ANALOG DEVICES ADT7320 Service Manual

±0.25°C Accurate, 16-Bit Digital

ADT7320

Rev. PrD

Preliminary Technical Data

FEATURES

High performance

Temperature accuracy

±0.20°C from −10°C to +85°C at 3.0 V to 3.3V

±0.25°C from −20°C to +105°C at 3.0 V to 3.6 V
16-bit temperature resolution: 0.0078°C
Ultralow temperature drift: 0.0073°C
NIST traceable or equivalent
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: −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
16-lead, RoHS-compliant, 4 mm × 4 mm LFCSP package

SPI Temperature Sensor

GENERAL DESCRIPTION

The ADT7320 is a high accuracy digital temperature sensor that
o

ffers breakthrough performance over a wide industrial temperature
range, housed in a 4 mm × 4 mm LFCSP package. It contains an
internal band gap reference, a temperature sensor, and a 16-bit
analog-to-digital converter (ADC) to monitor and digitize the
temperature to a resolution of 0.0078°C. 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 ADT7320 is guaranteed to operate over supply voltages from

.7 V to 5.5 V. Operating at 3.3 V, the average supply current is

2
typically 210 µA. The ADT7320 has a shutdown mode that powers
down the device and offers a shutdown current of typically 2.0 µA
at 3.3 V. The ADT7320 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 INT pin is also an open-drain output that becomes active
when the temperature exceeds a programmable limit. The INT pin
and CT pin can operate in either comparator or interrupt mode.

APPLICATIONS

RTD and thermistor replacement
Thermocouple cold junction compensation
Medical equipment
Industrial control and test
Food transportation and storage
Environmental monitoring and HVAC
Laser diode temperature control

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
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.

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. High accuracy for industrial, instrumentation, and medical

applications.

5. Packaged in a 16-lead, RoHS-compliant, 4 mm × 4 mm

LFCSP package.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] ©2011 Analog Devices, Inc. All rights reserved.

ADT7320 Preliminary Technical Data

DOUT

FUNCTIONAL BLOCK DIAGRAM

SCLK

DIN

CS

TEMPERATURE

VALUE

REGISTER

CONFIGURATION

REGISTER

T

REGISTER

T

REGISTER

1

2

3

4

CRIT

HIGH

SPI

INTERFACE

T

LOW

REGISTER

T

HYST

REGISTER

STATUS

REGISTER

ID

REGISTER

INTERNAL

REFERENCE

TEMPERATURE

SENSOR

INTERNAL

OSCILLATOR

Σ-∆

MODULATOR

FILTER

LOGIC

T

T

T

CRIT

HIGH

LOW

ADT7320

10

CT

9

INT

11

GND

12

V

DD

Figure 1.

Rev. PrD | Page 2 of 26

Preliminary Technical Data ADT7320

TABLE OF CONTENTS

Features ............................................................................................... 1

Applications ....................................................................................... 1

General Description .......................................................................... 1

Product Highlights ............................................................................ 1

Functional Block Diagram ............................................................... 2

Revision History ................................................................................ 3

Specifications ..................................................................................... 4

SPI Timing Specifications ............................................................ 5

Absolute Maximum Ratings ............................................................ 7

ESD Caution .................................................................................. 7

Pin Configuration and Function Descriptions ............................. 8

Typical Performance Characteristics .............................................. 9

Theory of Operation ....................................................................... 11

Circuit Information .................................................................... 11

Converter Details ........................................................................ 11

Continuous Conversion Mode .................................................. 11

One-Shot Mode ........................................................................... 12

1 SPS Mode .................................................................................. 13

Shutdown Mode .......................................................................... 13

Fault Queue .................................................................................. 13

Temperature Data Format .......................................................... 14

Temperature Conversion Formulas .......................................... 14

Registers ............................................................................................ 15

Status Register .............................................................................. 15

Configuration Register ............................................................... 16

Temperature Value Register ....................................................... 17

ID Register ................................................................................... 17

T

Setpoint Register ................................................................ 17

CRIT

T

Setpoint Register ............................................................... 18

HYST

T

Setpoint Register ............................................................... 18

HIGH

T

Setpoint Register ................................................................ 18

LOW

Serial Interface ................................................................................. 19

SPI Command Byte .................................................................... 19

Writing Data ................................................................................ 20

Reading Data ............................................................................... 21

Interfacing to DSPs or Microcontrollers .................................. 21

Serial Interface Reset .................................................................. 21

INT and CT Outputs ...................................................................... 22

Undertemperature and Overtemperature Detection ............. 22

Applications Information ............................................................... 24

Thermal Response Time ............................................................ 24

Supply Decoupling ...................................................................... 24

Powering from a Switching Regulator...................................... 24

Temperature Measurement ........................................................ 24

Quick Guide to Measuring Temperature ................................. 24

Outline Dimensions ........................................................................ 25

Ordering Guide ........................................................................... 25

REVISION HISTORY

11/11— Revision Pr. D: Preliminary Version

Rev. PrD | Page 3 of 26

ADT7320 Preliminary Technical Data

SPECIFICATIONS

TA = −40°C to +125°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

Accuracy
±0.25

±0.30 °C TA = −40°C to +105°C, VDD = 3.0 V
±0.35 °C TA = −40°C to +105°C, VDD = 2.7 V to 3.3 V
±0.50 °C TA = −40°C to +125°C, VDD = 3.0 V to 3.6 V
±0.503 °C TA = −10°C to +105°C, VDD = 4.5 V to 5.5 V
±0.65 °C TA = −40°C to +125°C, VDD = 4.5 V to 5.5 V

−0.85 °C TA = +150°C, VDD = 4.5 V to 5.5 V

−1.0 °C TA = +150°C, VDD = 2.7 V to 3.6 V
ADC Resolution 13 Bits Twos complement temperature value of sign bit plus

16 Bits Twos complement temperature value of sign bit plus

Temperature Resolution

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

Drift5 0.0073 °C 500 hour stress test at 150°C with VDD = 5.0 V
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 = 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)

Input Current ±1 µA VIN = 0 V to VDD

Input Low Voltage, VIL 0.4 V

Input High Voltage, VIH 0.7 × VDD V

Pin Capacitance 5 10 pF
DIGITAL OUTPUT (DOUT)

Output High Voltage, VOH VDD − 0.3 V I

Output Low Voltage, V

Output Capacitance, C
POWER REQUIREMENTS

Supply Voltage 2.7 5.5 V

Supply Current Peak current while converting, SPI interface inactive

1 SPS Current 1 SPS mode, TA = 25°C

1

0.0017 ±0.202 °C TA = −10°C to +85°C, VDD = 3.0 V to 3.3V
°C TA = −20°C to +105°C, VDD = 3.0 V to 3.6 V

±0.25

TA = −20°C to +85°C, VDD = 2.7 V

12 ADC bits (power-up default resolution)

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

13-Bit 0.0625 °C 13-bit resolution (sign + 12 bits)
16-Bit 0.0078 °C 16-bit resolution (sign + 15 bits)

4

OUT

OL

50 pF

OUT

±0.015 °C TA = 25°C

2 pF

= I

SOURCE

SINK

0.4 V IOL = 200 µA

= 200 µA

At 3.3 V 210 265 µA
At 5.5 V 250 300 µA

Rev. PrD | Page 4 of 26

Preliminary Technical Data ADT7320

Parameter Min Typ Max Unit Test Conditions/Comments

At 3.3 V 46 µA VDD = 3.3 V
At 5.5 V 65 µA VDD = 5.5 V

Shutdown Current Supply current in shutdown mode

At 3.3 V 2.0 15 µA

At 5.5 V 5.2 25 µA
Power Dissipation, Normal Mode 700 µW VDD = 3.3 V, normal mode at 25°C
Power Dissipation, 1 SPS Mode 150 µW Power dissipated for VDD = 3.3 V, TA = 25°C

1

Accuracy specification includes repeatability.

2

The equivalent 3 σ limits are ±0.15°C. This 3 σ specification is provided to enable comparison with other vendors who use these limits.

3

For higher accuracy at 5 V operation, contact Analog Devices, Inc.

4

Based on a floating average of 10 readings.

5

Drift includes solder heat resistance and lifetime test performed as per JEDEC Standard JESD22-A108.

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.

Parameter

t1 0 ns min

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 Bus relinquish time after CS inactive edge

7

80 ns max Bus relinquish time after CS inactive edge

t8 0 ns min SCLK inactive edge to CS rising edge hold time

t9 0 ns min

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 Error! Reference source not found..

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.

1, 2

Limit at T

MIN

, T

Unit Descriptions

MAX

CS

CS

falling edge to SCLK active edge setup time

falling edge to DOUT active time

Rev. PrD | Page 5 of 26

ADT7320 Preliminary Technical Data

DOUT

CS

t

1

t

SCLK

DIN

2

1

t

4

t

MSB LSB

t

9

5

t

3

2 3

9 10 23 24

876

t

6

MSB

Figure 2. Detailed SPI Timing Diagram

t

8

t

10

LSB

t

7

09012-002

Rev. PrD | Page 6 of 26

Preliminary Technical Data ADT7320

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

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

CS

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 Range

1

−40°C to +150°C
Storage Temperature Range −65°C to +160°C
Maximum Junction Temperature, T

150°C

JMAX

Power Dissipation2

16-Lead LFCSP3 W

MAX

= (T

− TA)/θJA

JMAX

Thermal Impedance4

θJA, Junction-to-Ambient (Still Air) 37°C/W

θJC, Junction-to-Case 33°C/W
IR Reflow Soldering 220°C
Peak Temperature (RoHS-Compliant

260°C (0°C/−5°C)

Package)
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

Sustained operation above 125°C results in a shorter product lifetime. For

more information, contact an Analog Devices, Inc., sales representative.

2

Values relate 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 resistance is more useful for air cooled, PCB­mounted 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

Rev. PrD | Page 7 of 26

ADT7320 Preliminary Technical Data

N

C

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

C

C
N

6

5

1

1

1

SCLK

2

DOUT

3

DIN

4

CS

NOTES

1. NC = NO CONNECT. DO NOT CONNECT TO THIS PIN.
THE NC PIN IS NOT BONDED TO THE DIE INTERNALLY.

2. TO ENSURE CORRECT OPERATION, THE EXPOSED PAD
SHOULD EITHER BE LEFT FLOATING OR CONNECTED
TO GROUND.

ADT7320

TOP VIEW

(Not to Scale)

6

5

C

C

N

N

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 data into and out of any register of the ADT7320.
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 control registers of the part 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 enabled when this input is low. The device is disabled when this pin is high.

5 NC No Connect. Do not connect to this pin. The NC pin is not bonded to the die internally.
6 NC No Connect. Do not connect to this pin. The NC pin is not bonded to the die internally.
7 NC No Connect. Do not connect to this pin. The NC pin is not bonded to the die internally.
8 NC No Connect. Do not connect to this pin. The NC pin is not bonded to the die internally.
9 INT Overtemperature and Undertemperature Interrupt. 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.

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

configuration. A pull-up resistor is required, typically 10 kΩ.
11 GND Analog and Digital Ground.
12 VDD Positive Supply Voltage (2.7 V to 5.5 V). Decouple the supply with a 0.1 µF ceramic capacitor to GND.
13 NC No Connect. Do not connect to this pin. The NC pin is not bonded to the die internally.
14 NC No Connect. Do not connect to this pin. The NC pin is not bonded to the die internally.
15 NC No Connect. Do not connect to this pin. The NC pin is not bonded to the die internally.
16 NC No Connect. Do not connect to this pin. The NC pin is not bonded to the die internally.
17 EPAD Exposed Pad. To ensure correct operation, the exposed pad should either be left floating or connected to ground.

C

N

N
3

4

1

1

17 EPAD

12

V

DD

11

GND

10

CT

9

INT

8

7

C

C

N

N

09012-003

Rev. PrD | Page 8 of 26