MAX6693UP9A [MAXIM]
7-Channel Precision Temperature Monitor with Beta Compensation; 7通道，高精度温度监测器beta补偿
| 型号： | MAX6693UP9A |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 7-Channel Precision Temperature Monitor with Beta Compensation |
| 文件： | 总19页 (文件大小：168K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-4096; Rev 0; 5/08
7-Channel Precision Temperature Monitor
with Beta Compensation
MAX693
General Description
Features
The MAX6693 precision multichannel temperature sen-
sor monitors its own temperature and the temperatures
of up to six external diode-connected transistors. All
temperature channels have programmable alert thresh-
olds. Channels 1, 4, 5, and 6 also have programmable
overtemperature thresholds. When the measured tem-
perature of a channel exceeds the respective thresh-
old, a status bit is set in one of the status registers. Two
open-drain outputs, OVERT and ALERT, assert corre-
sponding to these bits in the status register.
♦ Six Thermal-Diode Inputs
♦ Beta Compensation (Channel 1)
♦ Local Temperature Sensor
♦ 1.5°C Remote Temperature Accuracy (+60°C to
+100°C)
♦ Temperature Monitoring Begins at POR for Fail-
Safe System Protection
♦ ALERT and OVERT Outputs for Interrupts,
Throttling, and Shutdown
The 2-wire serial interface supports the standard system
management bus (SMBus™) protocols: write byte, read
byte, send byte, and receive byte for reading the tem-
perature data and programming the alarm thresholds.
♦ STBY Input for Hardware Standby Mode
♦ Small, 20-Pin TSSOP Package
♦ 2-Wire SMBus Interface
The MAX6693 is specified for an operating temperature
range of -40°C to +125°C and is available in a 20-pin
TSSOP package.
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
Applications
Desktop Computers
Notebook Computers
Workstations
MAX6693UP9A+
-40°C to +125°C 20 TSSOP
+Denotes a lead-free package.
Note: Slave address is 1001 101.
Servers
SMBus is a trademark of Intel Corp.
Pin Configuration appears at end of data sheet.
Typical Application Circuit
+3.3V
CPU
4.7kΩ
EACH
1
2
3
4
5
6
7
8
20
19
18
17
16
15
14
13
DXP1
DXN1
DXP2
DXN2
DXP3
DXN3
DXP4
DXN4
GND
SMBCLK
SMBDATA
ALERT
100pF
100pF
100pF
100pF
100pF
MAX6693
CLK
DATA
INTERRUPT
TO μP
V
CC
0.1μF
OVERT
TO SYSTEM
SHUTDOWN
N.C.
STBY
GPU
9
12
11
DXP5
DXN5
DXP6
DXN6
100pF
10
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
7-Channel Precision Temperature Monitor
with Beta Compensation
ABSOLUTE MAXIMUM RATINGS
Junction-to-Case Thermal Resistance (θ ) (Note 1)
20-Pin TSSOP...............................................................20°C/W
V
, SMBCLK, SMBDATA, ALERT, OVERT,
STBY to GND ....................................................-0.3V to +6.0V
DXP_ to GND..............................................-0.3V to (V + 0.3V)
JC
CC
Junction-to-Ambient Thermal Resistance (θ ) (Note 1)
JA
CC
20-Pin TSSOP............................................................73.8°C/W
ESD Protection (all pins, Human Body Model) .................... 2kV
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
DXN_ to GND ........................................................-0.3V to +0.8V
SMBDATA, ALERT, OVERT Current....................-1mA to +50mA
DXN_ Current...................................................................... 1mA
Continuous Power Dissipation (T = +70°C)
A
20-Pin TSSOP
(derate 13.6mW/°C above +70°C).............................1084mW
MAX693
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
= +3.0V to +3.6V, V
= V , T = -40°C to +125°C, unless otherwise noted. Typical values are at V
= +3.3V and T =
CC A
CC
STBY
CC
A
+25°C.) (Note 2)
PARAMETER
Supply Voltage
SYMBOL
CONDITIONS
MIN
TYP
MAX
3.6
UNITS
V
3.0
V
CC
SS
Software Standby Supply Current
Operating Current
I
SMBus static
3
500
11
8
10
µA
µA
I
During conversion (Note 3)
Channel 1 only
2000
CC
Temperature Resolution
Bits
°C
Other diode channels
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
A
= T = +60°C to +100°C
-1.5
-2.375
-2
+1.5
+2.375
+2
RJ
3 σ Temperature Accuracy
(Remote Channel 1)
V
= 3.3V,
CC
ß = 0.5
= T = 0°C to +125°C
RJ
= T = +60°C to +100°C
RJ
3 σ Temperature Accuracy
(Remote Channels 2–6)
V
V
= 3.3V
°C
CC
= T = 0°C to +125°C
RJ
-2.5
-2
+2.5
+2
= +60°C to +100°C
= 0°C to +125°C
3 σ Temperature Accuracy
(Local)
= 3.3V
= 3.3V,
°C
CC
-2.5
-3
+2.5
+3
= T = +60°C to +100°C
RJ
6 σ Temperature Accuracy
(Remote Channel 1)
V
CC
°C
ß = 0.5
= T = 0°C to +125°C
-4
+4
RJ
= T = +60°C to +100°C
-3
+3
RJ
6 σ Temperature Accuracy
(Remote Channels 2–6)
V
V
= 3.3V
= 3.3V
°C
CC
CC
= T = 0°C to +125°C
RJ
-3.5
-2.5
-3
+3.5
+2.5
+3
= +60°C to +100°C
= 0°C to +125°C
6 σ Temperature Accuracy
(Local)
°C
Supply Sensitivity of Temperature
Accuracy
0.2
250
125
oC/V
ms
ms
Remote Channel 1 Conversion
Time
t
190
95
312
156
CONV1
Remote Channels 2–6
Conversion Time
t
CONV_
2
_______________________________________________________________________________________
7-Channel Precision Temperature Monitor
with Beta Compensation
MAX693
ELECTRICAL CHARACTERISTICS (continued)
(V
= +3.0V to +3.6V, V
= V , T = -40°C to +125°C, unless otherwise noted. Typical values are at V
= +3.3V and T =
CC A
CC
STBY
CC
A
+25°C.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
High level, channel 1
MIN
TYP
500
20
MAX
UNITS
Low level, channel 1
Remote-Diode Source Current
I
µA
RJ
High level, channels 2–6
Low level, channels 2–6
80
8
100
10
120
12
Undervoltage-Lockout Threshold
Undervoltage-Lockout Hysteresis
Power-On Reset (POR) Threshold
POR Threshold Hysteresis
ALERT, OVERT
UVLO
Falling edge of V disables ADC
2.30
2.80
90
2.95
V
CC
mV
V
V
falling edge
1.20
2
2.25
CC
90
mV
I
I
= 1mA
= 6mA
0.3
0.5
1
SINK
SINK
Output Low Voltage
V
V
OL
Output Leakage Current
µA
SMBus INTERFACE (SMBCLK, SMBDATA), STBY
Logic-Input Low Voltage
Logic-Input High Voltage
Input Leakage Current
Output Low Voltage
V
0.8
V
V
IL
V
V
= 3.0V
2.2
-1
IH
CC
+1
µA
V
V
I
= 6mA
0.3
OL
SINK
Input Capacitance
C
5
pF
IN
SMBus-COMPATIBLE TIMING (Figures 3 and 4) (Note 4)
Serial-Clock Frequency
f
(Note 5)
400
kHz
µs
SMBCLK
f
f
f
f
= 100kHz
= 400kHz
= 100kHz
= 400kHz
4.7
1.6
4.7
0.6
SMBCLK
SMBCLK
SMBCLK
SMBCLK
Bus Free Time Between STOP
and START Condition
t
BUF
START Condition Setup Time
µs
90% of SMBCLK to 90% of SMBDATA,
= 100kHz
0.6
f
SMBCLK
Repeat START Condition Setup
Time
t
µs
µs
µs
SU:STA
HD:STA
SU:STO
90% of SMBCLK to 90% of SMBDATA,
= 400kHz
0.6
0.6
4
f
SMBCLK
START Condition Hold Time
STOP Condition Setup Time
t
t
10% of SMBDATA to 90% of SMBCLK
90% of SMBCLK to 90% of SMBDATA,
f
= 100kHz
SMBCLK
90% of SMBCLK to 90% of SMBDATA,
= 400kHz
0.6
f
SMBCLK
_______________________________________________________________________________________
3
7-Channel Precision Temperature Monitor
with Beta Compensation
ELECTRICAL CHARACTERISTICS (continued)
(V
= +3.0V to +3.6V, V
= V , T = -40°C to +125°C, unless otherwise noted. Typical values are at V
= +3.3V and T =
CC A
CC
STBY
CC
A
+25°C.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
1.3
TYP
MAX
UNITS
10% to 10%, f
10% to 10%, f
90% to 90%
= 100kHz
SMBCLK
SMBCLK
Clock-Low Period
Clock-High Period
Data Hold Time
t
µs
µs
ns
LOW
= 400kHz
1.3
t
0.6
HIGH
MAX693
f
f
f
f
f
f
= 100kHz
300
SMBCLK
SMBCLK
SMBCLK
SMBCLK
SMBCLK
SMBCLK
t
HD:DAT
= 400kHz (Note 6)
= 100kHz
900
250
100
Data Setup Time
t
ns
µs
ns
SU:DAT
= 400kHz
= 100kHz
1
Receive SMBCLK/SMBDATA
Rise Time
t
R
= 400kHz
0.3
Receive SMBCLK/SMBDATA Fall
Time
t
300
F
Pulse Width of Spike Suppressed
SMBus Timeout
t
0
50
45
ns
SP
t
SMBDATA low period for interface reset
25
37
ms
TIMEOUT
Note 2: All parameters are tested at T = +85°C. Specifications over temperature are guaranteed by design.
A
Note 3: Beta = 0.5 for channel 1 remote transistor.
Note 4: Timing specifications are guaranteed by design.
Note 5: The serial interface resets when SMBCLK is low for more than t
.
TIMEOUT
Note 6: A transition must internally provide at least a hold time to bridge the undefined region (300ns max) of SMBCLK’s falling edge.
4
_______________________________________________________________________________________
7-Channel Precision Temperature Monitor
with Beta Compensation
MAX693
Typical Operating Characteristics
(V
= 3.3V, V
= V , T = +25°C, unless otherwise noted.)
STBY CC A
CC
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
SOFTWARE STANDBY SUPPLY CURRENT
vs. SUPPLY VOLTAGE
580
560
540
520
500
480
460
440
420
400
3.8
LOW BETA DIODE CONNECTED TO
CHANNEL 1 WITH RESISTANCE
CANCELLATION AND LOW BETA
3.7
3.6
3.5
3.4
3.3
3.2
3.1
3.0
3.0
3.2
3.4
3.6
3.0
3.1
3.2
3.3
3.4
3.5
3.6
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
REMOTE-DIODE TEMPERATURE ERROR
vs. REMOTE-DIODE TEMPERATURE
LOCAL TEMPERATURE ERROR
vs. DIE TEMPERATURE
REMOTE-DIODE TEMPERATURE ERROR
vs. POWER-SUPPLY NOISE FREQUENCY
5
4
3
2
1
0
4
3
5
4
100mV
P-P
3
2
2
CHANNEL 2
CHANNEL 2
1
1
0
0
-1
-2
-3
-4
-5
-1
-2
-3
-4
-5
-1
-2
-3
CHANNEL 1
CHANNEL 1
0
25
50
75
100
125
0
25
50
75
100
125
0.001
0.010
0.100
1.000
10.000
REMOTE-DIODE TEMPERATURE (°C)
DIE TEMPERATURE (°C)
FREQUENCY (MHz)
LOCAL TEMPERATURE ERROR
vs. POWER-SUPPLY NOISE FREQUENCY
CH 2 REMOTE-DIODE TEMPERATURE ERROR
vs. COMMON-MODE NOISE FREQUENCY
5
4
4
100mV
P-P
100mV
P-P
3
2
1
0
3
2
1
0
-1
-1
-2
-3
-4
-5
-2
-3
-4
-5
0.001
0.010
0.100
1.000
10.000
0.1
1.0
10.0
FREQUENCY (MHz)
FREQUENCY (MHz)
_______________________________________________________________________________________
5
7-Channel Precision Temperature Monitor
with Beta Compensation
Typical Operating Characteristics (continued)
(V
= 3.3V, V
= V , T = +25°C, unless otherwise noted.)
STBY CC A
CC
CH 1 REMOTE-DIODE TEMPERATURE
ERROR vs. CAPACITANCE
CH 2 REMOTE-DIODE TEMPERATURE
ERROR vs. CAPACITANCE
5
4
3
2
1
0
5
4
3
2
MAX693
1
0
-1
-2
-3
-4
-5
-1
-2
-3
-4
-5
1
10
100
1
10
100
CAPACITANCE (nF)
CAPACITANCE (nF)
Pin Description
PIN
1
NAME
DXP1
DXN1
DXP2
FUNCTION
Combined Current Source and A/D Positive Input for Channel 1 Remote Transistor. Connect to the
emitter of a low-beta transistor. Leave unconnected or connect to V if no remote transistor is used.
CC
Place a 100pF capacitor between DXP1 and DXN1 for noise filtering.
2
Base Input for Channel 1 Remote Diode. Connect to the base of a PNP temperature-sensing transistor.
Combined Current Source and A/D Positive Input for Channel 2 Remote Diode. Connect to the anode
of a remote-diode-connected temperature-sensing transistor. Leave unconnected or connect to V
CC
3
if no remote diode is used. Place a 100pF capacitor between DXP2 and DXN2 for noise filtering.
Cathode Input for Channel 2 Remote Diode. Connect the cathode of the channel 2 remote-diode-
connected transistor to DXN2.
4
5
6
7
8
DXN2
DXP3
DXN3
DXP4
DXN4
Combined Current Source and A/D Positive Input for Channel 3 Remote Diode. Connect to the anode
of a remote-diode-connected temperature-sensing transistor. Leave unconnected or connect to V
CC
if no remote diode is used. Place a 100pF capacitor between DXP3 and DXN3 for noise filtering.
Cathode Input for Channel 3 Remote Diode. Connect the cathode of the channel 3 remote-diode-
connected transistor to DXN3.
Combined Current Source and A/D Positive Input for Channel 4 Remote Diode. Connect to the anode
of a remote-diode-connected temperature-sensing transistor. Leave unconnected or connect to V
CC
if no remote diode is used. Place a 100pF capacitor between DXP4 and DXN4 for noise filtering.
Cathode Input for Channel 4 Remote Diode. Connect the cathode of the channel 4 remote-diode-
connected transistor to DXN4.
6
_______________________________________________________________________________________
7-Channel Precision Temperature Monitor
with Beta Compensation
MAX693
Pin Description (continued)
PIN
NAME
FUNCTION
Combined Current Source and A/D Positive Input for Channel 5 Remote Diode. Connect to the anode
of a remote-diode-connected temperature-sensing transistor. Leave unconnected or connect to V
CC
9
DXP5
if no remote diode is used. Place a 100pF capacitor between DXP5 and DXN5 for noise filtering.
Cathode Input for Channel 5 Remote Diode. Connect the cathode of the channel 5 remote-diode-
connected transistor to DXN5.
10
11
DXN5
DXN6
Cathode Input for Channel 6 Remote Diode. Connect the cathode of the channel 6 remote-diode-
connected transistor to DXN6.
Combined Current Source and A/D Positive Input for Channel 6 Remote Diode. Connect to the anode
of a remote-diode-connected temperature-sensing transistor. Leave unconnected or connect to V
CC
12
DXP6
if no remote diode is used. Place a 100pF capacitor between DXP6 and DXN6 for noise filtering.
Active-Low Standby Input. Drive ST BY logic-low to place the MAX6693 in standby mode, or logic-high
for operate mode. Temperature and threshold data are retained in standby mode.
13
14
15
16
17
STBY
N.C.
No Connection. Must be connected to ground.
Overtemperature Active-Low, Open-Drain Output. OVERT asserts low when the temperature of
channels 1, 4, 5, and 6 exceeds the programmed threshold limit.
OVERT
V
Supply Voltage Input. Bypass to GND with a 0.1µF capacitor.
CC
SMBus Alert (Interrupt), Active-Low, Open-Drain Output. ALERT asserts low when the temperature of
any channel exceeds the programmed ALERT threshold.
ALERT
18
19
20
SMBDATA SMBus Serial Data Input/Output. Connect to a pullup resistor.
SMBCLK
GND
SMBus Serial Clock Input. Connect to a pullup resistor.
Ground
Low-Power Standby Mode
Enter software standby mode by setting the STOP bit to
1 in the configuration 1 register. Enter hardware standby
by pulling STBY low. Software standby mode disables
the ADC and reduces the supply current to approxi-
mately 3µA. Hardware standby mode halts the ADC
clock, but the supply current is approximately 350µA.
During either software or hardware standby, data is
retained in memory. During hardware standby, the
SMBus interface is inactive. During software standby, the
SMBus interface is active and listening for commands.
The timeout is enabled if a start condition is recognized
on SMBus. Activity on the SMBus causes the supply cur-
rent to increase. If a standby command is received while
a conversion is in progress, the conversion cycle is inter-
rupted, and the temperature registers are not updated.
The previous data is not changed and remains available.
Detailed Description
The MAX6693 is a precision multichannel temperature
monitor that features one local and six remote tempera-
ture-sensing channels with a programmable alert
threshold for each temperature channel and a program-
mable overtemperature threshold for channels 1, 4, 5,
and 6 (see Figure 1). Communication with the MAX6693
is achieved through the SMBus serial interface and a
dedicated alert pin. The alarm outputs, OVERT and
ALERT, assert if the software-programmed temperature
thresholds are exceeded. ALERT typically serves as an
interrupt, while OVERT can be connected to a fan, sys-
tem shutdown, or other thermal-management circuitry.
ADC Conversion Sequence
In the default conversion mode, the MAX6693 starts the
conversion sequence by measuring the temperature on
channel 1, followed by 2, 3, local channel, 4, 5, and 6.
The conversion result for each active channel is stored
in the corresponding temperature data register.
_______________________________________________________________________________________
7
7-Channel Precision Temperature Monitor
with Beta Compensation
V
CC
DXP
MAX6693
DXN
DXP2
MAX693
OVERT
ALERT
ALARM
ALU
DXN2
DXP3
CURRENT
SOURCES,
BETA
COMPEN-
SATION
AND MUX
DXN3
DXP4
INPUT
BUFFER
REGISTER BANK
COMMAND BYTE
ADC
REMOTE TEMPERATURES
LOCAL TEMPERATURES
ALERT THRESHOLD
DXN4
DXP5
REF
OVERT THRESHOLD
DXN5
DXP6
ALERT RESPONSE ADDRESS
SMBus
INTERFACE
DXN6
STBY
SMBCLK
SMBDATA
Figure 1. Internal Block Diagram
Operating-Current Calculation
The MAX6693 operates at different operating-current
levels depending on how many external channels are in
SMBus Digital Interface
From a software perspective, the MAX6693 appears as
a series of 8-bit registers that contain temperature mea-
surement data, alarm threshold values, and control bits.
A standard SMBus-compatible, 2-wire serial interface is
used to read temperature data and write control bits
and alarm threshold data. The same SMBus slave
address also provides access to all functions.
use. Assume that I
is the operating current when
CC1
the MAX6693 is converting the remote channel 1 and
is the operating current when the MAX6693 is con-
I
CC2
verting the other channels. For the MAX6693 with
remote channel 1 and n other remote channels con-
nected, the operating current is:
I
= (2 x I
+ I
+ n x I
)/(n + 3)
CC
CC1
CC2
CC2
8
_______________________________________________________________________________________
7-Channel Precision Temperature Monitor
with Beta Compensation
MAX693
WRITE BYTE FORMAT
S
ADDRESS
WR
ACK
COMMAND
ACK
DATA
ACK
P
7 BITS
8 BITS
8 BITS
1
SLAVE ADDRESS: EQUIVA-
LENT TO CHIP-SELECT LINE OF
A 3-WIRE INTERFACE
DATA BYTE: DATA GOES INTO THE REGISTER
SET BY THE COMMAND BYTE (TO SET
THRESHOLDS, CONFIGURATION MASKS, AND
SAMPLING RATE)
READ BYTE FORMAT
S
ADDRESS
WR
ACK
COMMAND
ACK
S
ADDRESS
7 BITS
RD
ACK
ACK
DATA
///
P
7 BITS
8 BITS
8 BITS
SLAVE ADDRESS: EQUIVA-
LENT TO CHIP SELECT LINE
COMMAND BYTE: SELECTS
WHICH REGISTER YOU ARE
REDING FROM
SLAVE ADDRESS: REPEATED
DUE TO CHANGE IN DATA-
FLOW DIRECTION
DATA BYTE: READS FROM
THE REGISTER SET BY THE
COMMAND BYTE
SEND BYTE FORMAT
S
RECEIVE BYTE FORMAT
ADDRESS
WR
ACK
COMMAND
ACK
P
S
ADDRESS
RD
DATA
///
P
7 BITS
8 BITS
7 BITS
8 BITS
COMMAND BYTE: SENDS COM-
MAND WITH NO DATA, USUALLY
USED FOR ONE-SHOT COMMAND
DATA BYTE: READS DATA FROM
THE REGISTER COMMANDED
BY THE LAST READ BYTE OR
WRITE BYTE TRANSMISSION;
ALSO USED FOR SMBus ALERT
RESPONSE RETURN ADDRESS
S = START CONDITION. SHADED = SLAVE TRANSMISSION.
P = STOP CONDITION. /// = NOT ACKNOWLEDGED.
Figure 2. SMBus Protocols
Table 1. Main Temperature Register
(High-Byte) Data Format
Table 2. Extended Resolution Temperature
Register (Low-Byte) Data Format
TEMP (°C)
DIGITAL OUTPUT
0111 1111
0111 1111
0111 1110
0001 1001
0000 0000
0000 0000
1111 1111
TEMP (°C)
DIGITAL OUTPUT
000X XXXX
001X XXXX
010X XXXX
011X XXXX
100X XXXX
101X XXXX
110X XXXX
111X XXXX
> +127
0
+127
+0.125
+0.250
+0.375
+0.500
+0.625
+0.750
+0.875
+126
+25
0
< 0
Diode fault (open or short)
The MAX6693 employs four standard SMBus protocols:
write byte, read byte, send byte, and receive byte
(Figure 2). The shorter receive byte protocol allows
quicker transfers, provided that the correct data regis-
ter was previously selected by a read byte instruction.
Use caution with the shorter protocols in multimaster
systems, since a second master could overwrite the
command byte without informing the first master. Figure
3 is the SMBus write-timing diagram and Figure 4 is the
SMBus read-timing diagram.
data (1 LSB = 1°C). The 8 most significant bits (MSBs)
can be read from the local temperature and remote
temperature registers. The remaining 3 bits for remote
diode 1 can be read from the extended temperature
register. If extended resolution is desired, the extended
resolution register should be read first. This prevents
the most significant bits from being overwritten by new
conversion results until they have been read. If the most
significant bits have not been read within an SMBus
timeout period (nominally 37ms), normal updating con-
tinues. Table 1 shows the main temperature register
(high-byte) data format, and Table 2 shows the extend-
ed resolution register (low-byte) data format.
The remote diode 1 measurement channel provides 11
bits of data (1 LSB = 0.125°C). All other temperature-
measurement channels provide 8 bits of temperature
_______________________________________________________________________________________
9
7-Channel Precision Temperature Monitor
with Beta Compensation
A
B
C
D
E
F
G
H
I
J
K
L
M
t
t
HIGH
LOW
SMBCLK
SMBDATA
t
t
t
t
HD:DAT
HD:STA
SU:STA
SU:DAT
t
t
SU:STO
BUF
MAX693
A = START CONDITION.
F = ACKNOWLEDGE BIT CLOCKED INTO MASTER.
G = MSB OF DATA CLOCKED INTO MASTER.
H = LSB OF DATA CLOCKED INTO MASTER.
I = MASTER PULLS DATA LINE LOW.
J = ACKNOWLEDGE CLOCKED INTO SLAVE.
K = ACKNOWLEDGE CLOCK PULSE.
L = STOP CONDITION.
B = MSB OF ADDRESS CLOCKED INTO SLAVE.
C = LSB OF ADDRESS CLOCKED INTO SLAVE.
D = R/W BIT CLOCKED INTO SLAVE.
M = NEW START CONDITION.
E = SLAVE PULLS SMBDATA LINE LOW.
Figure 3. SMBus Write-Timing Diagram
A
B
C
D
E
F
G
H
I
J
K
L
M
t
t
HIGH
LOW
SMBCLK
SMBDATA
t
t
BUF
SU:STO
t
t
t
SU:DAT
SU:STA HD:STA
A = START CONDITION.
E = SLAVE PULLS SMBDATA LINE LOW.
I = MASTER PULLS DATA LINE LOW.
J = ACKNOWLEDGE CLOCKED INTO SLAVE.
K = ACKNOWLEDGE CLOCK PULSE.
L = STOP CONDITION.
B = MSB OF ADDRESS CLOCKED INTO SLAVE.
C = LSB OF ADDRESS CLOCKED INTO SLAVE.
D = R/W BIT CLOCKED INTO SLAVE.
F = ACKNOWLEDGE BIT CLOCKED INTO MASTER.
G = MSB OF DATA CLOCKED INTO SLAVE.
H = LSB OF DATA CLOCKED INTO SLAVE.
M = NEW START CONDITION.
Figure 4. SMBus Read-Timing Diagram
Diode Fault Detection
(see the OVERT Overtemperature Alarms section). Access
If a channel’s input DXP_ and DXN_ are left open, the
MAX6693 detects a diode fault. An open diode fault does
not cause either ALERT or OVERT to assert. A bit in the sta-
tus register for the corresponding channel is set to 1 and the
temperature data for the channel is stored as all 1s (FFh). It
takes approximately 4ms for the MAX6693 to detect a diode
fault. Once a diode fault is detected, the MAX6693 goes to
the next channel in the conversion sequence.
to these registers is provided through the SMBus interface.
ALERT Interrupt Mode
An ALERT interrupt occurs when the internal or external
temperature reading exceeds a high-temperature limit
(user programmable). The ALERT interrupt output signal
can be cleared by reading the status register(s) associ-
ated with the fault(s) or by successfully responding to an
alert response address transmission by the master. In
both cases, the alert is cleared but is reasserted at the
end of the next conversion if the fault condition still
exists. The interrupt does not halt automatic conversions.
The ALERT output is open-drain so that multiple devices
can share a common interrupt line. All ALERT interrupts
can be masked using the configuration 3 register. The
POR state of these registers is shown in Table 1.
Alarm Threshold Registers
There are 11 alarm threshold registers that store over-tem-
perature ALERT and OVERT threshold values. Seven of
these registers are dedicated to storing one local alert tem-
perature threshold limit and six remote alert temperature
threshold limits (see the ALERT Interrupt Mode section).
The remaining four registers are dedicated to remote chan-
nels 1, 4, 5, and 6 to store overtemperature threshold limits
10 ______________________________________________________________________________________
7-Channel Precision Temperature Monitor
with Beta Compensation
MAX693
Configuration 1 Register
The configuration 1 register (Table 4) has several func-
tions. Bit 7 (MSB) is used to put the MAX6693 either in
software standby mode (STOP) or continuous conver-
sion mode. Bit 6 resets all registers to their POR condi-
tions and then clears itself. Bit 5 disables the SMBus
timeout. Bit 3 enables resistance cancellation on chan-
nel 1. See the Series Resistance Cancellation section
for more details. Bit 2 enables beta compensation on
channel 1. See the Beta Compensation section for more
details. The remaining bits of the configuration 1 regis-
ter are not used. The POR state of this register is 0000
1100 (0Ch).
ALERT Response Address
The SMBus alert response interrupt pointer provides
quick fault identification for simple slave devices that
lack the complex logic needed to be a bus master.
Upon receiving an interrupt signal, the host master can
broadcast a receive byte transmission to the alert
response slave address (see the Slave Address sec-
tion). Then, any slave device that generated an inter-
rupt attempts to identify itself by putting its own
address on the bus.
The alert response can activate several different slave
devices simultaneously, similar to the I2C General Call.
If more than one slave attempts to respond, bus arbitra-
tion rules apply, and the device with the lower address
code wins. The losing device does not generate an
acknowledgment and continues to hold the ALERT line
low until cleared. (The conditions for clearing an alert
vary depending on the type of slave device.)
Successful completion of the alert response protocol
clears the output latch. If the condition that caused the
alert still exists, the MAX6693 reasserts the ALERT
interrupt at the end of the next conversion.
Configuration 2 Register
The configuration 2 register functions are described in
Table 5. Bits [6:0] are used to mask the ALERT interrupt
output. Bit 6 masks the local alert interrupt and bits 5
through bit 0 mask the remote alert interrupts. The
power-up state of this register is 0000 0000 (00h).
Configuration 3 Register
Table 6 describes the configuration 3 register. Bits 5, 4, 3,
and 0 mask the OVERT interrupt output for channels 6, 5,
4, and 1. The remaining bits, 7, 6, 2, and 1, are reserved.
The power-up state of this register is 0000 0000 (00h).
OVERT Overtemperature Alarms
The MAX6693 has four overtemperature registers that
store remote alarm threshold data for the OVERT output.
OVERT is asserted when a channel’s measured temper-
ature is greater than the value stored in the correspond-
ing threshold register. OVERT remains asserted until the
temperature drops below the programmed threshold
minus 4°C hysteresis. An overtemperature output can
be used to activate a cooling fan, send a warning, initi-
ate clock throttling, or trigger a system shutdown to pre-
vent component damage. See Table 3 for the POR state
of the overtemperature threshold registers.
Status Register Functions
Status registers 1, 2, and 3 (Tables 7, 8, and 9) indicate
which (if any) temperature thresholds have been
exceeded and if there is an open-circuit or short-circuit
fault detected with the external sense junctions. Status
register 1 indicates if the measured temperature has
exceeded the threshold limit set in the ALERT registers
for the local or remote-sensing diodes. Status register 2
indicates if the measured temperature has exceeded
the threshold limit set in the OVERT registers. Status
register 3 indicates if there is a diode fault (open or
short) in any of the remote-sensing channels.
Command Byte Functions
The 8-bit command byte register (Table 3) is the master
index that points to the various other registers within the
MAX6693. This register’s POR state is 0000 0000.
Bits in the alert status register clear by a successful
read, but set again after the next conversion unless the
fault is corrected, either by a drop in the measured tem-
perature or an increase in the threshold temperature.
Configuration Byte Functions
There are three read-write configuration registers
(Tables 4, 5, and 6) that can be used to control the
MAX6693’s operation.
The ALERT interrupt output follows the status flag bit.
Once the ALERT output is asserted, it can be
deasserted by either reading status register 1 or by
successfully responding to an alert response address.
In both cases, the alert is cleared even if the fault condi-
______________________________________________________________________________________ 11
7-Channel Precision Temperature Monitor
with Beta Compensation
Table 3. Command Byte Register Bit Assignment
ADDRESS POR STATE READ/
REGISTER
DESCRIPTION
(HEX)
(HEX)
WRITE
Local
07
01
02
03
04
05
06
41
42
43
44
45
46
17
00
00
00
00
00
00
00
0C
00
00
00
00
00
5A
R
R
Read local temperature register
Remote 1
Read channel 1 remote temperature register
Read channel 2 remote temperature register
Read channel 3 remote temperature register
Read channel 4 remote temperature register
Read channel 5 remote temperature register
Read channel 6 remote temperature register
Read/write configuration register 1
Remote 2
R
Remote 3
R
MAX693
Remote 4
R
Remote 5
R
Remote 6
R
Configuration 1
Configuration 2
Configuration 3
Status1
R/W
R/W
R/W
R
Read/write configuration register 2
Read/write configuration register 3
Read status register 1
Status2
R
Read status register 2
Status3
R
Read status register 3
Local ALERT High Limit
R/W
Read/write local alert high-temperature threshold limit register
Read/write channel 1 remote-diode alert high-temperature
threshold limit register
Remote 1 ALERT High Limit
Remote 2 ALERT High Limit
Remote 3 ALERT High Limit
Remote 4 ALERT High Limit
Remote 5 ALERT High Limit
Remote 6 ALERT High Limit
Remote 1 OVERT High Limit
Remote 4 OVERT High Limit
Remote 5 OVERT High Limit
Remote 6 OVERT High Limit
11
12
13
14
15
16
21
24
25
26
6E
7F
64
64
64
64
6E
7F
5A
5A
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Read/write channel 2 remote-diode alert high-temperature
threshold limit register
Read/write channel 3 remote-diode alert high-temperature
threshold limit register
Read/write channel 4 remote-diode alert high-temperature
threshold limit register
Read/write channel 5 remote-diode alert high-temperature
threshold limit register
Read/write channel 6 remote-diode alert high-temperature
threshold limit register
Read/write channel 1 remote-diode overtemperature threshold
limit register
Read/write channel 4 remote-diode overtemperature threshold
limit register
Read/write channel 5 remote-diode overtemperature threshold
limit register
Read/write channel 6 remote-diode overtemperature threshold
limit register
Remote 1 Extended
Temperature
09
0A
00
R
R
Read channel 1 remote-diode extended temperature register
Read manufacturer ID
Manufacturer ID
4D
12 ______________________________________________________________________________________
7-Channel Precision Temperature Monitor
with Beta Compensation
MAX693
Table 4. Configuration 1 Register
POR
STATE
BIT
NAME
FUNCTION
Standby-Mode Control Bit. If STOP is set to logic 1, the MAX6693 stops
converting and enters standby mode.
7 (MSB)
STOP
0
Reset Bit. Set to logic 1 to put the device into its power-on state. This bit is self-
clearing.
6
5
4
POR
0
0
0
TIMEOUT
RESERVED
Timeout Enable Bit. Set to logic 0 to enable SMBus timeout.
Reserved. Must set to 0.
Resistance
cancellation
Resistance Cancellation Bit. When set to logic 1, the MAX6693 cancels series
resistance in the channel 1 thermal diode.
3
2
1
1
Beta Compensation Bit. When set to logic 1, the MAX6693 compensates for low
beta in the channel 1 thermal sensing transistor.
Beta compensation
1
0
Reserved
Reserved
0
0
—
—
Table 5. Configuration 2 Register
POR
STATE
BIT
NAME
FUNCTION
7 (MSB)
Reserved
Mask Local ALERT
Mask ALERT 6
Mask ALERT 5
Mask ALERT 4
Mask ALERT 3
Mask ALERT 2
Mask ALERT 1
0
0
0
0
0
0
0
0
—
6
5
4
3
2
1
0
Local Alert Mask. Set to logic 1 to mask local channel ALERT.
Channel 6 Alert Mask. Set to logic 1 to mask channel 6 ALERT.
Channel 5 Alert Mask. Set to logic 1 to mask channel 5 ALERT.
Channel 4 Alert Mask. Set to logic 1 to mask channel 4 ALERT.
Channel 3 Alert Mask. Set to logic 1 to mask channel 3 ALERT.
Channel 2 Alert Mask. Set to logic 1 to mask channel 2 ALERT.
Channel 1 Alert Mask. Set to logic 1 to mask channel 1 ALERT.
Effect of Ideality Factor
The accuracy of the remote temperature measure-
ments depends on the ideality factor (n) of the remote
“diode” (actually a transistor). The MAX6693 is opti-
mized for n = 1.006 (channel 1) and n = 1.008 (chan-
nels 2–6). A thermal diode on the substrate of an IC is
normally a pnp with the base and emitter brought out to
the collector (diode connection) grounded. DXP_ must
be connected to the anode (emitter) and DXN_ must be
connected to the cathode (base) of this pnp. If a sense
transistor with an ideality factor other than 1.006 or
1.008 is used, the output data is different from the data
obtained with the optimum ideality factor. Fortunately,
the difference is predictable. Assume a remote-diode
tion exists, but the ALERT output reasserts at the end of
the next conversion. The bits indicating the fault for the
OVERT interrupt output clear only on reading the status 2
register even if the fault conditions still exist. Reading the
status 2 register does not clear the OVERT interrupt out-
put. To eliminate the fault condition, either the measured
temperature must drop below the temperature threshold
minus the hysteresis value (4°C), or the trip temperature
must be set at least 4°C above the current temperature.
Applications Information
Remote-Diode Selection
The MAX6693 directly measures the die temperature of
CPUs and other ICs that have on-chip temperature-
sensing diodes (see the Typical Application Circuit) or
it can measure the temperature of a discrete diode-
connected transistor.
sensor designed for a nominal ideality factor n
NOMINAL
is used to measure the temperature of a diode with a
different ideality factor n1. The measured temperature
T
M
can be corrected using:
______________________________________________________________________________________ 13
7-Channel Precision Temperature Monitor
with Beta Compensation
Table 6. Configuration 3 Register
POR
STATE
BIT
NAME
FUNCTION
7 (MSB)
6
Reserved
Reserved
0
0
—
—
Channel 6 Remote-Diode OVERT Mask Bit. Set to logic 1 to mask channel 6
OVERT.
5
4
3
Mask OVERT 6
Mask OVERT 5
Mask OVERT 4
0
0
0
MAX693
Channel 5 Remote-Diode OVERT Mask Bit. Set to logic 1 to mask channel 5
OVERT.
Channel 4 Remote-Diode OVERT Mask Bit. Set to logic 1 to mask channel 4
OVERT.
2
1
Reserved
Reserved
0
0
—
—
Channel 1 Remote-Diode OVERT Mask Bit. Set to logic 1 to mask channel 1
OVERT.
0
Mask OVERT 1
0
Beta Compensation
The MAX6693 is optimized for use with a substrate PNP
remote-sensing transistor on the die of the target IC.
DXP1 connects to the emitter of the sensing transistor
⎛
⎞
n
1
T
= T
ACTUAL
M
⎜
⎟
n
⎝
⎠
NOMINAL
where temperature is measured in Kelvin and
for channel 1 of the MAX6693 is 1.009. As
an example, assume you want to use the MAX6693 with
a CPU that has an ideality factor of 1.002. If the diode
has no series resistance, the measured data is related
to the real temperature as follows:
and DXN1 connects to the base. The collector is
grounded. Such transistors can have very low beta
(less than 1) when built in processes with 65nm and
smaller geometries. Because of the very low beta, stan-
dard “remote diode” temperature sensors may exhibit
large errors when used with these transistors. Channel
1 of the MAX6693 incorporates a beta compensation
function that, when enabled, eliminates the effect of low
beta values. This function is enabled at power-up using
bit 2 of the configuration register. Whenever low beta
compensation is enabled, series-resistance cancella-
tion must be enabled.
n
NOMIMAL
⎛
⎞
⎟
n
1.009
1.002
⎛
⎞
NOMINAL
T
= T
×
= T
×
= T (1.00699)
M
⎜
⎝
⎟
⎠
ACTUAL
M
M
⎜
n
1
⎝
⎠
For a real temperature of +85°C (358.15K), the mea-
sured temperature is +84.41°C (357.56K), an error of
-0.590°C.
Discrete Remote Diodes
When the remote-sensing diode is a discrete transistor,
its collector and base must be connected together.
Table 10 lists examples of discrete transistors that are
appropriate for use with the MAX6693. The transistor
must be a small-signal type with a relatively high for-
ward voltage; otherwise, the A/D input voltage range
can be violated. The forward voltage at the highest
expected temperature must be greater than 0.25V at
10µA, and at the lowest expected temperature, the for-
ward voltage must be less than 0.95V at 100µA. Large
power transistors must not be used. Also, ensure that
the base resistance is less than 100Ω. Tight specifica-
tions for forward current gain (50 < ß < 150, for exam-
ple) indicate that the manufacturer has good process
Series Resistance Cancellation
Some thermal diodes on high-power ICs can have
excessive series resistance, which can cause tempera-
ture measurement errors with conventional remote tem-
perature sensors. Channel 1 of the MAX6693 has a
series resistance cancellation feature (enabled by bit 3
of the configuration 1 register) that eliminates the effect
of diode series resistance. Set bit 3 to 1 if the series
resistance is large enough to affect the accuracy of
channel 1. The series resistance cancellation function
increases the conversion time for channel 1 by 125ms.
This feature cancels the bulk resistance of the sensor
and any other resistance in series (wire, contact resis-
tance, etc.). The cancellation range is from 0Ω to 100Ω.
controls and that the devices have consistent V char-
BE
14 ______________________________________________________________________________________
7-Channel Precision Temperature Monitor
with Beta Compensation
MAX693
Table 7. Status 1 Register
POR
STATE
BIT
NAME
FUNCTION
7 (MSB)
Reserved
0
0
—
Local Channel High-Alert Bit. This bit is set to logic 1 when the local
temperature exceeds the temperature threshold limit in the local ALERT high-
limit register.
6
5
4
3
2
1
0
Local ALERT
Channel 6 Remote-Diode High-Alert Bit. This bit is set to logic 1 when the
channel 6 remote-diode temperature exceeds the temperature threshold limit
in the remote 6 ALERT high-limit register.
Remote 6 ALERT
Remote 5 ALERT
Remote 4 ALERT
Remote 3 ALERT
Remote 2 ALERT
Remote 1 ALERT
0
0
0
0
0
0
Channel 5 Remote-Diode High-Alert Bit. This bit is set to logic 1 when the
channel 5 remote-diode temperature exceeds the programmed temperature
threshold limit in the remote 5 ALERT high-limit register.
Channel 4 Remote-Diode High-Alert Bit. This bit is set to logic 1 when the
channel 4 remote-diode temperature exceeds the temperature threshold limit
in the remote 4 ALERT high-limit register.
Channel 3 Remote-Diode High-Alert Bit. This bit is set to logic 1 when the
channel 3 remote-diode temperature exceeds the programmed temperature
threshold limit in the remote 3 ALERT high-limit register.
Channel 2 Remote-Diode High-Alert Bit. This bit is set to logic 1 when the
channel 2 remote-diode temperature exceeds the temperature threshold limit
in the remote 2 ALERT high-limit register.
Channel 1 Remote-Diode High-Alert Bit. This bit is set to logic 1 when the
channel 1 remote-diode temperature exceeds the temperature threshold limit
in the remote 1 ALERT high-limit register.
acteristics. Manufacturers of discrete transistors do not
normally specify or guarantee ideality factor. This is
normally not a problem since good-quality discrete
transistors tend to have ideality factors that fall within a
relatively narrow range. We have observed variations in
remote temperature readings of less than 2°C with a
variety of discrete transistors. Still, it is good design
practice to verify good consistency of temperature
readings with several discrete transistors from any
manufacturer under consideration.
unused channels immediately upon power-up by set-
ting the appropriate bits in the Configuration 2 and
Configuration 3 registers. This will prevent unused
channels from causing ALERT or OVERT to assert.
Thermal Mass and Self-Heating
When sensing local temperature, the MAX6693 mea-
sures the temperature of the PCB to which it is soldered.
The leads provide a good thermal path between the
PCB traces and the die. As with all IC temperature sen-
sors, thermal conductivity between the die and the
ambient air is poor by comparison, making air tempera-
ture measurements impractical. Because the thermal
mass of the PCB is far greater than that of the
MAX6693, the device follows temperature changes on
the PCB with little or no perceivable delay. When mea-
suring the temperature of a CPU or other IC with an on-
chip sense junction, thermal mass has virtually no
Unused Diode Channels
If one or more of the remote diode channels is not
needed, disconnect the DXP and DXN inputs for that
channel, or connect the DXP input to V . The status
CC
register indicates a diode "fault" for this channel and the
channel is ignored during the temperature-measure-
ment sequence. It is also good practice to mask any
______________________________________________________________________________________ 15
7-Channel Precision Temperature Monitor
with Beta Compensation
Table 8. Status 2 Register
POR
STATE
BIT
NAME
FUNCTION
7 (MSB)
6
Reserved
Reserved
0
0
—
—
Channel 6 Remote-Diode Overtemperature Status Bit. This bit is set to logic 1
when the channel 6 remote-diode temperature exceeds the temperature
threshold limit in the remote 6 OVERT high-limit register.
5
4
3
Remote 6 OVERT
Remote 5 OVERT
Remote 4 OVERT
0
0
0
MAX693
Channel 5 Remote Diode Overtemperature Status Bit. This bit is set to logic 1
when the channel 5 remote-diode temperature exceeds the temperature
threshold limit in the remote 5 OVERT high-limit register.
Channel 4 Remote Diode Overtemperature Status Bit. This bit is set to logic 1
when the channel 4 remote-diode temperature exceeds the temperature
threshold limit in the remote 4 OVERT high-limit register.
2
1
Reserved
Reserved
0
0
—
—
Channel 1 Remote-Diode Overtemperature Status Bit. This bit is set to logic 1
when the channel 1 remote-diode temperature exceeds the temperature
threshold limit in the remote 1 OVERT high-limit register.
0
Remote 1 OVERT
0
Table 9. Status 3 Register
POR
STATE
BIT
7 (MSB)
6
NAME
Reserved
FUNCTION
0
—
Channel 6 Remote-Diode Fault Bit. This bit is set to 1 when DXP6 and DXN6
are open circuit or when DXP6 is connected to V
Diode fault 6
0
.
CC
Channel 5 Remote-Diode Fault Bit. This bit is set to 1 when DXP5 and DXN5
are open circuit or when DXP5 is connected to V
5
4
3
2
Diode fault 5
Diode fault 4
Diode fault 3
Diode fault 2
0
0
0
0
.
CC
Channel 4 Remote-Diode Fault Bit. This bit is set to 1 when DXP4 and DXN4
are open circuit or when DXP4 is connected to V
.
CC
Channel 3 Remote-Diode Fault Bit. This bit is set to 1 when DXP3 and DXN3
are open circuit or when DXP3 is connected to V
.
CC
Channel 2 Remote-Diode Fault Bit. This bit is set to 1 when DXP2 and DXN2
are open circuit or when DXP2 is connected to V
.
CC
Channel 1 Remote-Diode Fault Bit. This bit is set to 1 when DXP1 and DXN1
1
0
Diode fault 1
Reserved
0
0
are open circuit or when DXP1 is connected to V
.
CC
—
16 ______________________________________________________________________________________
7-Channel Precision Temperature Monitor
with Beta Compensation
MAX693
effect; the measured temperature of the junction tracks
the actual temperature within a conversion cycle.
Follow these guidelines to reduce the measurement
error when measuring remote temperature:
When measuring temperature with discrete remote tran-
sistors, the best thermal response times are obtained
with transistors in small packages (i.e., SOT23 or SC70).
Take care to account for thermal gradients between the
heat source and the sensor, and ensure that stray air
currents across the sensor package do not interfere with
measurement accuracy. Self-heating does not signifi-
cantly affect measurement accuracy. Remote-sensor
self-heating due to the diode current source is negligible.
1) Place the MAX6693 as close as is practical to the
remote diode. In noisy environments, such as a com-
puter motherboard, this distance can be 4in to 8in
(typ). This length can be increased if the worst noise
sources are avoided. Noise sources include CRTs,
clock generators, memory buses, and PCI buses.
2) Do not route the DXP-DXN lines next to the deflec-
tion coils of a CRT. Also, do not route the traces
across fast digital signals, which can easily intro-
duce +30°C error, even with good filtering.
ADC Noise Filtering
The integrating ADC has good noise rejection for low-
frequency signals, such as power-supply hum. In environ-
ments with significant high-frequency EMI, connect an
external 100pF capacitor between DXP_ and DXN_.
Larger capacitor values can be used for added filtering,
but do not exceed 100pF because it can introduce errors
due to the rise time of the switched current source. High-
frequency noise reduction is needed for high-accuracy
remote measurements. Noise can be reduced with careful
PCB layout as discussed in the PCB Layout section.
3) Route the DXP and DXN traces in parallel and in close
proximity to each other. Each parallel pair of traces
should go to a remote diode. Route these traces away
from any higher voltage traces, such as +12VDC.
Leakage currents from PCB contamination must be
dealt with carefully since a 20MΩ leakage path from
DXP to ground causes about +1°C error. If high-volt-
age traces are unavoidable, connect guard traces to
GND on either side of the DXP-DXN traces (Figure 5).
4) Route through as few vias and crossunders as possi-
ble to minimize copper/solder thermocouple effects.
Slave Address
The slave address for the MAX6693 is shown in Table 11.
Table 10. Remote-Sensors Transistor
Manufacturer (for Channels 2–6)
5) Use wide traces when practical. 5mil to 10mil traces
are typical. Be aware of the effect of trace resistance on
temperature readings when using long, narrow traces.
6) When the power supply is noisy, add a resistor (up
MANUFACTURER
Central Semiconductor (USA)
Rohm Semiconductor (USA)
Samsung (Korea)
MODEL NO.
to 47Ω) in series with V
.
CC
CMPT3904
SST3904
KST3904-TF
SMBT3904
GND
Siemens (Germany)
5–10 mils
MINIMUM
5–10 mils
Zetex (England)
FMMT3904CT-ND
5–10 mils
5–10 mils
DXP
Note: Discrete transistors must be diode connected (base
shorted to collector).
DXN
GND
PCB Layout
Table 11. Slave Address
DEVICE ADDRESS
Figure 5. Recommended DXP-DXN PCB Traces. The two outer
guard traces are recommended if high-voltage traces near the
DXN and DXP traces.
A7
A6
A5
A4
A3
A2
A1
A0
1
0
0
1
1
0
1
R/W
______________________________________________________________________________________ 17
7-Channel Precision Temperature Monitor
with Beta Compensation
device, connect the twisted pair to DXP and DXN and
Twisted-Pair and Shielded Cables
Use a twisted-pair cable to connect the remote sensor
for remote-sensor distances longer than 8in or in very
noisy environments. Twisted-pair cable lengths can be
between 6ft and 12ft before noise introduces excessive
errors. For longer distances, the best solution is a
shielded twisted pair like that used for audio micro-
phones. For example, Belden #8451 works well for dis-
tances up to 100ft in a noisy environment. At the
the shield to GND. Leave the shield unconnected at the
remote sensor. For very long cable runs, the cable’s
parasitic capacitance often provides noise filtering, so
the 100pF capacitor can often be removed or reduced
in value. Cable resistance also affects remote-sensor
accuracy. For every 1Ω of series resistance the error is
approximately +0.5°C.
MAX693
Pin Configuration
TOP VIEW
+
DXP1
DXN1
DXP2
DXN2
DXP3
DXN3
DXP4
DXN4
DXP5
1
2
3
4
5
6
7
8
9
20 GND
19 SMBCLK
18 SMBDATA
17 ALERT
MAX6693
16
15 OVERT
14
V
CC
N.C.
13 STBY
12 DXP6
11 DXN6
DXN5 10
TSSOP
Chip Information
PROCESS: BiCMOS
18 ______________________________________________________________________________________
7-Channel Precision Temperature Monitor
with Beta Compensation
MAX693
Package Information
For the latest package outline information, go to www.maxim-ic.com/packages.
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
21-0066
20 TSSOP
U20-2
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 19
© 2008 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
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