AD ADT7310TRZ-REEL 16-bit digital spi temperature sensor Datasheet

±0.5°C Accurate, 16-Bit
Digital SPI Temperature Sensor
ADT7310
Data Sheet
FEATURES
Thermal protection
Industrial process control
Power system monitors
Hand-held applications
High performance
Temperature accuracy
±0.5°C from −40°C to +105°C (2.7 V to 3.6 V)
±0.4°C from −40°C to +105°C (3.0 V)
16-bit temperature resolution: 0.0078°C
Fast first temperature conversion on power-up of 6 ms
Easy implementation
No temperature calibration/correction required by user
No linearity correction required
Low power
Power saving 1 sample per second (SPS) mode
700 µW typical at 3.3 V in normal mode
7 µW typical at 3.3 V in shutdown mode
Wide operating ranges
Temperature range: −55°C to +150°C
Voltage range: 2.7 V to 5.5 V
Programmable interrupts
Critical overtemperature interrupt
Overtemperature/undertemperature interrupt
SPI-compatible interface
8-lead narrow SOIC RoHS-compliant package
GENERAL DESCRIPTION
The ADT7310 is a high accuracy digital temperature sensor
in a narrow SOIC package. It contains a band gap temperature
reference and a 13-bit ADC to monitor and digitize the
temperature to a 0.0625°C resolution. The ADC resolution,
by default, is set to 13 bits (0.0625 °C). This can be changed
to 16 bits (0.0078 °C) by setting Bit 7 in the configuration
register (Register Address 0x01).
The ADT7310 is guaranteed to operate over supply voltages from
2.7 V to 5.5 V. Operating at 3.3 V, the average supply current is
typically 210 μA. The ADT7310 has a shutdown mode that
powers down the device and offers a shutdown current of
typically 2 μA. The ADT7310 is rated for operation over the
−55°C to +150°C temperature range.
The CT pin is an open-drain output that becomes active when
the temperature exceeds a programmable critical temperature
limit. The default critical temperature limit is 147°C. The INT
pin is also an open-drain output that becomes active when the
temperature exceeds a programmable limit. The INT and CT
pins can operate in either comparator or interrupt mode.
APPLICATIONS
Medical equipment
Environmental control systems
Computer thermal monitoring
FUNCTIONAL BLOCK DIAGRAM
ADT7310
SPI INTERFACE
DOUT 2
DIN 3
CS 4
INTERNAL
REFERENCE
INTERNAL
OSCILLATOR
6
CT
5
INT
7
GND
8
VDD
TCRIT
TEMPERATURE
VALUE
REGISTER
CONFIGURATION
AND STATUS
REGISTERS
THYST
REGISTER
TCRIT
REGISTER
THIGH
REGISTER
TLOW
REGISTER
TEMPERATURE
SENSOR
Σ-Δ
MODULATOR
THIGH
FILTER
LOGIC
TLOW
07789-001
SCLK 1
Figure 1.
Rev. A
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ADT7310* PRODUCT PAGE QUICK LINKS
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EVALUATION KITS
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DESIGN RESOURCES
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DOCUMENTATION
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Application Notes
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• Symbols and Footprints
Data Sheet
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Sensor Data Sheet
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User Guides
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Sensors
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ADT7310
Data Sheet
TABLE OF CONTENTS
Features .............................................................................................. 1
Status Register ............................................................................. 14
Applications ....................................................................................... 1
Configuration Register .............................................................. 15
General Description ......................................................................... 1
Temperature Value Register ...................................................... 16
Functional Block Diagram .............................................................. 1
ID Register................................................................................... 16
Revision History ............................................................................... 2
TCRIT Setpoint Register ............................................................... 16
Specifications..................................................................................... 3
THYST Setpoint Register............................................................... 17
SPI Timing Specifications ........................................................... 4
THIGH Setpoint Register .............................................................. 17
Absolute Maximum Ratings ............................................................ 5
TLOW Setpoint Register ............................................................... 17
ESD Caution .................................................................................. 5
Serial Interface ................................................................................ 18
Pin Configuration and Function Descriptions ............................. 6
SPI Command Byte .................................................................... 18
Typical Performance Characteristics ............................................. 7
Writing Data ............................................................................... 19
Theory of Operation ........................................................................ 9
Reading Data ............................................................................... 20
Circuit Information ...................................................................... 9
Interfacing to DSPs or Microcontrollers ................................. 20
Converter Details.......................................................................... 9
Serial Interface Reset.................................................................. 20
Temperature Measurement ......................................................... 9
INT and CT Outputs...................................................................... 21
One-Shot Mode .......................................................................... 10
Undertemperature and Overtemperature Detection ............ 21
1 SPS Mode .................................................................................. 10
Applications Information .............................................................. 23
Continuous Read Mode ............................................................. 12
Thermal Response Time ........................................................... 23
Shutdown ..................................................................................... 12
Supply Decoupling ..................................................................... 23
Fault Queue ................................................................................. 12
Temperature Monitoring ........................................................... 23
Temperature Data Format ......................................................... 13
Outline Dimensions ....................................................................... 24
Temperature Conversion Formulas ......................................... 13
Ordering Guide .......................................................................... 24
Registers ........................................................................................... 14
REVISION HISTORY
12/11—Rev. 0 to Rev. A
Changes to Features Section............................................................ 1
Changes to Table 1 ............................................................................ 3
Changes to Figure 6 and Figure 9 ................................................... 7
Changes to Figure 11 ........................................................................ 8
Changes to One-Shot Mode Section and 1 SPS Mode
Section .............................................................................................. 10
Changes to Shutdown Section and Figure 16 ............................. 12
Changes to Table 7.......................................................................... 14
Changes to Table 8.......................................................................... 15
Changes to Table 9.......................................................................... 16
Changes to Table 12, Table 13, and Table 14............................... 17
Changes to Ordering Guide .......................................................... 24
4/09—Revision 0: Initial Version
Rev. A | Page 2 of 24
Data Sheet
ADT7310
SPECIFICATIONS
TA = −55°C to +150°C; VDD = 2.7 V to 5.5 V; unless otherwise noted.
Table 1.
Parameter
TEMPERATURE SENSOR AND ADC
Accuracy 1
Min
ADC Resolution
Temperature Resolution
13-Bit
16-Bit
Temperature Conversion Time
Fast Temperature Conversion Time
1 SPS Conversion Time
Temperature Hysteresis
Repeatability 3
DC PSRR
DIGITAL OUTPUTS (OPEN DRAIN)
High Output Leakage Current, IOH
Output High Current
Output Low Voltage, VOL
Output High Voltage, VOH
Output Capacitance, COUT
DIGITAL INPUTS
Input Current
Input Low Voltage, VIL
Input High Voltage, VIH
Pin Capacitance
DIGITAL OUTPUT (DOUT)
Output High Voltage, VOH
Output Low Voltage, VOL
Output Capacitance, COUT
POWER REQUIREMENTS
Supply Voltage
Supply Current
At 3.3 V
At 5.5 V
1 SPS Current
At 3.3V
At 5.5V
Shutdown Current
At 3.3 V
At 5.5 V
Power Dissipation Normal Mode
Power Dissipation 1 SPS
1
2
3
Typ
Max
Unit
Test Conditions/Comments
−0.05
±0.4 2
±0.44
±0.5
±0.5
±0.7
±0.8
±1.0
13
°C
°C
°C
°C
°C
°C
°C
Bits
16
Bits
TA = −40°C to +105°C, VDD = 3.0 V
TA = −40°C to +105°C, VDD = 2.7 V to 3.3 V
TA = −55°C to +125°C, VDD = 3.0 V
TA = −40°C to +105°C, VDD = 2.7 V to 3.6 V
TA = −55°C to +150°C, VDD = 2.7 V to 3.6 V
TA = −40°C to +105°C, VDD = 4.5 V to 5.5 V
TA = −55°C to +150°C, VDD = 2.7 V to 5.5 V
Twos complement temperature value of sign bit plus 12 ADC bits
(power-up default resolution)
Twos complement temperature value of sign bit plus 15 ADC bits
(Bit 7 = 1 in the configuration register)
0.0625
0.0078
240
6
60
±0.002
±0.015
0.1
°C
°C
ms
ms
ms
°C
°C
°C/V
13-bit resolution (sign + 12-bit)
16-bit resolution (sign + 15-bit)
Continuous conversion and one-shot conversion mode
First conversion on power-up only
Conversion time for 1 SPS mode
Temperature cycle = 25°C to 125°C, and back to 25°C
TA = 25°C
TA = 25°C
5
1
0.4
µA
mA
V
V
pF
CT and INT pins pulled up to 5.5 V
VOH = 5 .5V
IOL = 2 mA @ 5.5 V, IOL = 1 mA @ 3.3 V
±1
0.4
VIN = 0 V to VDD
10
µA
V
V
pF
0.4
50
V
V
pF
ISOURCE = ISINK = 200 µA
IOL = 200 µA
5.5
V
250
300
µA
µA
Peak current while converting, SPI interface inactive
Peak current while converting, SPI interface inactive
µA
µA
VDD = 3.3 V, 1 SPS mode, TA = 25°C
VDD = 5.5 V, 1 SPS mode, TA = 25°C
µA
µA
µW
µW
Supply current in shutdown mode
Supply current in shutdown mode
VDD = 3.3 V, normal mode at 25°C
Power dissipated for VDD = 3.3 V, TA = 25°C
0.1
0.7 × VDD
3
0.7 × VDD
5
VOH − 0.3
2.7
210
250
46
65
2.0
5.2
700
150
15
25
Accuracy includes lifetime drift.
The equivalent 3 σ limits are ±0.33°C. This 3 σ specification is provided to enable comparison with other vendors who use these limits.
Based on a floating average of 10 readings.
Rev. A | Page 3 of 24
ADT7310
Data Sheet
SPI TIMING SPECIFICATIONS
TA = −55°C to +150°C, VDD = 2.7 V to 5.5 V, unless otherwise noted. All input signals are specified with rise time (tR) = fall time (tF) = 5 ns
(10% to 90% of VDD) and timed from a voltage level of 1.6 V.
Table 2.
Parameter1, 2
Limit at TMIN, TMAX (B Version)
Unit
Conditions/Comments
t1
t2
t3
t4
t5
t6
0
100
100
30
25
0
60
80
10
80
0
0
60
80
10
ns min
ns min
ns min
ns min
ns min
ns min
ns max
ns max
ns min
ns max
ns min
ns min
ns max
ns max
ns min
CS falling edge to SCLK active edge setup time3
SCLK high pulse width
SCLK low pulse width
Data valid to SCLK edge setup time
Data valid to SCLK edge hold time
SCLK active edge to data valid delay3
VDD = 4.5 V to 5.5 V
VDD = 2.7 V to 3.6 V
Bus relinquish time after CS inactive edge
t74
t8
t9
t10
CS rising edge to SCLK edge hold time
CS falling edge to DOUT active time
VDD = 4.5 V to 5.5 V
VDD = 2.7 V to 3.6 V
SCLK inactive edge to DOUT high
1
Sample tested during initial release to ensure compliance. All input signals are specified with tR = tF = 5 ns (10% to 90% of VDD) and timed from a voltage level of 1.6 V.
See Figure 2.
SCLK active edge is falling edge of SCLK.
4
This means that the times quoted in the timing characteristics are the true bus relinquish times of the part and, as such, are independent of external bus loading
capacitances.
2
3
CS
t2
1
SCLK
t4
t8
t3
2
7
3
8
2
7
8
t5
MSB
DIN
1
LSB
t6
t9
DOUT
Figure 2. Detailed SPI Timing Diagram
ISINK (1.6mA WITH VDD = 5V,
100µA WITH VDD = 3V)
1.6V
Figure 3. Load Circuit for Timing Characterization
Rev. A | Page 4 of 24
07789-004
10pF
ISOURCE (200µA WITH VDD = 5V,
100µA WITH VDD = 3V)
t7
LSB
MSB
TO
OUTPUT
PIN
t10
07789-002
t1
Data Sheet
ADT7310
ABSOLUTE MAXIMUM RATINGS
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
Table 3.
Rating
–0.3 V to +7 V
–0.3 V to VDD + 0.3 V
–0.3 V to VDD + 0.3 V
–0.3 V to VDD + 0.3 V
–0.3 V to VDD + 0.3 V
–0.3 V to VDD + 0.3 V
2.0 kV
–55°C to +150°C
–65°C to +160°C
150°C
1.2
WMAX = (TJMAX − TA2)/θJA
121°C/W
56°C/W
220°C
260°C (0°C)
1.0
0.8
0.6
0.4
0.2
MAX PD = 3.4mW AT 150°C
–55
–50
–40
–30
–20
–10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
0
20 sec to 40 sec
3°C/sec maximum
–6°C/sec maximum
8 minutes maximum
TEMPERATURE (°C)
Figure 4. SOIC_N Maximum Power Dissipation vs. Temperature
ESD CAUTION
Values relate to package being used on a standard 2-layer PCB. This gives a
worst-case θJA and θJC. See Figure 4 for a plot of maximum power dissipation
vs. ambient temperature (TA).
2
TA = ambient temperature.
3
Junction-to-case resistance is applicable to components featuring a
preferential flow direction, for example, components mounted on a heat
sink. Junction-to-ambient is more useful for air-cooled, PCB-mounted
components.
1
Rev. A | Page 5 of 24
07789-003
MAXIMUM POWER DISSIPATION (W)
Parameter
VDD to GND
DIN Input Voltage to GND
DOUT Voltage to GND
SCLK Input Voltage to GND
CS Input Voltage to GND
CT and INT Output Voltage to GND
ESD Rating (Human Body Model)
Operating Temperature Range
Storage Temperature Range
Maximum Junction Temperature, TJMAX
8-Lead SOIC-N (R-8)
Power Dissipation1
Thermal Impedance3
θJA, Junction-to-Ambient (Still Air)
θJC, Junction-to-Case
IR Reflow Soldering
Peak Temperature (RoHSCompliant Package)
Time at Peak Temperature
Ramp-Up Rate
Ramp-Down Rate
Time from 25°C to Peak Temperature
ADT7310
Data Sheet
SCLK 1
DOUT 2
DIN 3
ADT7310
TOP VIEW
CS 4 (Not to Scale)
8
VDD
7
GND
6
CT
5
INT
07789-005
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
Figure 5. Pin Configuration
Table 4. Pin Function Descriptions
Pin No.
1
2
3
Mnemonic
SCLK
DOUT
DIN
4
5
CS
INT
6
CT
7
8
GND
VDD
Description
Serial Clock Input. The serial clock is used to clock in and clock out data to and from any register of the ADT7310.
Serial Data Output. Data is clocked out on the SCLK falling edge and is valid on the SCLK rising edge.
Serial Data Input. Serial data to be loaded to the part’s control registers is provided on this input. Data is clocked
into the registers on the rising edge of SCLK.
Chip Select Input. The device is selected when this input is low. The device is disabled when this pin is high.
Overtemperature and Undertemperature Indicator. Logic output. Power-up default setting is as an active low
comparator interrupt. Open-drain configuration. A pull-up resistor is required, typically 10 kΩ.
Critical Overtemperature Indicator. Logic output. Power-up default polarity is active low. Open-drain
configuration. A pull-up resistor is required, typically 10 kΩ.
Analog and Digital Ground.
Positive Supply Voltage (2.7 V to 5.5 V). The supply should be decoupled with a 0.1 µF ceramic capacitor to
ground.
Rev. A | Page 6 of 24
Data Sheet
ADT7310
TYPICAL PERFORMANCE CHARACTERISTICS
0.30
1.0
5.5V CONTINUOUS
CONVERSION
0.25
0.6
3.0V CONTINUOUS
CONVERSION
MAX ACCURACY LIMITS
0.4
0.20
0.2
IDD (mA)
0
–0.2
0.15
0.10
–0.4
5.5V 1SPS
MAX ACCURACY LIMITS
–0.6
0.05
3.0V 1SPS
–0.8
–40
–20
0
20
40
60
80
100
120
140
160
TEMPERATURE (°C)
0
–100
07789-006
–1.0
–60
–50
0
50
100
150
200
TEMPERATURE (°C)
07789-007
TEMPERATURE ERROR (°C)
0.8
Figure 8. Operating Supply Current vs. Temperature
Figure 6. Temperature Accuracy at 3 V
30
1.0
0.8
25
SHUTDOWN IDD (µA)
0.4
0.2
0
–0.2
–0.4
15
10
5.5V
4.5V
3.3V
3.0V
2.7V
3.6V
–40
–20
0
20
40
60
80
100
120
TEMPERATURE (°C)
140
160
0
–100
–50
0
50
100
150
TEMPERATURE (°C)
Figure 7. Temperature Accuracy at 5 V
Figure 9. Shutdown Current vs. Temperature
Rev. A | Page 7 of 24
200
07789-025
5
MAX ACCURACY LIMITS
–0.8
–1.0
–60
20
5.0V
–0.6
07789-024
TEMPERATURE ERROR (°C)
MAX ACCURACY LIMITS
0.6
ADT7310
Data Sheet
0.30
160
140
IDD CONTINUOUS CONVERSION
0.25
TEMPERATURE (°C)
120
IDD (mA)
0.20
0.15
0.10
100
80
60
40
IDD 1SPS
0.05
3.0
3.5
4.0
4.5
5.0
5.5
6.0
SUPPLY VOLTAGE (V)
0
07789-008
0
2.5
0
8
7
5
4
3
2
1
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
6.0
07789-009
SHUTDOWN IDD (µA)
6
3.0
10
15
20
25
30
TIME (Seconds)
Figure 10. Average Operating Supply Current vs. Supply Voltage at 25°C
0
2.5
5
Figure 11. Shutdown Current vs. Supply Voltage at 25°C
Rev. A | Page 8 of 24
Figure 12. Response to Thermal Shock
35
40
07789-011
20
Data Sheet
ADT7310
THEORY OF OPERATION
CIRCUIT INFORMATION
Σ-∆ MODULATOR
INTEGRATOR
COMPARATOR
The ADT7310 is a 13-bit digital temperature sensor that is
extendable to 16-bits for greater resolution. An on-board
temperature sensor generates a voltage proportional to absolute
temperature, which is compared to an internal voltage reference
and input to a precision digital modulator.
VOLTAGE REF
AND VPTAT
1-BIT
DAC
The sensor output is digitized by a sigma-delta (Σ-Δ)
modulator, also known as the charge balance type analog-todigital converter. This type of converter utilizes time-domain
oversampling and a high accuracy comparator to deliver
16-bits of resolution in an extremely compact circuit.
Configuration register functions consist of






Switching between 13-bit and 16-bit resolution
Switching between normal operation and full power-down
Switching between comparator and interrupt event modes
on the INT and CT pins
Setting the active polarity of the CT and INT pins
Setting the number of faults that activate CT and INT
Enabling the standard one-shot mode and 1 SPS mode
CONVERTER DETAILS
The Σ-Δ modulator consists of an input sampler, a summing
network, an integrator, a comparator, and a 1-bit DAC. This
architecture creates a negative feedback loop and minimizes the
integrator output by changing the duty cycle of the comparator
output in response to input voltage changes. The comparator
samples the output of the integrator at a much higher rate than
the input sampling frequency. This oversampling spreads the
quantization noise over a much wider band than that of the
input signal, improving overall noise performance and
increasing accuracy.
The modulated output of the comparator is encoded using a
circuit technique that results in SPI temperature data.
1-BIT
CLOCK
GENERATOR
LPF DIGITAL
FILTER
13-BIT
TEMPERATURE
VALUE
REGISTER
07789-012
The on-board temperature sensor has excellent accuracy and
linearity over the entire rated temperature range without
needing correction or calibration by the user.
Figure 13. Σ-∆ Modulator
TEMPERATURE MEASUREMENT
In normal mode, the ADT7310 runs an automatic conversion
sequence. During this automatic conversion sequence, a conversion takes 240 ms to complete and the ADT7310 is continuously
converting. This means that as soon as one temperature conversion is completed, another temperature conversion begins. Each
temperature conversion result is stored in the temperature value
register and is available through the SPI interface. In continuous
conversion mode, the read operation provides the most recent
converted result.
On power-up, the first conversion is a fast conversion, taking
typically 6 ms. If the temperature exceeds 147°C, the CT pin
asserts low. If the temperature exceeds 64°C, the INT pin asserts
low. Fast conversion temperature accuracy is typically within ±5°C.
The conversion clock for the part is generated internally.
No external clock is required except when reading from and
writing to the serial port.
The measured temperature value is compared with a critical
temperature limit (stored in the 16-bit TCRIT setpoint read/write
register), a high temperature limit (stored in the 16-bit THIGH
setpoint read/write register), and a low temperature limit (stored
in the 16-bit TLOW setpoint read/write register). If the measured
value exceeds these limits, the INT pin is activated; and if it
exceeds the TCRIT limit, the CT pin is activated. The INT and CT
pins are programmable for polarity via the configuration register,
and the INT and CT pins are also programmable for interrupt
mode via the configuration register.
Rev. A | Page 9 of 24
ADT7310
Data Sheet
CS
0x08
DIN
0x20
WAIT 240ms MINIMUM
FOR CONVERSION TO FINISH
DATA
07789-026
DOUT
SCLK
Figure 14. Typical SPI One-Shot Write to Configuration Register Followed by a Read from the Temperature Value Register
ONE-SHOT MODE
1 SPS MODE
When one-shot mode is enabled, the ADT7310 immediately
completes a conversion and then goes into shutdown mode. The
one-shot mode is useful when one of the circuit design priorities is
to reduce power consumption.
In this mode, the part performs one measurement per second.
A conversion takes only 60 ms, and it remains in the idle state
for the remaining 940 ms period. This mode is enabled by
writing 1 to Bit 6 and 0 to Bit 5 of the configuration register
(Register Address 0x01).
To enable one-shot mode, set Bits[6:5] of the configuration
register (Register Address 0x01) to 01.
After writing to the operation mode bits, wait at least 240 ms
before reading back the temperature from the temperature value
register. This delay ensures that the ADT7310 has adequate time
to power up and complete a conversion.
To obtain an updated temperature conversion, reset Bits[6:5] of the
configuration register (Register Address 0x01) to 01.
Rev. A | Page 10 of 24
Data Sheet
ADT7310
For the CT pin in the comparator mode, if the temperature
drops below the TCRIT – THYST value, a write to the one-shot
bits (Bit 5 and Bit 6 of the configuration register, Register
Address 0x01) resets the CT pin; see Figure 15.
CT and INT Operation in One-Shot Mode
See Figure 15 for more information on one-shot CT pin
operation for TCRIT overtemperature events when one of the
limits is exceeded. Note that in interrupt mode, a read from
any register resets the INT and CT pins.
For the INT pin in the comparator mode, if the temperature
drops below the THIGH – THYST value or goes above the TLOW +
THYST value, a write to the one-shot bits (Bit 5 and Bit 6 of the
configuration register, Register Address 0x01) resets the INT pin.
Note that when using one-shot mode, ensure that the refresh
rate is appropriate to the application being used.
TEMPERATURE
149°C
148°C
TCRIT
147°C
146°C
145°C
144°C
143°C
TCRIT – THYST
142°C
141°C
140°C
CT PIN
POLARITY = ACTIVE LOW
CT PIN
POLARITY = ACTIVE HIGH
TIME
WRITE TO
BIT 5 AND BIT 6 OF
CONFIGURATION
REGISTER.*
WRITE TO
BIT 5 AND BIT 6 OF
CONFIGURATION
REGISTER.*
*THERE IS A 240ms DELAY BETWEEN WRITING TO THE CONFIGURATION REGISTER TO START
A STANDARD ONE-SHOT CONVERSION AND THE CT PIN GOING ACTIVE. THIS IS DUE TO THE
CONVERSION TIME. THE DELAY IS 60ms IN THE CASE OF A ONE-SHOT CONVERSION.
Figure 15. One-Shot CT Pin
Rev. A | Page 11 of 24
07789-013
WRITE TO
BIT 5 AND BIT 6 OF
CONFIGURATION
REGISTER.*
ADT7310
Data Sheet
CONTINUOUS READ MODE
SHUTDOWN
When the command byte = 01010100 (0x54), the contents of
the temperature value register can be read out without requiring
repeated writes to the communications register. By sending 16
SCLK clocks to the ADT7310, the contents of the temperature
value register are output onto the DOUT pin.
The ADT7310 can be placed in shutdown mode by writing 1
to Bit 6 and 1 to Bit 5 of the configuration register (Register
Address 0x01). The ADT7310 can be taken out of shutdown
mode by writing 0 to Bit 6 and 0 to Bit 5 of the configuration
register (Register Address 0x01). The ADT7310 typically takes
1 ms (with a 0.1 µF decoupling capacitor) to come out of shutdown mode. The conversion result from the last conversion
prior to shutdown can still be read from the ADT7310 even
when it is in shutdown mode. When the part is taken out of
shutdown mode, the internal clock is started and a conversion
is initiated.
To exit the continuous read mode, the Command Byte
01010000 (0x50) must be written to the ADT7310.
While in continuous read mode, the part monitors activity on
the DIN line so that it can receive the instruction to exit the
continuous read mode. Additionally, a reset occurs if 32
consecutive 1s are seen on the DIN pin. Therefore, hold DIN
low in continuous read mode until an instruction is to be
written to the device.
In continuous read mode, the temperature value register cannot
be read when a conversion is taking place. If an attempt is made
to read the temperature value register while a conversion is
taking place, then all 0s are read. This is because the continuous
read mode blocks read access to temperature value register
during a conversion.
FAULT QUEUE
Bit 0 and Bit 1 of the configuration register (Register Address
0x01) are used to set up a fault queue. Up to four faults are
provided to prevent false tripping of the INT and CT pins
when the ADT7310 is used in a noisy temperature environment. The number of faults set in the queue must occur
consecutively to set the INT and CT outputs. For example,
if the number of faults set in the queue is four, then four
consecutive temperature conversions must occur, with each
result exceeding a temperature limit in any of the limit registers,
before the INT and CT pins are activated. If two consecutive
temperature conversions exceed a temperature limit and the
third conversion does not, the fault count is reset to zero.
CS
DOUT
0x54
TEMPERATURE
VALUE
TEMPERATURE
VALUE
TEMPERATURE
VALUE
07789-027
DIN
SCLK
Figure 16. Continuous Read Mode
Rev. A | Page 12 of 24
Data Sheet
ADT7310
TEMPERATURE DATA FORMAT
TEMPERATURE CONVERSION FORMULAS
One LSB of the ADC corresponds to 0.0625°C in 13-bit mode.
The ADC can theoretically measure a temperature range of
255°C, but the ADT7310 is guaranteed to measure a low value
temperature limit of −55°C to a high value temperature limit
of +150°C. The temperature measurement result is stored in
the 16-bit temperature value register and is compared with the
high temperature limits stored in the TCRIT setpoint register and
the THIGH setpoint register. It is also compared with the low
temperature limit stored in the TLOW setpoint register.
16-Bit Temperature Data Format
Temperature data in the temperature value register, the TCRIT
setpoint register, the THIGH setpoint register, and the TLOW
setpoint register are represented by a 13-bit twos complement
word. The MSB is the temperature sign bit. The three LSBs,
Bit 0 to Bit 2, on power-up, are not part of the temperature
conversion result and are flag bits for TCRIT, THIGH, and TLOW.
Table 5 shows the 13-bit temperature data format without
Bit 0 to Bit 2.
The number of bits in the temperature data-word can be
extended to 16 bits, twos complement, by setting Bit 7 to 1
in the configuration register (Register Address 0x01). When
using a 16-bit temperature data value, Bit 0 to Bit 2 are not
used as flag bits and are instead the LSB bits of the temperature
value. The power-on default setting has a 13-bit temperature
data value.
Reading back the temperature from the temperature value register
requires a 2-byte read. Designers that use a 9-bit temperature
data format can still use the ADT7310 by ignoring the last four
LSBs of the 13-bit temperature value. These four LSBs are Bit 3
to Bit 6 in Table 5.
Positive Temperature = ADC Code(dec)/128
Negative Temperature = (ADC Code(dec) – 65,536)/128
where ADC Code uses all 16 bits of the data byte, including the
sign bit.
Negative Temperature = (ADC Code(dec) – 32,768)/128
where the MSB is removed from the ADC code.
13-Bit Temperature Data Format
Positive Temperature = ADC Code(dec)/16
Negative Temperature = (ADC Code(dec) − 8192)/16
where ADC Code uses all 13 bits of the data byte, including the
sign bit.
Negative Temperature = (ADC Code(dec) – 4096)/16
where the MSB is removed from the ADC code.
10-Bit Temperature Data Format
Positive Temperature = ADC Code(dec)/2
Negative Temperature = (ADC Code(dec) – 1024)/2
where ADC Code uses all 10 bits of the data byte, including the
sign bit.
Negative Temperature = (ADC Code(dec) – 512)/2
where the MSB is removed from the ADC code.
9-Bit Temperature Data Format
Positive Temperature = ADC Code(dec)
Negative Temperature = ADC Code(dec) – 512
Table 5. 13-Bit Temperature Data Format
Temperature
−55°C
−50°C
−25°C
−0.0625°C
0°C
+0.0625°C
+25°C
+50°C
+125°C
+150°C
Digital Output
(Binary) Bits[15:3]
1 1100 1001 0000
1 1100 1110 0000
1 1110 0111 0000
1 1111 1111 1111
0 0000 0000 0000
0 0000 0000 0001
0 0001 1001 0000
0 0011 0010 0000
0 0111 1101 0000
0 1001 0110 0000
Digital
Output (Hex)
0x1C90
0x1CE0
0x1E70
0x1FFF
0x000
0x001
0x190
0x320
0x7D0
0x960
where ADC Code uses all nine bits of the data byte, including
the sign bit.
Negative Temperature = ADC Code(dec) – 256
where the MSB is removed from the ADC code.
Rev. A | Page 13 of 24
ADT7310
Data Sheet
REGISTERS
The ADT7310 contains eight registers:
STATUS REGISTER
•
•
•
•
This 8-bit read-only register (Register Address 0x00) reflects the
status of the overtemperature and undertemperature interrupts
that can cause the CT and INT pins to go active. It also reflects the
status of a temperature conversion operation. The interrupt flags
in this register are reset by a read operation to the status register
and/or when the temperature value returns within the temperature limits including hysteresis. The RDY bit is reset after a read
from the temperature value register. In one-shot and 1 SPS
modes, the RDY bit is reset after a write to the one-shot bits.
A status register
A configuration register
Five temperature registers
An ID register
The status register, temperature value register, and the ID
register are read-only.
Table 6. ADT7310 Registers
Register
Address
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
Power-On
Default
0x80
0x00
0x0000
0xCX
0x4980 (147°C)
0x05 (5°C)
0x2000 (64°C)
0x0500 (10°C)
Description
Status
Configuration
Temperature value
ID
TCRIT setpoint
THYST setpoint
THIGH setpoint
TLOW setpoint
Table 7. Status Register (Register Address 0x00)
Bit
[3:0]
4
Default
Value
0000
0
Type
R
R
Name
Unused
TLOW
5
0
R
THIGH
6
0
R
TCRIT
7
1
R
RDY
Description
Reads back 0.
This bit is set to 1 when the temperature goes below the TLOW temperature limit. The bit clears to 0
when the status register is read and/or when the temperature measured goes back above the limit
set in the TLOW + THYST setpoint registers.
This bit is set to 1 when the temperature goes above the THIGH temperature limit. The bit clears to 0
when the status register is read and/or when the temperature measured goes back below the limit
set in the THIGH − THYST setpoint registers.
This bit is set to 1 when the temperature goes above the TCRIT temperature limit. This bit clears to 0
when the status register is read and/or when the temperature measured goes back below the limit
set in the TCRIT − THYST setpoint registers.
This bit goes low when the temperature conversion result is written into the temperature value
register. It is reset to 1 when the temperature value register is read. In one-shot and 1 SPS modes,
this bit is reset after a write to the one-shot bits.
Rev. A | Page 14 of 24
Data Sheet
ADT7310
CONFIGURATION REGISTER
This 8-bit read/write register stores various configuration modes
for the ADT7310, including shutdown, overtemperature and
undertemperature interrupts, one-shot, continuous conversion,
interrupt pins polarity, and overtemperature fault queues.
Table 8. Configuration Register (Register Address 0x01)
Bit
[1:0]
Default
Value
00
Type
R/W
Name
Fault queue
2
0
R/W
CT pin polarity
3
0
R/W
INT pin polarity
4
0
R/W
INT/CT mode
[6:5]
00
R/W
Operation mode
7
0
R/W
Resolution
Description
These two bits set the number of undertemperature/overtemperature faults that can
occur before setting the INT and CT pins. This helps to avoid false triggering due to
temperature noise.
00 = 1 fault (default).
01 = 2 faults.
10 = 3 faults.
11 = 4 faults.
This bit selects the output polarity of the CT pin.
0 = active low.
1 = active high.
This bit selects the output polarity of the INT pin.
0 = active low.
1 = active high.
This bit selects between comparator mode and interrupt mode.
0 = interrupt mode.
1 = comparator mode.
These two bits set the operational mode for the ADT7310.
00 = continuous conversion (default). When one conversion is finished, the ADT7310
starts another.
01 = one shot. Conversion time is typically 240 ms.
10 = 1 SPS mode. Conversion time is typically 60 ms. This operational mode reduces the
average current consumption.
11 = shutdown. All circuitry except interface circuitry is powered down.
This bit sets up the resolution of the ADC when converting.
0 = 13-bit resolution. Sign bit + 12 bits gives a temperature resolution of 0.0625°C.
1 = 16-bit resolution. Sign bit + 15 bits gives a temperature resolution of 0.0078125°C.
Rev. A | Page 15 of 24
ADT7310
Data Sheet
TEMPERATURE VALUE REGISTER
ID REGISTER
The temperature value register stores the temperature measured
by the internal temperature sensor. The temperature is stored as
a 16-bit twos complement format. The temperature is read back
from the temperature value register (Register Address 0x02) as a
16-bit value.
This 8-bit read-only register stores the manufacturer ID in Bit 7
to Bit 3 and the silicon revision in Bit 2 to Bit 0.
Bit 2, Bit 1, and Bit 0 are event alarm flags for TCRIT, THIGH, and
TLOW. When the ADC is configured to convert the temperature
to a 16-bit digital value, Bit 2, Bit 1, and Bit 0 are no longer used
as flag bits and are, instead, used as the LSB bits for the extended
digital value.
TCRIT SETPOINT REGISTER
The 16-bit TCRIT setpoint register (Register Address 0x04)
stores the critical overtemperature limit value. A critical
overtemperature event occurs when the temperature value
stored in the temperature value register exceeds the value
stored in this register. The CT pin is activated if a critical
overtemperature event occurs. The temperature is stored in
twos complement format with the MSB being the temperature
sign bit.
The default setting for the TCRIT setpoint is 147°C.
Table 9. Temperature Value Register (Register Address 0x02)
Bit
0
Default Value
0
Type
R
Name
TLOW flag/LSB0
1
0
R
THIGH flag/LSB1
2
0
R
TCRIT flag/LSB2
[7:3]
[14:8]
15
00000
0000000
0
R
R
R
Temp
Temp
Sign
Description
Flags a TLOW event if the configuration register, Register Address 0x01[7] = 0
(13-bit resolution). When the temperature value is below TLOW,, this bit it set to 1.
Contains the Least Significant Bit 0 of the 15-bit temperature value if the
configuration register, Register Address 0x01[7] = 1 (16-bit resolution).
Flags a THIGH event if the configuration register, Register Address 0x01[7] = 0
(13-bit resolution). When the temperature value is above THIGH, this bit it set to 1.
Contains the Least Significant Bit 1 of the 15-bit temperature value if the
configuration register, Register Address 0x01[7] = 1 (16-bit resolution).
Flags a TCRIT event if the configuration register, Register Address 0x01[7] = 0
(13-bit resolution). When the temperature value exceeds TCRIT, this bit it set to 1.
Contains the Least Significant Bit 2 of the 15-bit temperature value if the
configuration register, Register Address 0x01[7] = 1 (16-bit resolution).
Temperature value in twos complement format.
Temperature value in twos complement format.
Sign bit, indicates if the temperature value is negative or positive.
Table 10. ID Register (Register Address 0x03)
Bit
[2:0]
[7:3]
Default Value
XXX
11000
Type
R
R
Name
Revision ID
Manufacture ID
Description
Contains the silicon revision identification number.
Contains the manufacturer identification number.
Table 11. TCRIT Setpoint Register (Register Address 0x04)
Bit
Default Value
Type
Name
Description
[15:0]
0x4980
R/W
TCRIT
16-bit critical overtemperature limit, stored in twos complement format.
Rev. A | Page 16 of 24
Data Sheet
ADT7310
THYST SETPOINT REGISTER
The THYST setpoint 8-bit register (Register Address 0x05) stores
the temperature hysteresis value for the THIGH, TLOW, and TCRIT
temperature limits. The temperature hysteresis value is stored in
straight binary format using four LSBs. Increments are possible
in steps of 1°C from 0°C to 15°C. The value in this register is
subtracted from the THIGH and TCRIT values and added to the
TLOW value to implement hysteresis.
The default setting for the THYST setpoint is 5°C.
THIGH SETPOINT REGISTER
The 16-bit THIGH setpoint register (Register Address 0x06) stores
the overtemperature limit value. An overtemperature event
occurs when the temperature value stored in the temperature
value register exceeds the value stored in this register. The INT pin
is activated if an overtemperature event occurs. The temperature
is stored in twos complement format with the most significant
bit being the temperature sign bit.
The default setting for the THIGH setpoint is 64°C.
TLOW SETPOINT REGISTER
The 16-bit TLOW setpoint register (Register Address 0x07) stores
the undertemperature limit value. An undertemperature event
occurs when the temperature value stored in the temperature
value register is less than the value stored in this register. The
INT pin is activated if an undertemperature event occurs. The
temperature is stored in twos complement format with the MSB
being the temperature sign bit.
The default setting for the TLOW setpoint is 10°C.
Table 12. THYST Setpoint Register (Register Address 0x05)
Bit
Default Value
Type
Name
Description
[3:0]
0101
R/W
THYST
Hysteresis value, from 0°C to 15°C. Stored in straight binary format. The default setting is 5°C.
[7:4]
0000
R/W
N/A
Not used.
Table 13. THIGH Setpoint Register (Register Address 0x06)
Bit
Default Value
Type
Name
Description
[15:0]
0x2000
R/W
THIGH
16-bit overtemperature limit, stored in twos complement format.
Table 14. TLOW Setpoint Register (Register Address 0x07)
Bit
Default Value
[15:0]
0x0500
Type
Name
Description
R/W
TLOW
16-bit undertemperature limit, stored in twos complement format.
Rev. A | Page 17 of 24
ADT7310
Data Sheet
SERIAL INTERFACE
PULL-UP
VDD
VDD
10kΩ
VDD
ADT7310
SCLK
DOUT
DIN
CS
GND
CT
INT
07789-014
MICROCONTROLLER
10kΩ
0.1µF
Figure 17. Typical SPI Interface Connection
The ADT7310 has a 4-wire serial peripheral interface (SPI). The
interface has a data input pin (DIN) for inputting data to the
device, a data output pin (DOUT) for reading data back from
the device, and a data clock pin (SCLK) for clocking data into
and out of the device. A chip select pin (CS) enables or disables
the serial interface. CS is required for correct operation of the
interface. Data is clocked out of the ADT7310 on the negative
edge of SCLK, and data is clocked into the device on the
positive edge of SCLK.
SPI COMMAND BYTE
All data transactions on the bus begin with the master taking
CS from high to low and sending out the command byte. This
indicates to the ADT7310 whether the transaction is a read or
a write and provides the address of the register for the data
transfer. Table 15 shows the command byte.
Bit C7 of the command byte must be set to 0 to successfully
begin a bus transaction. The SPI interface does not work
correctly if a 1 is written into this bit.
Bit C6 is the read/write bit; 1 indicates a read, and 0 indicates
a write.
Bits[C5:C3] contain the target register address. One register can
be read from or written to per bus transaction.
Bit C2 activates a continuous read mode on the temperature
value register only. When this bit is set, the serial interface is
configured so that the temperature value register can be
continuously read. When the command word is 01010100
(0x54), the contents of the temperature value register can be
read out without requiring repeated writes to set the address
bits. Simply sending 16 SCLK clocks to the ADT7310 clocks the
contents of the temperature value register onto the DOUT pin.
Table 15. Command Byte
C7
0
C6
R/W
C5
C4
C3
Register address
C2
Continuous
read
C1
0
C0
0
Rev. A | Page 18 of 24
Data Sheet
ADT7310
Figure 18 shows a write to an 8-bit register, and Figure 19 shows
a write to a 16-bit register.
WRITING DATA
Data is written to the ADT7310 in eight bits or 16 bits, depending
on the addressed register. The first byte written to the device is
the command byte, with the read/write bit set to 0. The master
then supplies the 8-bit or 16-bit input data on the DIN line.
The ADT7310 clocks the data into the register addressed in
the command byte on the positive edge of SCLK. The master
finishes the write by pulling CS high.
The master must begin a new write transaction on the bus for
every register write. Only one register is written to per bus
transaction.
CS
1
2
3
5
4
6
7
8
9
10
11
DIN
R/W
C7
C6
REGISTER ADDR
CONT
READ
0
0
C4
C2
C1
C0
C5
C3
13
14
15
16
8-BIT DATA
8-BIT COMMAND BYTE
0
12
D7
D5
D6
D4
D2
D3
D1
07789-028
SCLK
D0
Figure 18. Writing to an 8-Bit Register
CS
2
3
4
5
6
7
8
9
10
11
12
13
14
0
R/W
REGISTER ADDR
C7
C6
C5
C4
C3
16
22
17
23
CONT
READ
0
0
C2
C1
C0
D15
D14
D13
D12
D11
D10
D9
D8
D7
D2
D1
Figure 19. Writing to a 16-Bit Register
CS
SCLK
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
8-BIT COMMAND WORD
DIN
0
R/W
C7
C6
REGISTER ADDR
CONT
READ
0
0
C4
C2
C1
C0
C5
C3
8-BIT DATA
DOUT
24
16-BIT DATA
8-BIT COMMAND BYTE
DIN
15
D7
D6
D5
Figure 20. Read from an 8-Bit Register
Rev. A | Page 19 of 24
D4
D3
D2
D1
D0
D0
07789-029
1
07789-030
SCLK
ADT7310
Data Sheet
CS
SCLK
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
22
23
24
8-BIT COMMAND BYTE
DIN
0
R/W
C7
C6
CONT
REGISTER ADDR READ
C5
C4
C3
C2
0
0
C1
C0
DOUT
D15
D14
D13
D12
D11
D10
D9
D8
D7
D2
D1
D0
07789-031
16-BIT DATA
Figure 21. Read from a 16-Bit Register
READING DATA
A read transaction begins when the master writes the command
byte to the ADT7310 with the read/write bit set to 1. The master
then supplies 8 or 16 clock pulses, depending on the addressed
register, and the ADT7310 clocks out data from the addressed
register on the DOUT line. Data is clocked out on the first
falling edge of SCLK following the command byte.
The read transaction finishes when the master takes CS high.
DSPs. SCLK can continue to run between data transfers,
provided that the timing numbers are obeyed.
CS can be tied to ground, and the serial interface can be
operated in a 3-wire mode. DIN, DOUT, and SCLK are
used to communicate with the ADT7310 in this mode.
For microcontroller interfaces, it is recommended that SCLK
idle high between data transfers.
SERIAL INTERFACE RESET
The master must begin a new read transaction on the bus for
every register read. Only one register is read per bus transaction.
However, in continuous read mode, Command Byte C2 = 1, and
the temperature value register can be read from continuously.
The master sends 16 clock pulses on SCLK, and the temperature
value is clocked out on DOUT.
INTERFACING TO DSPs OR MICROCONTROLLERS
The ADT7310 can be operated with CS used as a frame synchronization signal. This scheme is useful for DSP interfaces.
In this case, the first bit (MSB) is effectively clocked out by CS
because CS normally occurs after the falling edge of SCLK in
The serial interface can be reset by writing a series of 1s on the
DIN input. If a Logic 1 is written to the ADT7310 line for at
least 32 serial clock cycles, the serial interface is reset. This
ensures that the interface can be reset to a known state if the
interface gets lost due to a software error or some glitch in the
system. Reset returns the interface to the state in which it is
expecting a write to the communications register. This operation resets the contents of all registers to their power-on values.
Following a reset, the user should allow a period of 500 µs
before addressing the serial interface.
Rev. A | Page 20 of 24
Data Sheet
ADT7310
INT AND CT OUTPUTS
Comparator Mode
The INT and CT pins are open drain outputs, and both pins
require a 10 kΩ pull-up resistor to VDD.
In comparator mode, the INT pin returns to its inactive status
when the temperature drops below the THIGH − THYST limit or
rises above the TLOW + THYST limit.
UNDERTEMPERATURE AND OVERTEMPERATURE
DETECTION
Putting the ADT7310 into shutdown mode does not reset the
INT state in comparator mode.
The INT and CT pins have two undertemperature/overtemperature modes: comparator mode and interrupt mode.
The interrupt mode is the default power-up overtemperature
mode. The INT output pin becomes active when the temperature is greater than the temperature stored in the THIGH setpoint
register or less than the temperature stored in the TLOW setpoint
register. How this pin reacts after this event depends on the
overtemperature mode selected.
Interrupt Mode
In interrupt mode, the INT pin goes inactive when any ADT7310
register is read. Once the INT pin is reset, it goes active again
only when the temperature is greater than the temperature
stored in the THIGH setpoint register or less than the temperature
stored in the TLOW setpoint register.
Figure 22 illustrates the comparator and interrupt modes for
events exceeding the THIGH limit with both pin polarity settings.
Figure 23 illustrates the comparator and interrupt modes for
events exceeding the TLOW limit with both pin polarity settings.
Placing the ADT7310 into shutdown mode resets the INT pin
in the interrupt mode.
TEMPERATURE
82°C
81°C
THIGH
80°C
79°C
78°C
77°C
76°C
THIGH – THYST
75°C
74°C
73°C
INT PIN
(COMPARATOR MODE)
POLARITY = ACTIVE LOW
INT PIN
(INTERRUPT MODE)
POLARITY = ACTIVE LOW
INT PIN
(COMPARATOR MODE)
POLARITY = ACTIVE HIGH
TIME
READ
READ
READ
07789-020
INT PIN
(INTERRUPT MODE)
POLARITY = ACTIVE HIGH
Figure 22. INT Output Temperature Response Diagram for THIGH Overtemperature Events
Rev. A | Page 21 of 24
ADT7310
Data Sheet
TEMPERATURE
–13°C
–14°C
TLOW + THYST
–15°C
–16°C
–17°C
–18°C
–19°C
TLOW
–20°C
–21°C
–22°C
INT PIN
(COMPARATOR MODE)
POLARITY = ACTIVE LOW
INT PIN
(INTERRUPT MODE)
POLARITY = ACTIVE LOW
INT PIN
(COMPARATOR MODE)
POLARITY = ACTIVE HIGH
TIME
READ
READ
READ
07789-021
INT PIN
(INTERRUPT MODE)
POLARITY = ACTIVE HIGH
Figure 23. INT Output Temperature Response Diagram for TLOW Undertemperature Events
Rev. A | Page 22 of 24
Data Sheet
ADT7310
APPLICATIONS INFORMATION
THERMAL RESPONSE TIME
TEMPERATURE MONITORING
The time required for a temperature sensor to settle to a
specified accuracy is a function of the thermal mass of the
sensor and the thermal conductivity between the sensor and
the object being sensed. Thermal mass is often considered
equivalent to capacitance. Thermal conductivity is commonly
specified using the symbol, Q, and can be thought of as thermal
resistance. It is commonly specified in units of degrees per watt
of power transferred across the thermal joint. The time required
for the part to settle to the desired accuracy is dependent on the
thermal contact established in that particular application, and
the equivalent power of the heat source. In most applications,
the settling time is best determined empirically.
The ADT7310 is ideal for monitoring the thermal environment
within hazardous automotive applications. The die accurately
reflects the exact thermal conditions that affect nearby
integrated circuits.
SUPPLY DECOUPLING
The ADT7310 should be decoupled with a 0.1 µF ceramic
capacitor between VDD and GND. This is particularly important
when the ADT7310 is mounted remotely from the power supply.
Precision analog products, such as the ADT7310, require a wellfiltered power source.
The ADT7310 measures and converts the temperature at the
surface of its own semiconductor chip. When the ADT7310 is
used to measure the temperature of a nearby heat source, the
thermal impedance between the heat source and the ADT7310
must be considered.
When the thermal impedance is determined, the temperature
of the heat source can be inferred from the ADT7310 output.
As much as 60% of the heat transferred from the heat source to
the thermal sensor on the ADT7310 die is discharged via the
copper tracks and the bond pads. Of the pads on the ADT7310,
the GND pad transfers most of the heat. Therefore, to measure
the temperature of a heat source, it is recommended that the
thermal resistance between the ADT7310 GND pad and the
GND of the heat source be reduced as much as possible.
Because the ADT7310 operates from a single supply, it may
seem convenient to tap into the digital logic power supply.
Unfortunately, the logic supply is often a switch-mode design,
which generates noise in the 20 kHz to 1 MHz range. In addition, fast logic gates can generate glitches hundreds of millivolts
in amplitude due to wiring resistance and inductance.
If possible, the ADT7310 should be powered directly from the
system power supply. This arrangement, shown in Figure 24,
isolates the analog section from the logic-switching transients.
Even if a separate power supply trace is not available, generous
supply bypassing reduces supply-line induced errors. Local
supply bypassing consisting of a 0.1 µF ceramic capacitor is
critical for the temperature accuracy specifications to be
achieved. This decoupling capacitor must be placed as close
as possible to the VDD pin of the ADT7310.
0.1µF
ADT7310
POWER
SUPPLY
07789-022
TTL/CMOS
LOGIC
CIRCUITS
Figure 24. Use of Separate Traces to Reduce Power Supply Noise
Rev. A | Page 23 of 24
ADT7310
Data Sheet
OUTLINE DIMENSIONS
5.00 (0.1968)
4.80 (0.1890)
1
5
4
1.27 (0.0500)
BSC
0.25 (0.0098)
0.10 (0.0040)
COPLANARITY
0.10
SEATING
PLANE
6.20 (0.2441)
5.80 (0.2284)
1.75 (0.0688)
1.35 (0.0532)
0.51 (0.0201)
0.31 (0.0122)
0.50 (0.0196)
0.25 (0.0099)
45°
8°
0°
0.25 (0.0098)
0.17 (0.0067)
1.27 (0.0500)
0.40 (0.0157)
COMPLIANT TO JEDEC STANDARDS MS-012-AA
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
012407-A
8
4.00 (0.1574)
3.80 (0.1497)
Figure 25. 8-Lead Standard Small Outline Package [SOIC_N]
Narrow Body
(R-8)
Dimensions shown in millimeters and (inches)
ORDERING GUIDE
Model 1
ADT7310TRZ
ADT7310TRZ-REEL
ADT7310TRZ-REEL7
EVAL-ADT7X10EBZ
1
2
Temperature Range
–55°C to +150°C
–55°C to +150°C
–55°C to +150°C
Temperature Accuracy 2
±0.5°C
±0.5°C
±0.5°C
Z = RoHS Compliant Part.
Maximum accuracy over the −40°C to +105°C temperature range.
©2009–2011 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D07789-0-12/11(A)
Rev. A | Page 24 of 24
Package Description
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead SOIC_N
Evaluation Board
Package Option
R-8
R-8
R-8