ADT7311WTRZ-RL7 - ANALOG DEVICES - Datasheet.Directory

Automotive, ±0.5°C Accurate, 16-Bit

Digital SPI Temperature Sensor

Data Sheet ADT7311

Rev. 0

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FEATURES

Qualified for automotive 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 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: −40°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

APPLICATIONS

Battery management

Climate control and infotainment

Lighting

Powertrain

Thermocouple cold junction compensation

GPS

GENERAL DESCRIPTION

The ADT7311 is a high accuracy digital temperature sensor

in a narrow 8-lead SOIC package. It contains a band gap

temperature reference and a 16-bit ADC to monitor and digitize

the temperature to a 0.0078°C resolution. The ADC resolution,

by default, is set to 13 bits (0.0625°C). The ADC resolution is a

user programmable mode that can be changed through the

serial interface.

The ADT7311 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 A. The ADT7311 has a shutdown mode that

powers down the device and offers a shutdown current of

typically 2 A. The ADT7311 is rated for operation over the

−40°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.

PRODUCT HIGHLIGHTS

1. Ease of use, no calibration or correction required by the user.

2. Low power consumption.

3. Excellent long-term stability and reliability.

4. Packaged in an 8-lead SOIC, RoHS-compliant package.

FUNCTIONAL BLOCK DIAGRAM

INTERNAL

REFERENCE

TEMPERATURE

SENSOR

HIGH

CRIT

LOW

INTERNAL

OSCILLATOR

FILTER

LOGIC

Σ-∆

MODULATOR

GND

INT

ADT7311

SPI INTERFACE

TEMPERATURE

VALUE

CONFIGURATION,

STATUS, AND

ID REGISTERS

LOW

CRIT

HYST

HIGH

SCLK

DOUT

DIN

9050-001

Figure 1.

ADT7311 Data Sheet

Rev. 0 | Page 2 of 24

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

Pin Configuration and Function Descriptions............................. 6

Typical Performance Characteristics ............................................. 7

Theory of Operation ........................................................................ 9

Circuit Information...................................................................... 9

Converter Details.......................................................................... 9

Temperature Measurement ......................................................... 9

One-Shot Mode .......................................................................... 10

1 SPS Mode.................................................................................. 10

Shutdown..................................................................................... 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

TCRIT Setpoint Register ............................................................... 15

THYST Setpoint Register............................................................... 16

THIGH Setpoint Register .............................................................. 16

TLOW Setpoint Register ............................................................... 16

Serial Peripheral Interface ............................................................. 17

SPI Command Byte.................................................................... 17

Writing Data ............................................................................... 18

Reading Data............................................................................... 19

Interfacing to DSPs or Microcontrollers ................................. 19

Serial Interface Reset.................................................................. 19

INT and CT Outputs...................................................................... 20

Undertemperature and Overtemperature Detection ............ 20

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

9/11—Revision 0: Initial Version

Data Sheet ADT7311

Rev. 0 | Page 3 of 24

SPECIFICATIONS

TA = −40°C to +150°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

Accuracy1 −0.05 ±0.4 °C TA = −40°C to +105°C, VDD = 3.0 V

±0.44 °C TA = −40°C to +105°C, VDD = 2.7 V to 3.3 V

±0.5 °C TA = −40°C to +125°C, VDD = 3.0 V

±0.5 °C TA = −40°C to +105°C, VDD = 2.7 V to 3.6 V

±0.7 °C TA = −40°C to +150°C, VDD = 2.7 V to 3.6 V

±0.8 °C TA = −40°C to +105°C, VDD = 4.5 V to 5.5 V

±1.0 °C TA = −40°C to +150°C, VDD = 2.7 V to 5.5 V

ADC Resolution 13 Bits Twos complement temperature value of sign bit plus

12 ADC bits (power-up default resolution)

16 Bits

Twos complement temperature value of sign bit plus

15 ADC bits (Bit 7 = 1 in the configuration register)

Temperature Resolution

13-Bit 0.0625 °C 13-bit resolution (sign + 12 bits)

16-Bit 0.0078 °C 16-bit resolution (sign + 15 bits)

Temperature Conversion Time 240 ms Continuous conversion and one-shot conversion mode

Fast Temperature Conversion Time 6 ms First conversion on power-up only

1 SPS Conversion Time 60 ms Conversion time for 1 SPS mode

Temperature Hysteresis ±0.002 °C Temperature cycle = 25°C to 125°C and back to 25°C

Repeatability ±0.015 °C TA = 25°C

DC PSRR 0.1 °C/V TA = 25°C

DIGITAL OUTPUTS (CT, INT), OPEN

DRAIN

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 = 2 mA at 5.5 V, IOL = 1 mA at 3.3 V

Output High Voltage, VOH 0.7 ×

VDD

Output Capacitance, COUT 2 pF

DIGITAL INPUTS (DIN, SCLK, CS)

Input Current ±1 μA VIN = 0 V to VDD

Input Low Voltage, VIL 0.4 V

Input High Voltage, VIH 0.7 ×

VDD

Pin Capacitance 5 10 pF

DIGITAL OUTPUT (DOUT)

Output High Voltage, VOH VOH −

0.3

V ISOURCE = ISINK = 200 μA

Output Low Voltage, VOL 0.4 V IOL = 200 μA

Output Capacitance, COUT 50 pF

POWER REQUIREMENTS

Supply Voltage 2.7 5.5 V

Supply Current

At 3.3 V 210 265 μA Peak current while converting, SPI interface inactive

At 5.5 V 250 300 μA Peak current while converting, SPI interface inactive

1 SPS Current

At 3.3 V 46 μA VDD = 3.3 V, 1 SPS mode, TA = 25°C

At 5.5 V 65 μA VDD = 5.5 V, 1 SPS mode, TA = 25°C

ADT7311 Data Sheet

Rev. 0 | Page 4 of 24

Parameter Min Typ Max Unit Test Conditions/Comments

Shutdown Current

At 3.3 V 2.0 15 μA Supply current in shutdown mode

At 5.5 V 5.2 25 μA Supply current in shutdown mode

Power Dissipation Normal Mode 700 μW VDD = 3.3 V, normal mode at 25°C

Power Dissipation 1 SPS 150 μW Power dissipated for VDD = 3.3 V, TA = 25°C

1 Accuracy includes lifetime drift.

SPI TIMING SPECIFICATIONS

TA = −40°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 Unit Conditions/Comments

t1 0 ns min 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

t73 10 ns min Bus relinquish time after CS inactive edge

80 ns max

t8 0 ns min 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. 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.

2 See Figure 2.

3 This means that the times quoted in the timing characteristics in Table 2 are the true bus relinquish times of the part and, as such, are independent of external bus

loading capacitances.

SCLK

DIN

DOUT

MSB LSB

9102324

t4t5

t9t10

09050-002

Figure 2. Detailed SPI Timing Diagram

Data Sheet ADT7311

Rev. 0 | Page 5 of 24

ABSOLUTE MAXIMUM RATINGS

Table 3.

Parameter Rating

VDD to GND −0.3 V to +7 V

DIN Input Voltage to GND −0.3 V to VDD + 0.3 V

DOUT Voltage to GND −0.3 V to VDD + 0.3 V

SCLK Input Voltage to GND −0.3 V to VDD + 0.3 V

CS Input Voltage to GND −0.3 V to VDD + 0.3 V

CT and INT Output Voltage to GND −0.3 V to VDD + 0.3 V

ESD Rating (Human Body Model) 2.0 kV

Operating Temperature Range1 −40°C to +150°C

Storage Temperature Range −65°C to +160°C

Maximum Junction Temperature, TJMAX 150°C

8-Lead SOIC_N (R-8)

Power Dissipation2 W

MAX = (TJMAX − TA3)/θJA

Thermal Impedance4

θJA, Junction-to-Ambient (Still Air) 121°C/W

θJC, Junction-to-Case 56°C/W

IR Reflow Soldering 220°C

Peak Temperature (RoHS-Compliant

Package)

260°C (0°C)

Time at Peak Temperature 20 sec to 40 sec

Ramp-Up Rate 3°C/sec maximum

Ramp-Down Rate −6°C/sec maximum

Time from 25°C to Peak Temperature 8 minutes maximum

1 Operating at extended temperatures over prolonged periods depends on

the lifetime performance of the part. Consult your local Analog Devices, Inc.,

account representative for more details.

2 Value relates to package being used on a standard 2-layer PCB. This gives a

worst-case θJA and θJC.

3 TA = ambient temperature.

4 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.

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

ADT7311 Data Sheet

Rev. 0 | Page 6 of 24

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

SCLK

DOUT

DIN

GND

INT

ADT7311

TOP VIEW

(Not to Scale)

09050-005

Figure 3. Pin Configuration

Table 4. Pin Function Descriptions

Pin No. Mnemonic Description

1 SCLK Serial Clock Input. The serial clock is used to clock in and clock out data to and from any register of the ADT7311.

2 DOUT Serial Data Output. Data is clocked out on the SCLK falling edge and is valid on the SCLK rising edge.

3 DIN 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.

4 CS Chip Select Input. The device is selected when this input is low. The device is disabled when this pin is high.

5 INT Overtemperature and Undertemperature Indicator. Logic output. The power-up default setting is as an active

low comparator interrupt. Open-drain configuration. A pull-up resistor is required, typically 10 kΩ.

6 CT Critical Overtemperature Indicator. Logic output. Power-up default polarity is active low. Open-drain

configuration. A pull-up resistor is required, typically 10 kΩ.

7 GND Analog and Digital Ground.

8 VDD Positive Supply Voltage (2.7 V to 5.5 V). The supply should be decoupled with a 0.1 μF ceramic capacitor to GND.

Data Sheet ADT7311

Rev. 0 | Page 7 of 24

TYPICAL PERFORMANCE CHARACTERISTICS

100

150

200

250

300

–100 –50 0 50 100 150 200

TEMPERATURE (°C)

3.0V 1SPS

5.5V 1SPS

5.5V CONTINUOUS

CONVERSION

3.0V CONTINUOUS

CONVERSION

9050-007

(µA)

–60 –40 –20 0 20 40 60 80 100 120 140 160

TEMPER

TURE ERROR (°C)

TEMPERATURE (°C)

–1.0

–0.8

–0.6

–0.4

–0.2

0.2

0.4

0.6

0.8

1.0

MAX ACCURACY LIMITS

09050-006

Figure 4. Temperature Accuracy at 3 V Figure 6. Operating Supply Current vs. Temperature

3.6V

(µA)

TEMPERATURE (°C)

–100 –50 0 50 100 150 200

3.0V

2.7V

4.5V

5.0V

5.5V

09050-025

–1.0

–0.8

–0.6

–0.4

–0.2

0.2

0.4

0.6

0.8

1.0

–60 –40 –20 0 20 40 60 80 100 120 140 160

TEMPER

TURE ERROR (°C)

TEMPERATURE (°C)

MAX ACCURACY LIMITS

09050-024

Figure 7. Shutdown Current vs. Temperature

Figure 5. Temperature Accuracy at 5 V

ADT7311 Data Sheet

Rev. 0 | Page 8 of 24

100

150

200

250

300

2.53.03.54.04.55.05.56.0

(

µA)

SUPPLY VOLTAGE (V)

CONTINUOUS CONVERSION

1SPS

09050-008

Figure 8. Average Operating Supply Current vs. Supply Voltage at 25°C

2.53.03.54.04.55.05.56.0

SHUTDOWN IDD (µA)

SUPPLY VOLTAGE (V)

9050-009

Figure 9. Shutdown Current vs. Supply Voltage at 25°C

100

120

140

160

043530252015105

TEMPERATURE (°C)

TIME (Seconds)

09050-011

Figure 10. Response to Thermal Shock

Data Sheet ADT7311

Rev. 0 | Page 9 of 24

THEORY OF OPERATION

CIRCUIT INFORMATION

The ADT7311 is a high accuracy digital temperature sensor that

uses a 16-bit ADC to monitor and digitize the temperature to

0.0078°C of resolution. The ADC resolution, by default, is set to

13 bits (0.0625°C). An internal temperature sensor generates a

voltage proportional to absolute temperature, which is com-

pared to an internal voltage reference and input into a precision

digital modulator.

The internal temperature sensor has high accuracy and linearity

over the entire rated temperature range without needing correc-

tion or calibration by the user.

The sensor output is digitized by a sigma-delta (Σ-∆) modulator,

also known as the charge balance type analog-to-digital conver-

ter. This type of converter utilizes time-domain oversampling

and a high accuracy comparator to deliver 16 bits of resolution

in an extremely compact circuit.

CONVERTER DETAILS

The Σ-∆ 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.

Σ-∆ MODULATOR

INTEGRATOR

COMPARATOR

TEMPERATURE

VALUE

CLOCK

GENERATOR

LPF DIGITAL

FILTER

1-BIT

DAC

VOLTAGE REF

AND VPTAT

1-BIT

13-BIT/

16-BIT

09050-012

Figure 11. Σ-∆ Modulator

TEMPERATURE MEASUREMENT

In normal mode (default power-up mode), the ADT7311 runs

an automatic conversion sequence. During this automatic

conversion sequence, a conversion typically takes 240 ms to

complete and the ADT7311 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

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.

ADT7311 Data Sheet

Rev. 0 | Page 10 of 24

DIN 0x08 0x20

DATA

SCLK

DOUT

WAIT 240ms MINIMUM

FOR CONVERSION TO FINISH

09050-026

Figure 12. Typical SPI One-Shot Write to Configuration Register Followed by a Read from the Temperature Value Register

ONE-SHOT MODE

Setting Bit 6 to 0 and Bit 5 to 1 of the configuration register

(Register Address 0x01) enables the one-shot mode. When

this mode is enabled, the ADT7311 immediately completes a

conversion and then goes into shutdown mode.

Wait for a minimum of 240 ms after writing to the operation

mode bits before reading back the temperature from the

temperature value register. This time ensures that the ADT7311

has time to power up and complete a conversion.

To obtain an updated temperature conversion, reset the Bit 6 to

0 and Bit 5 to 1 in the configuration register (0x01).

The one-shot mode is useful when one of the circuit design

priorities is to reduce power consumption.

1 SPS MODE

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).

Data Sheet ADT7311

Rev. 0 | Page 11 of 24

CT and INT Operation in One-Shot Mode

See Figure 13 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 comparator mode, if the temperature drops

below the THIGH – THYST value or goes above the TLOW + THYST

value, a write to the operation mode bits (Bit 5 and Bit 6 of

the configuration register, Register Address 0x01) resets the

INT pin.

For the CT pin in comparator mode, if the temperature

drops below the TCRIT – THYST value, a write to the operation

mode bits (Bit 5 and Bit 6 of the configuration register,

When using one-shot mode, ensure that the refresh rate is

appropriate to the application being used.

SHUTDOWN

The ADT7311 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 ADT7311 can be taken out of shutdown

mode by writing 0 to Bit 6 and 0 to Bit 5 of the configuration

1 ms (with a 0.1 µF decoupling capacitor) to come out of shut-

down mode. The conversion result from the last conversion

prior to shutdown can still be read from the ADT7311 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.

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 ADT7311 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 tempera-

ture 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 0.

TEMPE

TURE

149°C

148°C

147°C

146°C

145°C

144°C

143°C

142°C

141°C

140°C

CT PIN

POLARITY = ACTIVE LOW

CT PIN

POLARITY = ACTIVE HIGH

CRIT

CRIT – THYST

TIME

*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.

WRITE TO

BIT 5 AND BIT 6 OF

CONFIGURATION

WRITE TO

BIT 5 AND BIT 6 OF

CONFIGURATION

WRITE TO

BIT 5 AND BIT 6 OF

CONFIGURATION

09050-013

Figure 13. One-Shot CT Pin

ADT7311 Data Sheet

Rev. 0 | Page 12 of 24

TEMPERATURE DATA FORMAT

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 ADT7311 is guaranteed to measure a low value

temperature limit of −40°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.

Temperature data in the temperature value register, the TCRIT

setpoint register, the THIGH setpoint register, and the TLOW

setpoint register is 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.

Tabl e 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 ADT7311 by ignoring the last four

LSBs of the 13-bit temperature value. These four LSBs are Bit 3

to Bit 6 in Tabl e 5.

Table 5. 13-Bit Temperature Data Format

Temperature

Digital Output

(Binary) Bits[15:3]

Digital

Output (Hex)

−40°C 1 1100 1110 0000 0x1CE0

−25°C 1 1110 0111 0000 0x1E70

−0.0625°C 1 1111 1111 1111 0x1FFF

0°C 0 0000 0000 0000 0x000

+0.0625°C 0 0000 0000 0001 0x001

+25°C 0 0001 1001 0000 0x190

+50°C 0 0011 0010 0000 0x320

+125°C 0 0111 1101 0000 0x7D0

+150°C 0 1001 0110 0000 0x960

TEMPERATURE CONVERSION FORMULAS

16-Bit Temperature Data Format

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

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.

Data Sheet ADT7311

Rev. 0 | Page 13 of 24

REGISTERS

The ADT7311 contains eight registers:

• A status register

• A configuration register

• Five temperature registers

• An ID register

The status register, temperature value register, and the ID

Table 6. ADT7311 Registers

Address Description

Power-On

Default

0x00 Status 0x80

0x01 Configuration 0x00

0x02 Temperature value 0x0000

0x03 ID 0xC3

0x04 TCRIT setpoint 0x4980 (147°C)

0x05 THYST setpoint 0x05 (5°C)

0x06 THIGH setpoint 0x2000 (64°C)

0x07 TLOW setpoint 0x0500 (10°C)

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 tempera-

ture 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 operation mode bits.

Table 7. Status Register (Register Address 0x00)

Bit

Default

Value Type Name Description

[3:0] 0000 R Unused Reads back 0.

4 0 R TLOW 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.

5 0 R THIGH This bit is set to 1 when the temperature rises above the THIGH temperature limit. The bit clears to 0

when the status register is read and/or when the temperature measured drops below the limit set

in the THIGH − THYST setpoint registers.

6 0 R TCRIT This bit is set to 1 when the temperature rises above the TCRIT temperature limit. This bit clears to 0

when the status register is read and/or when the temperature measured drops below the limit set

in the TCRIT − THYST setpoint registers.

7 1 R

RDY This bit goes low when the temperature conversion result is written into the temperature value

this bit is reset after a write to the operation mode bits.

ADT7311 Data Sheet

Rev. 0 | Page 14 of 24

CONFIGURATION REGISTER

This 8-bit read/write register (Register Address 0x01) stores various

configuration modes for the ADT7311, 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

Default

Value Type Name Description

[1:0] 00 R/W Fault queue 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.

2 0 R/W CT pin polarity This bit selects the output polarity of the CT pin.

0 = active low.

1 = active high.

3 0 R/W INT pin polarity This bit selects the output polarity of the INT pin.

0 = active low.

1 = active high.

4 0 R/W INT/CT mode This bit selects between comparator mode and interrupt mode.

0 = interrupt mode.

1 = comparator mode.

[6:5] 00 R/W Operation mode These two bits set the operational mode for the ADT7311.

00 = continuous conversion (default). When one conversion is finished, the ADT7311

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.

7 0 R/W Resolution 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 0.0078°C.

Data Sheet ADT7311

Rev. 0 | Page 15 of 24

TEMPERATURE VALUE 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.

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.

ID REGISTER

This 8-bit read-only register (Register Address 0x03) stores

the manufacturer ID in Bit 7 to Bit 3 and the silicon revision

in Bit 2 to Bit 0.

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 tempera-

ture 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 Default Value Type Name Description

0 0 R TLOW flag/LSB0 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).

1 0 R THIGH flag/LSB1 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).

2 0 R TCRIT flag/LSB2 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).

[7:3] 00000 R Temp Temperature value in twos complement format.

[14:8] 0000000 R Temp Temperature value in twos complement format.

15 0 R Sign Sign bit, indicates if the temperature value is negative or positive.

Table 10. ID Register (Register Address 0x03)

Bit Default Value Type Name Description

[2:0] 011 R Revision ID Contains the silicon revision identification number.

[7:3] 11000 R Manufacturer ID 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.

ADT7311 Data Sheet

Rev. 0 | Page 16 of 24

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 Type Name Description

[15:0] 0x0500 R/W TLOW 16-bit undertemperature limit, stored in twos complement format.

Data Sheet ADT7311

Rev. 0 | Page 17 of 24

SERIAL PERIPHERAL INTERFACE

ADT7311

GND

SCLK

DOUT

DIN CT

INT

10kΩ10kΩ

PULL-UP

0.1µF

MICROCONTROLLER

09050-014

Figure 14. Typical SPI Interface Connection

The ADT7311 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 on the negative

edge of SCLK, and data is clocked into the device on the

positive edge of SCLK.

ADT7311

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 whether the transaction is a read or

a write and provides the address of the register for the data

transfer. shows the format of the command byte.

ADT7311

Table 1 5

Table 15. Command Byte

C7 C6 C5 C4 C3 C2 C1 C0

0 R/W Register address 0 0 0

Bit C7, Bit C2, Bit C1, and Bit C0 of the command byte must all

be set to 0 to successfully begin a bus transaction. The SPI

interface does not work correctly if a 1 is written into any of

these bits.

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.

ADT7311 Data Sheet

Rev. 0 | Page 18 of 24

WRITING DATA

Data is written to the ADT7311 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 ADT7311 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.

Figure 15 shows a write to an 8-bit register, and Figure 16 shows

a write to a 16-bit register.

The master must begin a new write transaction on the bus for

every register write. Only one register is written to per bus

transaction.

C3 C2

C5 C4

DIN C7 C6 C1 D2 D1 D0

8-BIT DATA

5 6 7 8 9 10111213141516

SCLK 1234

R/W REGISTER ADDR

0000

D4 D3D7 D6

8-BIT COMMAND BYTE

09050-028

Figure 15. Writing to an 8-Bit Register

C3 C2C5 C4

DIN C7 C6 C1 D2 D1 D0

16-BIT DATA

524

6 7 8 9 10 11 12 13 14 15 16 22 23

SCLK 1234

D14 D13

R/W REGISTER ADDR

000 0

D12 D10D11 D9 D8 D7D15

8-BIT COMMAND BYTE

09050-029

Figure 16. Writing to a 16-Bit Register

Data Sheet ADT7311

Rev. 0 | Page 19 of 24

READING DATA

A read transaction begins when the master writes the command

byte to the ADT7311 with the read/write bit set to 1. The master

then supplies eight or 16 clock pulses, depending on the addressed

falling edge of SCLK following the command byte.

The read transaction finishes when the master takes CS high.

INTERFACING TO DSPs OR MICROCONTROLLERS

The ADT7311 can be operated with CS used as a frame syn-

chronization 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

DSPs. SCLK can continue to run between data transfers,

provided that the timing specifications in Table 2 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 ADT7311 in this mode.

For microcontroller interfaces, it is recommended that SCLK

idle high between data transfers.

SERIAL INTERFACE RESET

The serial interface can be reset by writing a series of 1s on the

DIN input. If a Logic 1 is written to the ADT7311 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 opera-

tion 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.

09050-030

C3 C2

C5 C4

DIN C7 C6 C1 C0

8-BIT DATA

5678910 11 12 13 14 15 16

SCLK

1234

D6 D5

R/W REGISTER ADDR

000

D4 D3 D2 D1 D0

DOUT

8-BIT COMMAND WORD

Figure 17. Reading from an 8-Bit Register

9050-031

C3 C2

C5 C4

DIN C7 C6 C1

D2 D1 D0

16-BIT DATA

524

6 7 8 9 10 11 12 13 14 15 16 22 23

SCLK 1234

D14 D13

R/W REGISTER ADDR

000

D12 D11 D10 D9 D8 D7

D15

DOUT

8-BIT COMMAND BYTE

Figure 18. Reading from a 16-Bit Register

ADT7311 Data Sheet

Rev. 0 | Page 20 of 24

INT AND CT OUTPUTS

The INT and CT pins are open-drain outputs, and both pins

require a 10 kΩ pull-up resistor to VDD. The ADT7311 must be

fully powered up to VDD before reading INT and CT data.

UNDERTEMPERATURE AND OVERTEMPERATURE

DETECTION

The INT and CT pins have two undertemperature/over-

temperature modes: comparator mode and interrupt mode.

The interrupt mode is the default power-up overtemperature

mode. The INT output pin becomes active when the tempera-

ture is greater than the temperature stored in the THIGH setpoint

overtemperature mode selected.

Figure 19 illustrates the comparator and interrupt modes for

events exceeding the THIGH limit with both pin polarity settings.

Figure 20 illustrates the comparator and interrupt modes for

events exceeding the TLOW limit with both pin polarity settings.

Comparator Mode

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.

Putting the ADT7311 into shutdown mode does not reset the

INT state in comparator mode.

Interrupt Mode

In interrupt mode, the INT pin goes inactive when any ADT7311

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.

Placing the ADT7311 into shutdown mode resets the INT pin

in the interrupt mode.

TEMPE

TURE

82°C

81°C

80°C

79°C

78°C

77°C

76°C

75°C

74°C

73°C

INT PIN

(COMPARATOR MODE)

POLARITY = ACTIVE LOW

INT PIN

(INTERRUPT MODE)

POLARITY = ACTIVE LOW

INT PIN

(INTERRUPT MODE)

POLARITY = ACTIVE HIGH

INT PIN

(COMPARATOR MODE)

POLARITY = ACTIVE HIGH

HIGH

– T

HYST

TIME

READ READ READ

09050-020

Figure 19. INT Output Temperature Response Diagram for THIGH Overtemperature Events

Data Sheet ADT7311

Rev. 0 | Page 21 of 24

TEMPER

TURE

–13°C

–14°C

–15°C

–16°C

–17°C

–18°C

–19°C

–20°C

–21°C

–22°C

INT PIN

(COMPARATOR MODE)

POLARITY = ACTIVE LOW

INT PIN

(INTERRUPT MODE)

POLARITY = ACTIVE LOW

INT PIN

(INTERRUPT MODE)

POLARITY = ACTIVE HIGH

INT PIN

(COMPARATOR MODE)

POLARITY = ACTIVE HIGH

LOW

+ T

HYST

LOW

TIME

READ READ READ

09050-021

Figure 20. INT Output Temperature Response Diagram for TLOW Undertemperature Events

ADT7311 Data Sheet

Rev. 0 | Page 22 of 24

APPLICATIONS INFORMATION

THERMAL RESPONSE TIME

Thermal response is a function of the thermal mass of the

temperature sensor, but it is also heavily influenced by the mass

of the object the IC is mounted to. For example, a large PCB

containing large amounts of copper tracking can act as a large

heat sink and slow the thermal response. For a faster thermal

response, it is recommended to mount the sensor on as small a

PCB as possible.

SUPPLY DECOUPLING

The ADT7311 must have a decoupling capacitor connected

between VDD and GND; otherwise, incorrect temperature

readings will be obtained. A 0.1 µF decoupling capacitor, such

as a high frequency ceramic type, must be used and mounted as

close as possible to the VDD pin of the ADT7311.

If possible, the ADT7311 should be powered directly from the

system power supply. This arrangement, shown in Figure 21,

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.

0.1µF

ADT7311

TTL/CMOS

LOGIC

CIRCUITS

POWER

SUPPLY

09050-022

Figure 21. Use of Separate Traces to Reduce Power Supply Noise

POWERING FROM A SWITCHING REGULATOR

Precision analog devices such as the ADT7311 require a well-

filtered power source. If the ADT7311 is powered from a

switching regulator, noise may be generated in the 50 kHz to

3 MHz range that may affect the temperature accuracy specifica-

tion. To prevent this, it is recommended to connect an RC filter

between the power supply and VDD. The value of components

used should be carefully considered to ensure that the

ADT7311 operates within specification. The RC filter should be

mounted as far away as possible from the ADT7311 to ensure

that the thermal mass is kept as low as possible. For additional

information, contact Analog Devices.

TEMPERATURE MONITORING

The ADT7311 is ideal for monitoring the thermal environment

within hazardous automotive applications. The die accurately

reflects the thermal conditions that affect nearby integrated

circuits.

The ADT7311 measures and converts the temperature at the

surface of its own semiconductor chip. When the ADT7311 is

used to measure the temperature of a nearby heat source, the

thermal impedance between the heat source and the ADT7311

must be considered.

When the thermal impedance is determined, the temperature

of the heat source can be inferred from the ADT7311 output.

As much as 60% of the heat transferred from the heat source to

the thermal sensor on the ADT7311 die is discharged via the

copper tracks and the bond pads. Of the pads on the ADT7311,

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 ADT7311 GND pad and the

GND of the heat source be reduced as much as possible.

QUICK GUIDE TO MEASURING TEMPERATURE

1. After power-up, reset the serial interface (load 32 consecutive

1s on DIN). This ensures all internal circuitary is properly

initialized.

2. Verify the setup by reading the device ID (Register Address

0x03). It should read 0xC3.

3. After consistent consecutive readings are obtained from

Step 2, proceed to read the configuration register (0x01),

TCRIT (0x04), THIGH (0x06), and TLOW (0x07). Compare to

the specified defaults in Table 6 . If all the readings match,

the interface is operational.

4. Write to the configuration register to set theADT7311 to

the desired configuration. Read the temperature value

Data Sheet ADT7311

Rev. 0 | Page 23 of 24

OUTLINE DIMENSIONS

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.

COMPLIANT TO JEDEC STANDARDS MS-012-AA

012407-A

0.25 (0.0098)

0.17 (0.0067)

1.27 (0.0500)

0.40 (0.0157)

0.50 (0.0196)

0.25 (0.0099) 45°

8°

0°

1.75 (0.0688)

1.35 (0.0532)

SEATING

PLANE

0.25 (0.0098)

0.10 (0.0040)

5.00 (0.1968)

4.80 (0.1890)

4.00 (0.1574)

3.80 (0.1497)

1.27 (0.0500)

BSC

6.20 (0.2441)

5.80 (0.2284)

0.51 (0.0201)

0.31 (0.0122)

COPLANARITY

0.10

Figure 22. 8-Lead Standard Small Outline Package [SOIC_N]

Narrow Body

(R-8)

Dimensions shown in millimeters and (inches)

ORDERING GUIDE

Model1, 2 Temperature Range3 Temperature Accuracy4 Package Description Package Option

ADT7311WTRZ –40°C to +150°C ±0.5°C 8-Lead SOIC_N R-8

ADT7311WTRZ-RL –40°C to +150°C ±0.5°C 8-Lead SOIC_N R-8

ADT7311WTRZ-RL7 –40°C to +150°C ±0.5°C 8-Lead SOIC_N R-8

EVAL-ADT7X10EBZ Evaluation Board

1 Z = RoHS Compliant Part.

2 W = Qualified for Automotive Applications.

3 Operating at extended temperatures over prolonged periods depends on the lifetime performance of the part.

4 Maximum accuracy over the −40°C to +105°C temperature range (VDD = 2.7 V to 3.6 V)

AUTOMOTIVE PRODUCTS

The ADT7311W models are available with controlled manufacturing to support the quality and reliability requirements of automotive

applications. Note that these automotive models may have specifications that differ from the commercial models; therefore, designers

should review the Specifications section of this data sheet carefully. Only the automotive grade products shown are available for use in

automotive applications. Contact your local Analog Devices account representative for specific product ordering information and to

obtain the specific Automotive Reliability reports for these models.

ADT7311 Data Sheet

Rev. 0 | Page 24 of 24

NOTES

registered trademarks are the property of their respective owners.

D09050-0-9/11(0)