PCB), as well as subjected to  
forced airflow. The accuracy of the measured  
temperature directly depends on how accurately the  
PCB and forced airflow temperatures represent the  
temperature that the TMP421/22/23 is measuring.  
Additionally, the internal power dissipation of the  
TMP421/22/23 can cause the temperature to rise  
above the ambient or PCB temperature. The internal  
5. If the connection between the remote  
temperature sensor and the TMP421/22/23 is  
less than 8 in (20.32 cm) long, use a twisted-wire  
pair connection. Beyond 8 in, use a twisted,  
shielded pair with the shield grounded as close to  
the TMP421/22/23 as possible. Leave the remote  
sensor connection end of the shield wire open to  
avoid ground loops and 60Hz pickup.  
6. Thoroughly clean and remove all flux residue in  
and around the pins of the TMP421/22/23 to  
avoid temperature offset readings as a result of  
leakage paths between DXP or DXN and GND,  
or between DXP or DXN and V+.  
24  
Submit Documentation Feedback  
Copyright © 2007–2012, Texas Instruments Incorporated  
Product Folder Link(s): TMP421 TMP422 TMP423  
 
 
TMP421  
TMP422  
TMP423  
www.ti.com  
SBOS398C –JULY 2007–REVISED MAY 2012  
V+  
DXP  
DXN  
GND  
Ground or V+ layer  
on bottom and/or  
top, if possible.  
NOTE: Use minimum 5 mil (0.127mm) traces with 5 mil spacing.  
Figure 20. Suggested PCB Layer Cross-Section  
0.1mF Capacitor  
0.1mF Capacitor  
GND  
GND  
PCB Via  
PCB Via  
V+  
V+  
DXP  
DXN  
A1  
1
2
3
4
8
7
6
5
DX1  
DX2  
DX3  
DX4  
1
2
3
4
8
7
6
5
A0  
TMP421  
TMP422  
0.1mF Capacitor  
0.1mF Capacitor  
GND  
GND  
PCB Via  
PCB Via  
DXP  
DXN  
A1  
1
8
7
6
5
V+  
V+  
DXP1  
DXP2  
DXP3  
DXN  
1
2
3
4
8
7
6
5
2
3
4
A0  
TMP421C  
TMP423  
Figure 21. Suggested Bypass Capacitor Placement and Trace Shielding  
Copyright © 2007–2012, Texas Instruments Incorporated  
Submit Documentation Feedback  
25  
Product Folder Link(s): TMP421 TMP422 TMP423  
 
 
TMP421  
TMP422  
TMP423  
SBOS398C –JULY 2007–REVISED MAY 2012  
www.ti.com  
REVISION HISTORY  
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.  
Changes from Revision B (March 2008) to Revision C  
Page  
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Removed package name from title ....................................................................................................................................... 1  
Added new DSBGA package to feature bullet ...................................................................................................................... 1  
Added TMP421C device to Description section ................................................................................................................... 1  
Added TMP421C device with DSBGA package to Package Information table .................................................................... 2  
Added new Electrical Characteristics table for TMP421C .................................................................................................... 4  
Changed V+ pin voltage range in all Pin Assignment tables from 2.7V to 2.55V ................................................................ 5  
Added DSBGA package to TMP421 Pin Configuration section ........................................................................................... 5  
Changed supply voltage minimum range for pin 8 from 2.55V to 2.7V in TMP422 Pin Assignments table ........................ 5  
Changed supply voltage minimum range for pin 8 from 2.55V to 2.7V in TMP423 Pin Assignments table ........................ 6  
Changed label from VS to V+ and value from 2.7V to 2.55V in Figure 4 ............................................................................. 7  
Changed label from VS to V+ and value from 2.7V to 2.55V in Figure 5 ............................................................................. 8  
Changed label from VS to V+ and value from 2.7V to 2.55V in Figure 8 ............................................................................. 8  
Added new DSBGA package text to first paragraph of Application Information section ...................................................... 9  
Changed text in first paragraph of Application Information section ...................................................................................... 9  
Changed text in first paragraph of Application Information section to clarify temperature measurement channels ............ 9  
Changed text in last paragraph of Application Information section ...................................................................................... 9  
Changed minimum temperature value for bit 2 = 0 from –55°C to –40°C in Table 5 ......................................................... 14  
Changed header row for Table 6 ........................................................................................................................................ 15  
Changed VS to V+ in Table 7 .............................................................................................................................................. 16  
Added "(for SOT23 package)" to end of Measurement Accuracy and Thermal Considerations section ........................... 24  
Changed VDD to V+ in bullet 2 of Layout Considerations section ....................................................................................... 24  
Added TMP421C to Figure 21 ............................................................................................................................................ 25  
26  
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Copyright © 2007–2012, Texas Instruments Incorporated  
Product Folder Link(s): TMP421 TMP422 TMP423  
PACKAGE OPTION ADDENDUM  
www.ti.com  
15-May-2012  
PACKAGING INFORMATION  
Status (1)  
Eco Plan (2)  
MSL Peak Temp (3)  
Samples  
Orderable Device  
Package Type Package  
Drawing  
Pins  
Package Qty  
Lead/  
Ball Finish  
(Requires Login)  
TMP421AIDCNR  
TMP421AIDCNRG4  
TMP421AIDCNT  
TMP421AIDCNTG4  
TMP421YZDR  
ACTIVE  
ACTIVE  
ACTIVE  
ACTIVE  
ACTIVE  
ACTIVE  
ACTIVE  
ACTIVE  
ACTIVE  
ACTIVE  
ACTIVE  
ACTIVE  
ACTIVE  
ACTIVE  
ACTIVE  
ACTIVE  
ACTIVE  
SOT-23  
SOT-23  
SOT-23  
SOT-23  
DSBGA  
DSBGA  
SOT-23  
SOT-23  
SOT-23  
SOT-23  
SOT-23  
SOT-23  
SOT-23  
SOT-23  
SOT-23  
SOT-23  
SOT-23  
DCN  
DCN  
DCN  
DCN  
YZD  
YZD  
DCN  
DCN  
DCN  
DCN  
DCN  
DCN  
DCN  
DCN  
DCN  
DCN  
DCN  
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
3000  
3000  
250  
Green (RoHS  
& no Sb/Br)  
CU NIPDAU Level-2-260C-1 YEAR  
Green (RoHS  
& no Sb/Br)  
CU NIPDAU Level-2-260C-1 YEAR  
CU NIPDAU Level-2-260C-1 YEAR  
CU NIPDAU Level-2-260C-1 YEAR  
SNAGCU Level-1-260C-UNLIM  
SNAGCU Level-1-260C-UNLIM  
CU NIPDAU Level-2-260C-1 YEAR  
CU NIPDAU Level-2-260C-1 YEAR  
CU NIPDAU Level-2-260C-1 YEAR  
CU NIPDAU Level-2-260C-1 YEAR  
CU NIPDAU Level-2-260C-1 YEAR  
CU NIPDAU Level-2-260C-1 YEAR  
CU NIPDAU Level-2-260C-1 YEAR  
CU NIPDAU Level-2-260C-1 YEAR  
CU NIPDAU Level-2-260C-1 YEAR  
CU NIPDAU Level-2-260C-1 YEAR  
CU NIPDAU Level-2-260C-1 YEAR  
Green (RoHS  
& no Sb/Br)  
250  
Green (RoHS  
& no Sb/Br)  
3000  
250  
Green (RoHS  
& no Sb/Br)  
TMP421YZDT  
Green (RoHS  
& no Sb/Br)  
TMP422AIDCNR  
TMP422AIDCNRG4  
TMP422AIDCNT  
TMP422AIDCNTG4  
TMP423AIDCNR  
TMP423AIDCNRG4  
TMP423AIDCNT  
TMP423AIDCNTG4  
TMP423BIDCNR  
TMP423BIDCNRG4  
TMP423BIDCNT  
3000  
3000  
250  
Green (RoHS  
& no Sb/Br)  
Green (RoHS  
& no Sb/Br)  
Green (RoHS  
& no Sb/Br)  
250  
Green (RoHS  
& no Sb/Br)  
3000  
3000  
250  
Green (RoHS  
& no Sb/Br)  
Green (RoHS  
& no Sb/Br)  
Green (RoHS  
& no Sb/Br)  
250  
Green (RoHS  
& no Sb/Br)  
3000  
3000  
250  
Green (RoHS  
& no Sb/Br)  
Green (RoHS  
& no Sb/Br)  
Green (RoHS  
& no Sb/Br)  
Addendum-Page 1  
PACKAGE OPTION ADDENDUM  
www.ti.com  
15-May-2012  
Status (1)  
Eco Plan (2)  
MSL Peak Temp (3)  
Samples  
Orderable Device  
Package Type Package  
Drawing  
Pins  
Package Qty  
Lead/  
Ball Finish  
(Requires Login)  
TMP423BIDCNTG4  
ACTIVE  
SOT-23  
DCN  
8
250  
Green (RoHS  
& no Sb/Br)  
CU NIPDAU Level-2-260C-1 YEAR  
(1) The marketing status values are defined as follows:  
ACTIVE: Product device recommended for new designs.  
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.  
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.  
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.  
OBSOLETE: TI has discontinued the production of the device.  
(2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability  
information and additional product content details.  
TBD: The Pb-Free/Green conversion plan has not been defined.  
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that  
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.  
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between  
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.  
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight  
in homogeneous material)  
(3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.  
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information  
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and  
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.  
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.  
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.  
OTHER QUALIFIED VERSIONS OF TMP422 :  
Enhanced Product: TMP422-EP  
•
NOTE: Qualified Version Definitions:  
Enhanced Product - Supports Defense, Aerospace and Medical Applications  
•
Addendum-Page 2  
PACKAGE MATERIALS INFORMATION  
www.ti.com  
25-May-2012  
TAPE AND REEL INFORMATION  
*All dimensions are nominal  
Device  
Package Package Pins  
Type Drawing  
SPQ  
Reel  
Reel  
A0  
B0  
K0  
P1  
W
Pin1  
Diameter Width (mm) (mm) (mm) (mm) (mm) Quadrant  
(mm) W1 (mm)  
TMP421AIDCNR  
TMP421AIDCNT  
TMP421YZDR  
SOT-23  
SOT-23  
DSBGA  
DSBGA  
SOT-23  
SOT-23  
SOT-23  
SOT-23  
SOT-23  
SOT-23  
DCN  
DCN  
YZD  
YZD  
DCN  
DCN  
DCN  
DCN  
DCN  
DCN  
8
8
8
8
8
8
8
8
8
8
3000  
250  
179.0  
179.0  
180.0  
180.0  
179.0  
179.0  
179.0  
179.0  
179.0  
179.0  
8.4  
8.4  
8.4  
8.4  
8.4  
8.4  
8.4  
8.4  
8.4  
8.4  
3.2  
3.2  
1.1  
1.1  
3.2  
3.2  
3.2  
3.2  
3.2  
3.2  
3.2  
3.2  
2.29  
2.29  
3.2  
3.2  
3.2  
3.2  
3.2  
3.2  
1.4  
1.4  
0.69  
0.69  
1.4  
1.4  
1.4  
1.4  
1.4  
1.4  
4.0  
4.0  
4.0  
4.0  
4.0  
4.0  
4.0  
4.0  
4.0  
4.0  
8.0  
8.0  
8.0  
8.0  
8.0  
8.0  
8.0  
8.0  
8.0  
8.0  
Q3  
Q3  
Q1  
Q1  
Q3  
Q3  
Q3  
Q3  
Q3  
Q3  
3000  
250  
TMP421YZDT  
TMP422AIDCNR  
TMP422AIDCNT  
TMP423AIDCNR  
TMP423AIDCNT  
TMP423BIDCNR  
TMP423BIDCNT  
3000  
250  
3000  
250  
3000  
250  
Pack Materials-Page 1  
PACKAGE MATERIALS INFORMATION  
www.ti.com  
25-May-2012  
*All dimensions are nominal  
Device  
Package Type Package Drawing Pins  
SPQ  
Length (mm) Width (mm) Height (mm)  
TMP421AIDCNR  
TMP421AIDCNT  
TMP421YZDR  
SOT-23  
SOT-23  
DSBGA  
DSBGA  
SOT-23  
SOT-23  
SOT-23  
SOT-23  
SOT-23  
SOT-23  
DCN  
DCN  
YZD  
YZD  
DCN  
DCN  
DCN  
DCN  
DCN  
DCN  
8
8
8
8
8
8
8
8
8
8
3000  
250  
195.0  
195.0  
210.0  
210.0  
195.0  
195.0  
195.0  
195.0  
195.0  
195.0  
200.0  
200.0  
185.0  
185.0  
200.0  
200.0  
200.0  
200.0  
200.0  
200.0  
45.0  
45.0  
35.0  
35.0  
45.0  
45.0  
45.0  
45.0  
45.0  
45.0  
3000  
250  
TMP421YZDT  
TMP422AIDCNR  
TMP422AIDCNT  
TMP423AIDCNR  
TMP423AIDCNT  
TMP423BIDCNR  
TMP423BIDCNT  
3000  
250  
3000  
250  
3000  
250  
Pack Materials-Page 2  
D: Max = 2.122 mm, Min =2.062 mm  
E: Max = 0.932 mm, Min =0.872 mm  
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