NCT75MNR2G [ONSEMI]
Industry Standard Digital Temperature Sensor with 2âwire Interface; 行业标准数字温度传感器，具有2A ????线接口
| 型号： | NCT75MNR2G |
| 厂家： | 
ONSEMI |
| 描述： | Industry Standard Digital Temperature Sensor with 2âwire Interface |
| 文件： | 总14页 (文件大小：216K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
NCT75
Industry Standard Digital
Temperature Sensor with
2‐wire Interface
The NCT75 is a two-wire serially programmable temperature
sensor with an over-temperature/interrupt output pin to signal out of
limit conditions. This is an open-drain pin and can operate in either
comparator or interrupt mode. Temperature measurements are
converted into digital form using a high resolution (12 bit),
sigma-delta, analog-to-digital converter (ADC). The device operates
over the –55C to +125C temperature range.
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DFN8
CASE 506AA
SOIC8
CASE 751
Micro8t
Communication with the NCT75 is accomplished via the
CASE 846A
2
SMBus/I C interface. Three address selection pins, A2, A1 and A0,
can be used to connect up to 8 NCT75s to a single bus. Through this
interface the NCT75s internal registers may be accessed. These
registers allow the user to read the current temperature, change the
configuration settings and adjust the temperature limits.
The NCT75 has a wide supply voltage range of 3.0 V to 5.5 V. The
average supply current is 575 mA at 3.3 V. It also offers a shutdown
mode to conserve power. The typical shutdown current is 3 mA.
The NCT75 is available in three, space saving packages – 8-lead
DFN, 8-lead Micro8t and 8-lead SOIC and is also fully pin and
register compatible with the LM75 and TCN75.
PIN ASSIGNMENT
1
2
3
4
8
7
6
5
SDA
SCL
V
DD
A0
(Top View)
OS/ALERT
GND
A1
A2
MARKING DIAGRAMS
8
Features
1
XXXX
XXMG
12-bit Temperature-to-Digital Converter
Input Voltage Range from 3.0 V to 5.5 V
Temperature Range from −55C to +125C
SMBus/I C Interface
Overtemperature Indicator
Support for SMBus/ALERT
Shutdown Mode for Low Power Consumption
One-shot Mode
Available in 8-pin DFN, 8-pin Micro8t and SOIC Packages
These Devices are Pb-Free, Halogen Free/BFR Free and are RoHS
Compliant
AYWG
G
G
1
DFN8
Micro8t
XXXX = Specific Device Code
2
M
A
Y
W
G
= Date Code
= Assembly Location
= Year
= Work Week
= Pb-Free Package
(Note: Microdot may be in either location)
8
XXXXX
ALYWX
Applications
Computer Thermal Monitoring
Thermal Protection
Isolated Sensors
Battery Management
Office Electronics
G
1
SOIC8
XXXXX = Specific Device Code
A
L
= Assembly Location
= Wafer Lot
Y
W
G
= Year
= Work Week
= Pb-Free Package
Electronic Test Equipment
Thermostat Controls
System Thermal Management
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 11 of this data sheet.
Semiconductor Components Industries, LLC, 2012
1
Publication Order Number:
August, 2012 − Rev. 3
NCT75/D
NCT75
8
V
DD
1
2
SDA
SCL
REGISTERS
CONFIGURATION
TWO-WIRE
INTERFACE
T
HYST
5
6
7
A2
A1
A0
3
TEMPERATURE
ONE-SHOT
T
OS
OS/ALERT
DELTA-SIGMA
ADC
CONTROL
LOGIC
4
GND
Figure 1. Simplified Block Diagram
V
DD
3.0 V To 5.5 V
C
BYPASS
5
6
7
A2
A1
A0
ADDRESS
(SET AS DESIRED)
1
2
SDA
SCL
NCT75
SERIAL INTERFACE
3
OS/ALERT
NOTE: SDA, SCL AND OS/ALERT PINS
REQUIRE PULL-UP RESISTORS TO V
DD
4
GND
Figure 2. Typical Application Circuit
Table 1. PIN FUNCTION DESCRIPTION
Pin No.
Pin Name
SDA
Description
2
1
2
3
4
5
6
7
8
SMBus/I C Serial Bi-directional Data Input/Output. Open-drain pin; needs a pull-up resistor.
Serial Clock Input. Open-drain pin; needs a pull-up resistor.
SCL
OS/ALERT
GND
A2
Over-temperature Indicator. Open-drain output; needs a pullup resistor. Active Low output.
Power Supply Ground.
2
2
SMBus/I C Serial Bus Address Selection Pin. Connect to GND or V to set the desired I C address.
DD
2
2
A1
SMBus/I C Serial Bus Address Selection Pin. Connect to GND or V to set the desired I C address.
DD
2
2
A0
SMBus/I C Serial Bus Address Selection Pin. Connect to GND or V to set the desired I C address.
DD
V
DD
Positive Supply Voltage, 3.0 V to 5.5 V. Bypass to ground with a 0.1 mF bypass capacitor.
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NCT75
Table 2. ABSOLUTE MAXIMUM RATINGS (Note 1)
Rating
Symbol
Value
Unit
V
Supply Voltage
V
DD
−0.3 to +7
Input Voltage on SCL, SDA, A2, A1, A0 and OS/ALERT.
Input Current on SDA, A2, A1, A0 and OS/ALERT.
Maximum Junction Temperature
−0.3 to V + 0.3
V
DD
I
−1 to +50
150.7
mA
C
C
C
V
IN
T
J(max)
Operating Temperature Range
T
OP
−55 to 125
−65 to 160
2,000
Storage Temperature Range
T
STG
ESD Capability, Human Body Model (Note 2)
ESD Capability, Machine Model (Note 2)
ESD
HBM
ESD
400
V
MM
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
1. Refer to ELECTRICAL CHARACTERISTICS and APPLICATION INFORMATION for Safe Operating Area.
2. This device series incorporates ESD protection and is tested by the following methods:
ESD Human Body Model tested per AEC−Q100−002 (EIA/JESD22−A114)
ESD Machine Model tested per AEC−Q100−003 (EIA/JESD22−A115)
Table 3. OPERATING RANGES (Note 3)
Rating
Symbol
Min
3.0
Max
5.5
Unit
V
Operating Supply Voltage
Operating Ambient Temperature Range
V
IN
T
A
−55
125
C
3. Refer to ELECTRICAL CHARACTERISTICS and APPLICATION INFORMATION for Safe Operating Area.
Table 4. SMBus TIMING SPECIFICATIONS
Parameter
Serial Clock Frequency
Start Condition Hold Time
Stop Condition Setup Time
Clock Low Period
Symbol
Test Conditions
Min
DC
0.6
100
1.3
0.6
100
100
0
Typ
−
Max
400
−
Unit
f
kHz
ms
ns
ms
ms
ns
ns
ns
ns
ns
ms
ms
SCL
t
−
HD:STA
SU:STO
t
90% of SCL to 10% of SDA
−
−
t
−
−
LOW
Clock High Period
t
−
−
HIGH
Start Condition Setup Time
Data Setup Time
t
90% of SCL to 90% of SDA
10% of SDA to 10% of SCL
10% of SCL to 10% of SDA
−
−
SU:STA
SU:DAT
HD:DAT
t
−
−
Data Hold Time (Note 4)
SDA/SCL Rise Time
t
−
76
−
t
R
−
300
300
−
SDA/SCL Fall Time
t
F
−
−
Minimum RESET Pulse Width
t
1.3
1.3
−
RESET
Bus Free Time Between STOP
and START Conditions
t
−
−
BUF
4. This refers to the hold time when the NCT75 is writing data to the bus.
t
R
t
F
t
HD;STA
t
LOW
SCL
SDA
t
HIGH
t
t
SU;STA
HD;STA
t
SU;STO
t
t
HD;DAT
SU;DAT
t
BUF
STOP START
STOP
START
Figure 3. Serial Interface Timing
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NCT75
Table 5. ELECTRICAL CHARACTERISTICS
(T = T
to T , V = 3.0 V to 5.5 V. All specifications for −55C to +125C, unless otherwise noted.)
MAX DD
A
MIN
Parameter
TEMPERATURE SENSOR AND ADC
Test Conditions
Min
Typ
Max
Unit
Accuracy at V = 3.0 V to 5.5 V
T = 0C to +70C
−
−
−
−
−
−
1
2
3
C
DD
A
T = −25C to +100C
A
T = −55C to +125C
A
ADC Resolution
−
−
−
−
12
0.0625
48.5
80
−
−
−
−
Bits
C
Temperature Resolution
Temperature Conversion Time
Update Rate
One-shot Mode
ms
ms
POWER REQUIREMENTS
Supply Voltage
3.0
2.75
−
−
−
−
5.5
−
V
V
POR Threshold
2
Supply Current
Peak Current while Converting and I C
Interface Inactive
0.8
mA
Average Current
Average Current over 1 Conversion Cycle
Supply Current in Shutdown Mode
−
−
0.44
3
0.575
12
mA
Shutdown Mode at 3.3 V
OS/ALERT OUTPUT (OPEN DRAIN)
mA
Output Low Voltage, V
Pin Capacitance
I
= 4 mA
−
−
−
0.15
10
0.4
−
V
OL
OL
pF
mA
High Output Leakage Current, IOH
DIGITAL INPUTS (SDA, SCL)
Input Current
OS/ALERT Pin Pulled Up to 5.5 V
0.1
5
V
V
V
= 0 V to V
−
−
−
−
−
−
1
mA
V
IN
DD
Input Low Voltage, V
= 3.3 V (Note 5)
= 3.3 V (Note 5)
0.3 x V
DD
IL
DD
DD
Input High Voltage, V
0.7xV
−
V
IH
DD
SCL, SDA Glitch Rejection
Input Filtering Suppresses Noise Spikes of
Less than 50 ns
−
50
ns
Pin Capacitance
−
3
−
pF
DIGITAL OUTPUT (SDA) (OPEN DRAIN)
Output High Current, I
V
= 5 V
−
−
−
−
−
3
1
0.4
−
mA
V
OH
OH
Output Low Voltage, V
I
OL
= 3 mA
OL
Output Capacitance, C
pF
OUT
5. Guaranteed by characterization, not production tested.
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NCT75
APPLICATION INFORMATION
Functional Description
While the ADC of the NCT75 can theoretically measure
temperatures in the range of −128C to 127C, the NCT75
is guaranteed to measure from −55C to +125C.
Table 6 shows the relevant temperature bits for a 12 bit
temperature reading. A 2-byte read is required to obtain the
full 12 bit temperature reading. If an 8 bit (1C resolution)
reading is required then a single byte read is sufficient.
The NCT75 temperature sensor converts an analog
temperature measurement to a digital representation by
using an on-chip measurement transistor and a 12 bit
Delta-Sigma ADC.
The device includes an open drain ALERT output which
can be used to signal that the programmed temperature limit
has been exceeded.
The two main modes of operation are normal and
shutdown mode. In normal mode the NCT75 performs
a new temperature conversion every 80 ms. This new value
is then updated to the temperature value register
Table 6. 12-BIT TEMPERATURE DATA FORMAT
Binary Value
D15 to D4
Temperature
−55C
Hex Value
0xC90
0xE70
0xFFF
0x000
0x001
0x190
0x4B4
0x640
0x7D0
1100 1001 0000
1110 0111 0000
1111 1111 1111
0000 0000 0000
0000 0000 0001
0001 1001 0000
0100 1011 0100
0110 0100 0000
0111 1101 0000
(address 0x00) and also compared to the T register limit
OS
−25C
(default = 80C). If the temperature value register is read
during the conversion sequence the value returned is the
previously stored value. A bus read does not affect the
conversion that is in progress.
−0.0625C
0C
+0.0625C
+25C
In shutdown mode temperature conversion is disabled and
the temperature value register holds the last valid
temperature reading. The NCT75 can still be communicated
with in this mode as the interface is still active. The device
mode is controlled via bit 0 of the configuration register.
While in shutdown mode a conversion can be initiated by
writing an arbitrary value to the one-shot register (0x04).
This has the effect of powering up the NCT75, performing
a conversion, comparing the new temperature with the
programmed limit and then going back into shutdown mode.
The OS/ALERT pin can be configured in many ways to
allow it to be used in many different system configurations.
The overtemperature output can be configured to operate
as a comparator type output (which is self clearing once the
temperature has returned below the hysteresis value) or an
interrupt type output (which requires the master to read an
internal register AND the temperature to return below the
hysteresis value before going into an inactive state). The
ALERT pin can also be configured as an active high or active
low output.
+75.25C
+100C
+125C
Temperature Data Conversion
12-bit Temperature Data Format
Positive Temperature = ADC Code (decimal)/16
Example 190h = 400d/16 = +25C
Negative Temperature = (ADC Code(decimal) − 4096)/16
Example E70h = (3696d – 4096)/16 = −25C
One-shot Mode
One of the features of the NCT75 is a One-shot
Temperature Measurement Mode. This mode is useful if
reduced power consumption is a design requirement.
To enable one-shot mode bit 5 of the configuration
register needs to be set. Once, enabled, the NCT75 goes
immediately into shutdown mode. Here, the current
consumption is reduced to a typical value of 3 mA. Writing
address 0x04 to the address pointer register initiates a
one-shot temperature measurement. This powers up the
NCT75, carries out a temperature measurement, and then
powers down again. The data written to this register is
irrelevant and is not stored. It is the write operation that
causes the one-shot conversion.
Temperature Measurement Results
The results of the on chip temperature measurements are
stored in the temperature value register and compared with
the T and T
limit register.
OS
HYST
The temperature value, T and T
registers are
OS
HYST
16 bits wide and have a resolution of 0.0625C. The data is
stored as a 12 bit 2s complement word. The data is left
justified, D15 is the MSB and is the sign bit. The four LSBs
(D3 to D0) are always 0 as they are not part of the result.
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NCT75
Registers
The NCT75 contains six registers for configuring and
reading the teperature: the address pointer register, 4 data
registers and a one-shot register. The configuration register,
the address pointer register and the one-shot register are all
82C
81C
80C
79C
78C
77C
76C
75C
74C
73C
72C
T
OS
8 bits wide while the temperature register, T
and T
HYST
OS
registers are all 16 bits wide. All registers, except for the
temperature register, can be be read from and written to (the
temperature register is read only). The power on state and
address of each register are listed in Table 9.
T
HYST
Address Pointer Register
The address pointer register is used to select which
register is to respond to a read or write operation. The three
LSBs (P2, P1 & P0) of this write only register are used to
select the appropriate register. On power up this register is
loaded with a value of 0x00 and so points to the temperature
register. Table 7 shows the bits of the address pointer register
and Table 8 shows the pointer address selecting each of the
registers available.
OS/ALERT PIN
(COMPARATOR MODE)
POLARITY = 0
OS/ALERT PIN
(INTERRUPT MODE)
POLARITY = 0
Table 7. ADDRESS POINTER REGISTER
OS/ALERT PIN
(COMPARATOR MODE)
POLARITY = 1
P7
P6
P5
P4
P3
P2
P1
P0
Default
0
0
0
0
0
0
0
0
OS/ALERT PIN
(INTERRUPT MODE)
POLARITY = 1
Table 8. REGISTER ADDRESSES SELECTION
P2
0
P1
0
P0
0
Register Selected
Stored Temperature
Configuration
0
0
1
Figure 4. One-shot OS/ALERT Pin Operation
Fault Queue
A fault is defined as when the temperature exceeds
a pre-defined temperature limit. This limit can be
0
1
0
T
Setpoint
HYST
0
1
1
T Setpoint
OS
1
0
0
One-shot
Table 9. NCT75 REGISTER SET
programmed in the T
and the T setpoint registers.
HYST
OS
Power-on
Default Value
Bits 3 and 4 of the configuration register determine the
number of faults necessary to trigger the OS/ALERT pin. Up
to six faults can be programmed to prevent false tripping
when the NCT75 is used in a noisy temperature
environment. In order for the OS/ALERT output to be set
these faults must occur consecutively.
Register
Address
Hex
0x0000
0x00
5C
0
Register Name
0x00 (R)
Stored Temperature Value
Configuration
0x01 (R/W)
0x02 (R/W)
0x03 (R/W)
0x04 (R/W)
−
T
T
0x4B00
0x5000
0xXX
75
80
−
HYST
OS
One-shot
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NCT75
Temperature Register
The temperature measured by the parts internal sensor is
stored in this 16-bit read only register. The data is stored in
twos complement format with the MSB as the sign bit. The
8 MSBs must be read frist followed by the 8 LSBs.
Table 10. TEMPERATURE VALUE REGISTER
MSB
LSB
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
0
0
0
0
0
0
0
0
0
0
0
0
X
X
X
X
Configuration Register
D[4:3]: Fault Queue
This 8-bit read/write register is used to configure the
NCT75 into its various modes of operation. The different
modes are listed in Table 11 and explained in more detail
below.
D4 D3 These two bits determine how many
overtemperature conditions occur before the OS/Alert
pin is triggered. This helps to prevent false triggering of
the output.
0
0
1
2
0 = 1 Fault (Default)
1 = 2 Faults
0 = 4 Faults
Table 11. CONFIGURATION REGISTER
Bit
D7
D6
D5
D4
D3
D2
D1
D0
Configuration
Reserved
Default Value
1 = 6 Faults
0
0
0
0
0
0
0
0
Reserved
D2: OS/Alert pin polarity
This selects the polarity of the OS/Alert output pin.
D2 = 0 Output is active low. (Default)
D2 = 1 Output is active high.
One-shot Mode
Fault-queue
Fault-queue
D1: Cmp/Int
OS/ALERT Pin Polarity
Cmp/Int Mode
Shutdown Mode
D1 = 0 Comparator mode. (Default)
D1 = 1 Interrupt mode.
D0: Shutdown
D7: Reserved
D0 = 0 Normal mode – part is fully powered. (Default)
D0 = 1 Shutdown mode – all circuitry except for the
SMBus interface is powered down. Write a 0 to this bit to
power up again.
Write 0 to this bit.
D6: Reserved
Write 0 to this bit.
D5: One-shot Mode
THYST Register
D5 = 0 Part is in normal mode and converting every
60 ms. (Default)
The T
register stores the temperature hysteresis
HYST
value for the overtemperature output. This value is picked to
stop the OS/Alert pin from being asserted and de-asserted in
noisy temperature environments. This limit is stored in the
16 bit register in twos complement format. The MSB is the
temperature sign bit. The 8 MSBs must be read first
followed by the 8 LSBs. The default value is +75C.
D5 = 1 Setting this bit puts the part into one-shot mode.
The part is normally powered down in this mode until the
one shot register is written to. Once this register is written
to one conversion is performed and the part returns to its
shutdown state.
Table 12. THYST REGISTER
MSB
LSB
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
0
1
0
0
1
0
1
1
0
0
0
0
X
X
X
X
TOS Register
This register stores the temperature limit at which the part
asserts an OS/Alert. Once the measured temperature reaches
this value an alert or overtemperature output is generated.
The data is stored in twos complement format with the MSB
as the sign bit. The 8 MSBs must be read frist followed by
the 8 LSBs. The default limit +80C.
Table 13. TOS REGISTER
MSB
LSB
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
0
1
0
1
0
0
0
0
0
0
0
0
X
X
X
X
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NCT75
Serial Interface
master writes to the slave device. If the R/W bit is
a one then the master reads from the slave device.
2. Data is sent over the serial bus in sequences of
nine clock pulses, eight bits of data followed by an
acknowledge bit from the receiver of data.
Transitions on the data line must occur during the
low period of the clock signal and remain stable
during the high period, since a low-to-high
transition when the clock is high can be interpreted
as a stop signal.
3. When all data bytes have been read or written,
stop conditions are established. In write mode, the
master pulls the data line high during the tenth
clock pulse to assert a stop condition. In read
mode, the master overrides the acknowledge bit by
pulling the data line high during the low period
before the ninth clock pulse. This is known as no
acknowledge. The master takes the data line low
during the low period before the tenth clock pulse,
then high during the tenth clock pulse to assert a
stop condition.
2
Control of the NCT75 is carried out via the SMBus/I C
compatible serial interface. The NCT75 is connected to this
bus as a slave device, under the control of a master device.
Serial Bus Address
Control of the NCT75 is carried out via the serial bus. The
NCT75 is connected to this bus as a slave device under the
control of a master device. The NCT75 has a 7-bit serial
address. The four MSBs are fixed and set to 1001 while the
3 LSBs can be configured by the user using pins 5, 6 and 7
(A2, A1 and A0). Each of these pins can be configured in one
of two ways low or high. This gives eight different address
options listed in Table 14 below. The state of these pins is
continually sampled and so can be changed after power up.
Table 14. SERIAL BUS ADDRESS OPTIONS
MSBs
LSBs
Address
Hex
A6
1
A5
A4
0
A3
1
A2
0
A1
0
A0
0
0
0
0
0
0
0
0
0
0x48
1
0
1
0
0
1
0x49
1
0
1
0
1
0
0x4A
0x4B
0x4C
0x4D
0x4E
0x4F
Any number of bytes of data can be transferred over the
serial bus in one operation. However, it is not possible to mix
read and write in one operation because the type of operation
is determined at the beginning and cannot subsequently be
changed without starting a new operation.
1
0
1
0
1
1
1
0
1
1
0
0
1
0
1
1
0
1
1
0
1
1
1
0
Writing Data
1
0
1
1
1
1
There are two types of writes used in the NCT75:
2
The NCT75 also features a SMBus/I C timeout function
2
Setting up the Address Pointer Register for a Register
Read
whereby the SMBus/I C interface times out after 22.5 ms of
no activity on the SDA line. After this time, the NCT75
resets the SDA line back to its idle state (high impedance)
and waits for the next start condition.
To read data from a particular register, the address pointer
register must hold the address of the register being read. To
configure the address pointer register a single write
operation (shown in Figure 5). It consists of the device
address followed by the address being written to the address
pointer register. This will then be followed by a read
operation.
The serial bus protocol operates as follows:
1. The master initiates data transfer by establishing
a start condition, defined as a high to low
transition on the serial data line SDA, while the
serial clock line SCL remains high. This indicates
that an address/data stream is going to follow. All
slave peripherals connected to the serial bus
respond to the start condition and shift in the next
eight bits, consisting of a 7-bit address (MSB first)
plus a read/write (R/W) bit, which deternimes the
direction of the data transfer i.e. whether data is
written to, or read from, the slave device. The
peripheral with the address corresponding to the
transmitted address responds by pulling the data
line low during the low period before the ninth
clock pulse, known as the acknowledge bit. All
other devices on the bus now remain idle while the
selected device waits for data to be read from or
written to it. If the R/W bit is a zero then the
Writing Data to a Register
Due to the different size registers used by the NCT75,
there are two types of write operations. One is for the 8 bit
wide configuration register and the other for the 16 bit wide
limit registers.
Figure 6 shows the sequence required to write to the
configuration register. It consists of the device address, the
data register being written to and the data being written the
selected register.
The two temperature limit registers (T
and T ) are
HYST
OS
16 bits wide and require two data bytes to be written to these
registers. This sequence is shown in Figure 7. It consists of
the device address, the data register being written to and the
two data byes being written to the selected register.
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8
NCT75
1
9
1
9
SCL
SDA
R/W
A6
A5
A4 A3 A2
FRAME 1
A1 A0
D7 D6 D5 D4 D3 D2 D1 D0
STOP BY
MASTER
ACK. BY
NCT75
ACK. BY
NCT75
START BY
MASTER
FRAME 2
SERIAL BUS ADDRESS BYTE
ADDRESS POINTER REGISTER BYTE
Figure 5. Writing to the Address Pointer Register
1
9
1
9
SCL
SDA
R/W
A6
A5
A4
A3
A2
A1
A0
D7
D6
D5
D4
D3
D2
D1
D0
ACK. BY
NCT75
ACK. BY
NCT75
START BY
MASTER
FRAME 2
FRAME 1
SERIAL BUS ADDRESS BYTE
ADDRESS POINTER REGISTER BYTE
1
9
SCL (CONTINUED)
D7
D6
D5
D4
D3
D2
D1
D0
ACK. BY
SDA (CONTINUED)
STOP BY
MASTER
NCT75
FRAME 3
DATA BYTE
Figure 6. Writing a Register Address to the Address Pointer Register, then
Writing a Single Byte of Data to the Configuration Register
1
9
1
9
SCL
SDA
R/W
A6 A5 A4 A3 A2
FRAME 1
A1 A0
D7 D6 D5 D4 D3 D2 D1 D0
ACK. BY
NCT75
ACK. BY
NCT75
START BY
MASTER
FRAME 2
ADDRESS POINTER REGISTER BYTE
SERIAL BUS ADDRESS BYTE
1
9
1
9
SCL
(CONTINUED)
SDA
(CONTINUED)
D15 D14 D13 D12 D11 D10 D9
D8
D7 D6 D5 D4 D3 D2 D1 D0
ACK. BY STOP BY
ACK. BY
NCT75
NCT75
MASTER
FRAME 4
DATA BYTE
FRAME 3
DATA BYTE
Figure 7. Writing to the Address Pointer Register Followed by
Two Bytes of Data to a 16 Bit Limit Register
1
9
1
9
SCL
SDA
A6 A5
A4 A3 A2
FRAME 1
A1 A0
D7 D6 D5 D4 D3 D2 D1 D0
R/W
ACK. BY
STOP BY
MASTER
NO ACK. BY
START BY
MASTER
NCT75
MASTER
DATA BYTE FROM REGISTER
FRAME 2
SERIAL BUS ADDRESS BYTE
Figure 8. Reading Data from the Configuration Register
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9
NCT75
1
9
1
9
SCL
SDA
A6
A5
A4
A3
A2
A1
A0
D15 D14 D13 D12 D11 D10 D9
D8
R/W
ACK. BY
MASTER
ACK. BY
NCT75
START BY
MASTER
FRAME 1
SERIAL BUS ADDRESS BYTE
FRAME 2
MSB DATA FROM TEMPERATURE
VALUE REGISTER
1
9
SCL (CONTINUED)
SDA (CONTINUED)
D7
D6
D5
D4
D3
D2
D1
D0
STOP BY
MASTER
NO ACK. BY
MASTER
FRAME 3
LSB DATA FROM TEMPERATURE
VALUE REGISTER
Figure 9. Reading Data from the Temperature Value Register
Reading Data
More information on comparator and interrupt modes
alsong with the SMBus alert mode are explained below.
Reading data from the NCT75 is done in two different
ways depending on the register being read. The
configuration register is only 8 bits wide so a single byte
read is used for this (shown in Figure 8). This consists of the
device address followed by the data from the register.
Reading the data in the temperature value register requires
a two byte read (shown in Figure 9). This consists of the
device address, followed by two bytes of data from the
temperature register (the first byte is the MSB). In both cases
the address pointer register of the register being read must
be written to prior to performing a read operation.
Comparator Mode
In Comparator Mode, the OS/ALERT pin becomes active
when the measured temperature equals or exceeds the limit
stored in the T setpoint register. The pin returns to its
OS
inactive status when the temperature drops below the T
setpoint register value.
HYST
NOTE: Shutdown mode does not reset the output state for
comparator mode.
Interrupt Mode
In the interrupt mode, the OS/ALERT pin becomes active
OS/ALERT Output Overtemperature Modes
when the temperature equals or exceeds the T limit for
The OS/ALERT output pin can operate in two different
modes – overtemperature mode and SMBus alert mode. The
pin defaults to overtemperature mode on power up. This
means that it becomes active when the measured
OS
a consecutive number of faults. It can be reset by performing
a read operation on any register in the NCT75. The output
can only become active again when the T limit has been
OS
equalled or exceeded.
temperature meets or exceeds the limit stored in the T
OS
Figure 10 shows how both the interrupt and comparator
modes operate in relation to the output pin (OS/ALERT). It
also shows the operation of the polarity bit in the
configuration register.
setpoint register. At this point it can deal with the event in
one of two ways which depends on the mode it is in. The two
overtemperature modes are: comparator mode and interrupt
mode. Comparator mode is the default mode on power up.
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10
NCT75
82C
81C
80C
79C
78C
77C
76C
75C
74C
73C
72C
T
OS
T
HYST
OS/ALERT PIN
(COMPARATOR MODE)
POLARITY = 0
OS/ALERT PIN
(INTERRUPT MODE)
POLARITY = 0
OS/ALERT PIN
(COMPARATOR MODE)
POLARITY = 1
OS/ALERT PIN
(INTERRUPT MODE)
POLARITY = 1
Figure 10. OS/ALERT Output Temperature Response Diagram
Table 15. ORDERING INFORMATION
†
Model Number*
NCT75DMR2G
Temperature Range
−55C to +125C
−55C to +125C
−55C to +125C
Temperature Accuracy
Package Description
8-lead Micro8t
8-lead SOIC
Package Option
1C
1C
1C
3,000 Tape & Reel
2,500 Tape & Reel
3,000 Tape & Reel
NCT75DR2G
NCT75MNR2G
8-lead DFN (2x2)
†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging
Specifications Brochure, BRD8011/D.
*The “G’’ suffix indicates Pb-Free package available.
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11
NCT75
PACKAGE DIMENSIONS
DFN8 2x2, 0.5P
CASE 506AA−01
ISSUE E
NOTES:
D
A
B
L
L
1. DIMENSIONING AND TOLERANCING PER
ASME Y14.5M, 1994 .
2. CONTROLLING DIMENSION: MILLIMETERS.
3. DIMENSION b APPLIES TO PLATED
TERMINAL AND IS MEASURED BETWEEN
0.15 AND 0.20 MM FROM TERMINAL TIP.
4. COPLANARITY APPLIES TO THE EXPOSED
PAD AS WELL AS THE TERMINALS.
L1
PIN ONE
DETAIL A
REFERENCE
E
OPTIONAL
CONSTRUCTIONS
MILLIMETERS
2X
0.10
C
DIM MIN
MAX
1.00
0.05
A
A1
A3
b
0.80
0.00
0.20 REF
0.20
2.00 BSC
EXPOSED Cu
MOLD CMPD
2X
0.10
C
TOP VIEW
0.30
1.30
D
D2
1.10
E
E2
e
K
L
L1
A
C
DETAIL B
0.10
0.08
C
C
DETAIL B
OPTIONAL
CONSTRUCTION
(A3)
A1
NOTE 4
SEATING
PLANE
SIDE VIEW
DETAIL A
RECOMMENDED
SOLDERING FOOTPRINT*
D2
8X
L
4
5
1
8X
0.50
1.30
PACKAGE
OUTLINE
E2
8
K
8X b
0.90
2.30
e/2
e
0.10 C A B
NOTE 3
C
0.05
1
BOTTOM VIEW
8X
0.30
0.50
PITCH
DIMENSIONS: MILLIMETERS
*For additional information on our Pb-Free strategy and soldering
details, please download the ON Semiconductor Soldering and
Mounting Techniques Reference Manual, SOLDERRM/D.
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12
NCT75
PACKAGE DIMENSIONS
Micro8t
CASE 846A−02
ISSUE H
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
D
3. DIMENSION A DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE
BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED
0.15 (0.006) PER SIDE.
4. DIMENSION B DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSION.
INTERLEAD FLASH OR PROTRUSION SHALL NOT EXCEED 0.25 (0.010) PER SIDE.
5. 846A-01 OBSOLETE, NEW STANDARD 846A-02.
H
E
E
MILLIMETERS
INCHES
NOM
−−
0.003
0.013
0.007
0.118
DIM
A
A1
b
c
D
MIN
−−
0.05
0.25
0.13
2.90
2.90
NOM
−−
MAX
MIN
−−
0.002
0.010
0.005
0.114
0.114
MAX
0.043
0.006
0.016
0.009
0.122
0.122
PIN 1 ID
1.10
0.15
0.40
0.23
3.10
3.10
e
0.08
b 8 PL
0.33
M
S
S
0.08 (0.003)
T B
A
0.18
3.00
E
3.00
0.118
e
L
0.65 BSC
0.55
4.90
0.026 BSC
0.021
0.193
0.40
4.75
0.70
5.05
0.016
0.187
0.028
0.199
SEATING
PLANE
H
−T−
E
A
0.038 (0.0015)
L
A1
c
SOLDERING FOOTPRINT*
1.04
0.38
8X
8X 0.041
0.015
3.20
4.24
5.28
0.126
0.167 0.208
0.65
6X0.0256
SCALE 8:1
mm
inches
ǒ
Ǔ
*For additional information on our Pb-Free strategy and soldering
details, please download the ON Semiconductor Soldering and
Mounting Techniques Reference Manual, SOLDERRM/D.
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13
NCT75
PACKAGE DIMENSIONS
SOIC−8 NB
CASE 751−07
ISSUE AK
NOTES:
1. DIMENSIONING AND TOLERANCING PER
ANSI Y14.5M, 1982.
−X−
A
2. CONTROLLING DIMENSION: MILLIMETER.
3. DIMENSION A AND B DO NOT INCLUDE
MOLD PROTRUSION.
4. MAXIMUM MOLD PROTRUSION 0.15 (0.006)
PER SIDE.
8
5
4
5. DIMENSION D DOES NOT INCLUDE DAMBAR
PROTRUSION. ALLOWABLE DAMBAR
PROTRUSION SHALL BE 0.127 (0.005) TOTAL
IN EXCESS OF THE D DIMENSION AT
MAXIMUM MATERIAL CONDITION.
6. 751−01 THRU 751−06 ARE OBSOLETE. NEW
STANDARD IS 751−07.
S
M
M
B
0.25 (0.010)
Y
1
K
−Y−
MILLIMETERS
DIM MIN MAX
INCHES
G
MIN
MAX
0.197
0.157
0.069
0.020
A
B
C
D
G
H
J
K
M
N
S
4.80
3.80
1.35
0.33
5.00 0.189
4.00 0.150
1.75 0.053
0.51 0.013
C
N X 45
_
SEATING
PLANE
1.27 BSC
0.050 BSC
−Z−
0.10
0.19
0.40
0
0.25 0.004
0.25 0.007
1.27 0.016
0.010
0.010
0.050
8
0.020
0.244
0.10 (0.004)
M
J
H
D
8
0
_
_
_
_
0.25
5.80
0.50 0.010
6.20 0.228
M
S
S
X
0.25 (0.010)
Z
Y
SOLDERING FOOTPRINT*
1.52
0.060
7.0
4.0
0.275
0.155
0.6
0.024
1.270
0.050
mm
inches
ǒ
Ǔ
SCALE 6:1
*For additional information on our Pb-Free strategy and soldering
details, please download the ON Semiconductor Soldering and
Mounting Techniques Reference Manual, SOLDERRM/D.
Micro8 is a trademark of International Rectifier.
ON Semiconductor and
are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC owns the rights to a number of patents, trademarks,
copyrights, trade secrets, and other intellectual property. A listing of SCILLC’s product/patent coverage may be accessed at www.onsemi.com/site/pdf/Patent−Marking.pdf. SCILLC
reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any
particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without
limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications
and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC
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NCT75/D
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