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±0.25°C Accurate, 16-Bit Digital

SPI Temperature Sensor

Data Sheet

ADT7320

Rev. 0 Document Feedback

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FEATURES

High performance

Temperature accuracy

±0.20°C from −10°C to +85°C at 3.0 V

±0.25°C from −20°C to +105°C at 2.7 V to 3.3 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

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

GENERAL DESCRIPTION

The ADT7320 is a high accuracy digital temperature sensor that

offers 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

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

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.

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.

FUNCTIONAL BLOCK DIAGRAM

INTERNAL

REFERENCE

TEMPERATURE

SENSOR

HIGH

CRIT

LOW

INTERNAL

OSCILLATOR

FILTER

LOGIC

Σ-Δ

MODULATOR

GND

INT

ADT7320

TEMPERATURE

VALUE

CONFIGURATION

HYST

LOW

HIGH

CRIT

STATUS

SCLK

DOUT

DIN

SPI

INTERFACE

09012-001

Figure 1.

Summary of content (24 pages)

PAGE 1
±0.25°C Accurate, 16-Bit Digital SPI Temperature Sensor ADT7320 Data Sheet FEATURES GENERAL DESCRIPTION High performance Temperature accuracy ±0.20°C from −10°C to +85°C at 3.0 V ±0.25°C from −20°C to +105°C at 2.7 V to 3.3 V 16-bit temperature resolution: 0.0078°C Ultralow temperature drift: 0.
PAGE 2
ADT7320 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Configuration Register .............................................................. 14 Applications ....................................................................................... 1 Temperature Value Register ...................................................... 15 General Description ..................................................................
PAGE 3
Data Sheet ADT7320 SPECIFICATIONS TA = −40°C to +125°C, VDD = 2.7 V to 5.5 V, unless otherwise noted. Table 1.
PAGE 4
ADT7320 Data Sheet Parameter Shutdown Current At 3.3 V At 5.5 V Power Dissipation, Normal Mode Power Dissipation, 1 SPS Mode Min Typ Max Unit 2.0 5.2 700 150 15 25 µA µA µW µW Test Conditions/Comments Supply current in shutdown mode VDD = 3.3 V, normal mode at 25°C Power dissipated for VDD = 3.3 V, TA = 25°C Accuracy specification includes repeatability. 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.
PAGE 5
Data Sheet ADT7320 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.
PAGE 6
ADT7320 Data Sheet 13 NC 14 NC 15 NC 16 NC PIN CONFIGURATION AND FUNCTION DESCRIPTIONS 17 EPAD SCLK 1 12 VDD ADT7320 DOUT 2 10 CT 9 INT NC 8 NC 7 NC 6 NC 5 CS 4 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. 09012-003 DIN 3 11 GND TOP VIEW (Not to Scale) Figure 3. Pin Configuration Table 4. Pin Function Descriptions Pin No.
PAGE 7
Data Sheet ADT7320 TYPICAL PERFORMANCE CHARACTERISTICS 30 1.00 25 0.50 SHUTDOWN IDD (µA) MAX ACCURACY LIMITS 0.25 0 –0.25 MAX ACCURACY LIMITS 20 15 10 5.0V 4.5V 3.3V 3.0V 2.7V 3.6V –40 –20 0 20 40 60 80 TEMPERATURE (°C) 100 120 140 0 –100 09012-027 –1.00 –60 –50 0 50 100 150 200 TEMPERATURE (°C) 09012-032 5 –0.75 Figure 7. Shutdown Current vs. Temperature Figure 4. Temperature Accuracy at 3 V 300 1.00 0.75 0.50 CONTINUOUS CONVERSION 250 MAX ACCURACY LIMITS 200 0.
PAGE 8
ADT7320 Data Sheet 140 125°C 120 85°C 80 IT TAKES LESS THAN 2 SECONDS FOR THE DUT TO REACH 63.2% OF ITS FINAL TEMPERATURE SPAN 60 40 20 0 0 5 10 15 TIME (s) 20 25 09012-110 DUT TEMPERATURE (°C) 105°C 100 Figure 10. Thermal Response Time Rev.
PAGE 9
Data Sheet ADT7320 THEORY OF OPERATION CIRCUIT INFORMATION The ADT7320 is a high accuracy digital temperature sensor that uses a 16-bit ADC to monitor and digitize the temperature to a resolution of 0.0078°C. By default, the ADC resolution is set to 13 bits (0.0625°C). An internal temperature sensor generates a voltage proportional to absolute temperature; this voltage is compared to an internal voltage reference and input into a precision digital modulator.
PAGE 10
ADT7320 Data Sheet CS 0x08 DIN 0x20 WAIT 240ms MINIMUM FOR CONVERSION TO FINISH DATA 09012-300 DOUT SCLK Figure 12. Typical SPI One-Shot Write to Configuration Register Followed by a Read from the Temperature Value Register 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.
PAGE 11
Data Sheet ADT7320 1 SPS MODE FAULT QUEUE In 1 SPS mode, the part performs one measurement per second. A conversion takes 60 ms typically, and the part remains in the idle state for the remaining 940 ms period. This mode is enabled by setting Bits[6:5] of the configuration register (Register Address 0x01) to 10. Bit 0 and Bit 1 of the configuration register (Register Address 0x01) are used to set up a fault queue.
PAGE 12
ADT7320 Data Sheet TEMPERATURE DATA FORMAT TEMPERATURE CONVERSION FORMULAS One LSB of the ADC corresponds to 0.0625°C in 13-bit mode or 0.0078°C in 16-bit mode. The ADC can theoretically measure a temperature range of 255°C, but the ADT7320 is guaranteed to measure a low value temperature limit of −40°C to a high value temperature limit of +150°C.
PAGE 13
Data Sheet ADT7320 REGISTERS STATUS REGISTER The ADT7320 contains eight registers: • • • • 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.
PAGE 14
ADT7320 Data Sheet CONFIGURATION REGISTER This 8-bit read/write register (Register Address 0x01) stores various configuration modes for the ADT7320, including shutdown, overtemperature and undertemperature interrupts, one-shot, continuous conversion, interrupt pin polarity, and overtemperature fault queues. Table 8.
PAGE 15
Data Sheet ADT7320 TEMPERATURE VALUE REGISTER ID REGISTER The temperature value register stores the temperature measured by the internal temperature sensor. The temperature is stored in 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 (Register Address 0x03) stores the manufacturer ID in Bit 7 to Bit 3 and the silicon revision in Bit 2 to Bit 0.
PAGE 16
ADT7320 Data Sheet THYST SETPOINT REGISTER TLOW SETPOINT REGISTER The 8-bit THYST setpoint 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 the 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.
PAGE 17
Data Sheet ADT7320 SERIAL INTERFACE PULL-UP TO VDD VDD VDD ADT7320 SCLK DOUT DIN CS 10kΩ GND CT INT 09012-014 MICROCONTROLLER 10kΩ 0.1µF Figure 14. Typical SPI Interface Connection The ADT7320 has a 4-wire serial peripheral interface (SPI). The interface has a data input pin (DIN) for writing data to the device, a data output pin (DOUT) for reading data back from the device, and a serial data clock pin (SCLK) for clocking data into and out of the device.
PAGE 18
ADT7320 Data Sheet Figure 15 shows a write to an 8-bit register, and Figure 16 shows a write to a 16-bit register. WRITING DATA Data is written to the ADT7320 in 8 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 ADT7320 clocks the data into the register addressed in the command byte on the rising edge of SCLK.
PAGE 19
Data Sheet ADT7320 CS SCLK 2 1 4 3 5 7 6 9 8 11 10 12 13 14 16 15 8-BIT COMMAND BYTE DIN 0 R/W C7 C6 REGISTER ADDR C5 C4 C3 0 0 0 C2 C1 C0 D7 D6 D5 D4 D3 D2 15 16 17 D1 09012-030 8-BIT DATA DOUT D0 Figure 17.
PAGE 20
ADT7320 Data Sheet 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. The ADT7320 must be fully powered up to VDD before reading INT and CT data. 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.
PAGE 21
Data Sheet ADT7320 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 Figure 20. INT Output Temperature Response for TLOW Undertemperature Events Rev.
PAGE 22
ADT7320 Data Sheet APPLICATIONS INFORMATION THERMAL RESPONSE TIME POWERING FROM A SWITCHING REGULATOR 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 that the IC is mounted to. For example, a large PCB containing large amounts of copper tracing can act as a large heat sink and slow the thermal response.
PAGE 23
Data Sheet ADT7320 OUTLINE DIMENSIONS PIN 1 INDICATOR 4.10 4.00 SQ 3.90 0.35 0.30 0.25 0.65 BSC 16 13 PIN 1 INDICATOR 12 1 EXPOSED PAD 4 2.70 2.60 SQ 2.50 9 0.80 0.75 0.70 0.45 0.40 0.35 8 0.05 MAX 0.02 NOM COPLANARITY 0.08 0.20 REF SEATING PLANE 5 BOTTOM VIEW 0.20 MIN FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET. COMPLIANT TO JEDEC STANDARDS MO-220-WGGC. 08-16-2010-C TOP VIEW Figure 22.