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ADT7312
Service Manual
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ANALOG DEVICES ADT7312 Service Manual

Automotive, ±1°C Accurate, 16-Bit, 175°C,
Digital SPI Temperature Sensor in Die Form
ADT7312
TEMPERATURE
VALUE
REGISTER
CONFIGURATION STATUS
REGISTER
ID
REGISTER
REGISTER
T
HYST
REGISTER
T
LOW
REGISTER
T
HIGH
REGISTER
T
CRIT
REGISTER
INTERNAL
REFERENCE
7
TEMPERATURE
SENSOR
T
HIGH
T
CRIT
T
LOW
INTERNAL
OSCILLATOR
FILTER
LOGIC
Σ-Δ
MODULATOR
GND
8
GND
9
V
DD
10
V
DD
6
5
CT
INT
3
4
1
2
SPI INTERFACE
ADT7312
06791-001
SCLK
DOUT
DIN
CS
Data Sheet

FEATURES

Qualified for automotive applications High performance
Temperature accuracy:
±1°C from −55°C to +175°C (2.7 V to 3.3 V) 16-bit temperature resolution: 0.0078°C Fast first temperature conversion on power-up of 6 ms
Easy implementation
No temperature calibration or correction required No linearity correction required
Low power
Power-saving 1 sample per second (SPS) mode 880 μW typical at 3.6 V in normal mode 9 μW typical at 3.6 V in shutdown mode
Wide operating ranges
Temperature range: −55°C to +175°C Voltage range: 2.7 V to 5.5 V
Programmable interrupts
Critical overtemperature interrupt Overtemperature/undertemperature interrupt
SPI-compatible interface Available in die form only

APPLICATIONS

Automotive High temperature monitoring High temperature thermal protection

FUNCTIONAL BLOCK DIAGRAM

GENERAL DESCRIPTION

The ADT7312 is a ±1°C accurate digital temperature sensor that operates over a very wide temperature range of −55°C to +175°C and is available in die form only. It contains an internal band gap reference, a temperature sensor, and a 16-bit analog­to-digital converter (ADC) to monitor and digitize the temper­ature to a resolution of 0.0078°C. The default ADC resolution is 13 bits (0.0625°C). The ADC resolution can be changed to 16 bits (0.0078°C) using the serial interface.
The ADT7312 is guaranteed to operate over supply voltages from 2.7 V to 5.5 V. At 3.6 V operation, the average supply current is typically 245 μA. The ADT7312 has a shutdown mode that powers down the device, resulting in a typical shutdown current of 2.5 μA at 3.6 V. The ADT7312 is rated for operation over the −55°C to +175°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 pin and the CT pin can operate in either comparator or interrupt mode.

PRODUCT HIGHLIGHTS

1. Ease of use, no calibration or correction required.
2. Low power consumption.
3. Excellent long-term stability and reliability.
4. Qualified for automotive applications.
Figure 1.
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
license is granted by implication or otherwise under any patent or patent rights of Analog Devi ces.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com
ADT7312 Data Sheet

TABLE OF CONTENTS

Features .............................................................................................. 1
Applications ....................................................................................... 1
General Description ......................................................................... 1
Product Highlights ........................................................................... 1
Functional Block Diagram .............................................................. 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
SPI Timing Specifications ........................................................... 4
Absolute Maximum Ratings ............................................................ 5
ESD Caution .................................................................................. 5
Pad Configuration and Function Descriptions ............................ 6
Die Bond Pad Coordinates .............................................................. 7
Typical Performance Characteristics ............................................. 8
Theory of Operation ........................................................................ 9
Circuit Description....................................................................... 9
Converter Architecture ................................................................ 9
Normal Mode (Continuous Conversion Mode) ...................... 9
One-Shot Mode .......................................................................... 10
1 SPS Mode .................................................................................. 11
Shutdown Mode .......................................................................... 11
Fault Queue ................................................................................. 11
Temperature Data Format ......................................................... 12
Temperature Conversion Formulas ......................................... 12
Registers ........................................................................................... 13
Status Register ............................................................................. 13
Configuration Register .............................................................. 14
Temperature Value Register ...................................................... 15
ID Register................................................................................... 15
T
Setpoint Register ............................................................... 15
CRIT
T
Setpoint Register ............................................................... 16
HYST
T
Setpoint Register .............................................................. 16
HIGH
T
Setpoint Register ............................................................... 16
LOW
Serial Interface ................................................................................ 17
SPI Command Byte .................................................................... 17
Writing Data ............................................................................... 18
Reading Data ............................................................................... 19
Interfacing to DSPs or Microcontrollers ................................. 19
Resetting the Serial Interface .................................................... 19
INT and CT Outputs ...................................................................... 20
Undertemperature and Overtemperature Detection ............ 20
Redundant Critical Generator .................................................. 21
Applications Information .............................................................. 22
Thermal Response Time ........................................................... 22
Supply Decoupling ..................................................................... 22
Powering from a Switching Regulator ..................................... 22
Temperature Monitoring ........................................................... 22
Quick Guide to Measuring Temperature ................................ 22
Outline Dimensions ....................................................................... 23
Ordering Guide .......................................................................... 23
Automotive Products ................................................................. 23

REVISION HISTORY

1/12—Revision 0: Initial Version
Rev. 0 | Page 2 of 24
Data Sheet ADT7312
Accuracy1
±1.0
°C
TA = −55°C to +175°C, VDD = 2.7 V to 3.3 V
Temperature Conversion Time
240 ms
Continuous and one-shot conversion modes
Input High Voltage, VIH
0.7 × VDD
V
1 SPS Mode
55 µA
VDD = 3.6 V, TA = 25°C

SPECIFICATIONS

TA = −55°C to +175°C, VDD = 2.7 V to 5.5 V, unless otherwise noted.
Table 1.
Parameter Min Typ Max Unit Test Conditions/Comments
TEMPERATURE SENSOR AND ADC
±1.1 °C TA = −55°C to +175°C, VDD = 3.3 V to 3.6 V ±1.2 °C TA = +150°C to +175°C, VDD = 4.5 V to 5.5 V ±1.5 °C TA = −55°C to +175°C, VDD = 4.5 V to 5.5 V
ADC Resolution 13 Bits
16 Bits
Temperature Resolution
13-Bit 0.0625 °C 13-bit resolution (sign bit plus 12 bits)
16-Bit 0.0078 °C 16-bit resolution (sign bit plus 15 bits)
Fast Temperature Conversion Time 6 ms First conversion on power-up only 1 SPS Conversion Time 60 ms 1 SPS mode Temperature Hysteresis ±0.002 °C Repeatability2 ±0.015 °C TA = 25°C
DC PSRR 0.1 °C/V TA = 25°C DIGITAL OUTPUTS (CT, INT) Open-drain outputs
High Output Leakage Current, IOH 0.1 5 µA CT and INT pins pulled up to 5.5 V Output Low Voltage, VOL 0.4 V IOL = 3 mA at 5.5 V, IOL = 1 mA at 3.3 V Output High Voltage, VOH 0.7 × VDD V Output Capacitance, C
DIGITAL INPUTS (DIN, SCLK, CS)
2 pF
OUT
Input Current, IIN ±1 µA VIN = 0 V to VDD Input Low Voltage, VIL 0.4 V
Twos complement temperature value of sign bit plus 12 bits (power-on default resolution)
Twos complement temperature value of sign bit plus 15 bits (Bit 7 = 1 in the configuration register)
Pin Capacitance, CIN 5 10 pF
DIGITAL OUTPUT (DOUT)
Output High Voltage, VOH VDD − 0.3 V I
SOURCE
= I
= 200 µA
SINK
Output Low Voltage, VOL 0.4 V IOL = 200 µA Output Capacitance, C
50 pF
OUT
POWER REQUIREMENTS
Supply Voltage 2.7 5.5 V Supply Current Peak current while converting; SPI interface inactive
Continuous Conversion Mode 245 320 µA VDD = 3.6 V
275 350 µA VDD = 5.5 V
70 µA VDD = 5.5 V, TA = 25°C
Shutdown Mode 2.5 40 µA VDD = 3.6 V
5.4 50 µA VDD = 5.5 V
Power Dissipation Power dissipated for VDD = 3.6 V, TA = 25°C
Continuous Conversion Mode 880 µW
1 SPS Mode 200 µW
Shutdown Mode 9 µW
1
Accuracy includes lifetime drift.
2
Based on a floating average of 10 readings.
Rev. 0 | Page 3 of 24
ADT7312 Data Sheet
t8 0 ns min
CS
SCLK
DIN
DOUT
t
1
1
8
76
MSB LSB
2 3
MSB
LSB
9 10 23 24
t
2
t
4
t
5
t
3
t
6
t
7
t
8
t
9
t
10
06791-002

SPI TIMING SPECIFICATIONS

TA = −55°C to +175°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 V
) and timed from a voltage level of 1.6 V.
DD
Table 2.
Parameter
t1 0 ns min
1, 2
Limit at T
MIN
, T
Unit Description
MAX
CS falling edge to SCLK active edge setup time t2 100 ns min SCLK high pulse width t3 100 ns min SCLK low pulse width t4 30 ns min Data setup time prior to SCLK rising edge t5 25 ns min Data hold time after SCLK rising edge t6 5 ns min Data access time after SCLK falling edge 60 ns max VDD = 4.5 V to 5.5 V 80 ns max VDD = 2.7 V to 3.6 V
3
t
10 ns min
7
Bus relinquish time after
CS inactive edge
80 ns max
SCLK inactive edge to CS rising edge hold time t9 0 ns min
CS falling edge to DOUT active time 60 ns max VDD = 4.5 V to 5.5 V 80 ns max VDD = 2.7 V to 3.6 V t10 10 ns min SCLK inactive edge to DOUT low
1
Sample tested during initial release to ensure compliance.
2
See Figure 2.
3
The t7 values are the true bus relinquish times of the part and, as such, are independent of external bus loading capacitances.
Figure 2. Detailed SPI Timing Diagram
Rev. 0 | Page 4 of 24
Data Sheet ADT7312
DIN Input Voltage to GND
−0.3 V to VDD + 0.3 V
Operating Temperature Range
−55°C to +175°C

ABSOLUTE MAXIMUM RATINGS

Table 3.
Parameter Rating
VDD to GND −0.3 V to +7 V
DOUT Output Voltage to GND −0.3 V to VDD + 0.3 V SCLK Input Voltage to GND −0.3 V to VDD + 0.3 V
175°C
JMAX
−0.3 V to V
CS Input Voltage to GND CT and INT Output Voltage to GND −0.3 V to VDD + 0.3 V ESD Rating (Human Body Model) 2.0 kV
Storage Temperature Range −65°C to +175°C Maximum Junction Temperature, T
+ 0.3 V
DD
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.

ESD CAUTION

Rev. 0 | Page 5 of 24
ADT7312 Data Sheet

PAD CONFIGURATION AND FUNCTION DESCRIPTIONS

1950µm
SCLK
DOUT
2350µm
DIN
CS
Figure 3. Metallization Picture
V
DD
V
DD
GND
GND
CT
INT
06791-004
Table 4. Pad Function Descriptions
Pad No. Pad Name Description
1 SCLK Serial Clock Input. The serial clock is used to clock data into and out of any register of the device. 2 DOUT Serial Data Output. Data is clocked out on the falling edge of SCLK and is valid on the rising edge of SCLK. 3 DIN
Serial Data Input. Data to be loaded into the control registers of the part is provided on this input. Data is clocked into the registers on the rising edge of SCLK.
4
CS
5 INT
Chip Select Input. The device is enabled when this pin is low. The device is disabled when this pin is high. Overtemperature and Undertemperature Indicator. Logic output. When the device is powered up, this output is an
active low interrupt by default. Open-drain configuration. A pull-up resistor is required, typically 10 kΩ.
6 CT
Critical Overtemperature Indicator. Logic output. The default power-on polarity is active low. Open-drain
configuration. A pull-up resistor is required, typically 10 kΩ. 7 GND Analog Ground. This pad must be connected directly to Pad 8 (digital ground). 8 GND Digital Ground. This pad must be connected directly to Pad 7 (analog ground). 9 VDD
Analog Supply Voltage (2.7 V to 5.5 V). This pad must be connected directly to Pad 10 (digital supply voltage). The
supply should be decoupled with a 0.1 μF ceramic capacitor to GND. 10 VDD
Digital Supply Voltage (2.7 V to 5.5 V). This pad must be connected directly to Pad 9 (analog supply voltage). The
supply should be decoupled with a 0.1 μF ceramic capacitor to GND.
Rev. 0 | Page 6 of 24
Data Sheet ADT7312
2
DOUT
−838
+831
7
GND
+838
+508

DIE BOND PAD COORDINATES

The following X and Y coordinates refer to the center of the bond pad and are referenced from the center of the die.
Table 5. Bond Pad Coordinates
Pad No. Pad Name X Coordinate (µm) Y Coordinate (µm)
1 SCLK −838 +1020
3 DIN −838 −863 4
5 INT +838 −1011 6 CT +838 −863
8 GND +838 +702 9 VDD +838 +857 10 VDD +838 +1008
CS
−838 −1011
Rev. 0 | Page 7 of 24
ADT7312 Data Sheet
–50–70 –30 –10 10 30 50 70 90 110 130 150
170
190
TEMPERAT URE E RROR (ºC)
TEMPERATURE (ºC)
06791-005
–0.4
–0.6
–0.8
–0.2
0
0.4
0.2
0.6
0.8
1.0
–50–70 –30 –10 10 30 50
70 90 110 130 150
170
190
TEMPERATURE ERROR (ºC)
TEMPERATURE (ºC)
06791-006
–1.0
–0.5
0
0.5
1.0
1.5
350
300
200
250
150
100
50
0
–60 –40 –20 0 20 40 60 80 100 120 140 160 180
I
DD
(µA)
TEMPERATURE (°C)
5V CONTINUOUS CONVERSI ON
3V CONTINUOUS CONVERSI ON
5V 1SPS
3V 1SPS
06791-007
0
5
10
15
20
25
30
–60 –40 –20 0 20 40 60 80 100 120 140 160 180
SHUTDOWN I
DD
(µA)
TEMPERATURE (°C)
06791-008
V
DD
= 2.7V
V
DD
= 3.0V
V
DD
= 3.6V
V
DD
= 4.5V
V
DD
= 5.0V
V
DD
= 5.5V
0
50
100
150
200
250
300
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
I
DD
(µA)
SUPPLY VOLTAGE (V)
CONTINUO US CONVERSION
06791-009
1SPS
0
1
2
3
4
5
6
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
SHUTDOWN I
DD
(µA)
SUPPLY VOLTAGE (V)
06791-010

TYPICAL PERFORMANCE CHARACTERISTICS

Figure 4. Temperature Accuracy at 3 V
Figure 7. Shutdown Current vs. Temperature
Figure 5. Temperature Accuracy at 5 V
Figure 6. Operating Supply Current vs. Temperature
Figure 8. Operating Supply Current vs. Supply Voltage
Figure 9. Shutdown Current vs. Supply Voltage
Rev. 0 | Page 8 of 24
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