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±0.1°C Accuracy, 16-Bit, Digital I2C Temperature Sensor for VSM Applications Data Sheet ADT7422 Rev. A Document Feedback 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. Tel: 781.329.4700 ©2020 Analog Devices, Inc. All rights reserved. Technical Support www.analog.com

FEATURES

Accuracy meets clinical thermometry specification of the ASTM E1112 when soldered onto the final PCB ±0.1°C from 25°C to 50°C at 3.0 V ±0.25°C from −20°C to +105°C at 2.7 V to 3.3 V Ultralow temperature drift: 0.0073°C National Institute of Standards and Technology (NIST) traceable or equivalent Fast first temperature conversion at power-up of 6 ms Simple implementation No temperature calibration or correction required No linearity correction required Low power 140 µW typical at 3.0 V in 1 SPS mode 6 µW typical at 3.0 V in shutdown mode Programmable interrupts Critical overtemperature interrupt Overtemperature and undertemperature interrupt I2C-compatible interface 16-lead, 4 mm × 4 mm, RoHS compliant LFCSP

APPLICATIONS

Vital signs monitoring (VSM) Medical equipment Resistance temperature detector (RTD) and thermistor replacement Food transportation and storage Thermocouple cold junction compensation Environmental monitoring and heating, ventilation, and air conditioning (HVAC) Laser diode temperature control GENERAL DESCRIPTION The ADT7422 is a high accuracy, digital I2C temperature sensor designed to meet the clinical thermometry specification of the ASTM E1112 standards when soldered onto the final printed circuit board (PCB). The ADT7422 contains an internal band gap reference, a temperature sensor, and a precision analog-to-digital converter (ADC). The ADT7422 provides a 16-bit temperature result with a resolution of 0.0078°C and an accuracy of up to ±0.1°C across the temperature range of 25°C to 50°C without the need for calibration after the PCB soldering process. Operating at 3.0 V, the average supply current is typically 210 μA. The ADT7422 has a shutdown mode that powers down the device and offers a shutdown current of typically 2.0 μA at 3.0 V. The ADT7422 is rated for operation over the −40°C to +125°C temperature range. Pin A0 and Pin A1 are available for address selection and provide four possible I2C addresses for the ADT7422. 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 comparator and interrupt event modes. PRODUCT HIGHLIGHTS 1. No calibration or correction required by the user. 2. Low power consumption. 3. Long-term stability and reliability. 4. High accuracy for industrial, instrumentation, and medical applications. FUNCTIONAL BLOCK DIAGRAM INTERNAL REFERENCE

11 TEMPERATURE

Σ-Δ MODULATOR VDD GND CT INT SCL SDAI2C INTERFACE ADT7422 20961-001 Figure 1.

Rev. A | Page 2 of 23 TABLE OF CONTENTS

REVISION HISTORY

4/2020—Rev. 0 to Rev. A Changes to Data Sheet Title, Features Section, and General 1/2020—Revision 0: Initial Version

Rev. A | Page 3 of 23 SPECIFICATIONS TA = −40°C to +125°C, VDD = 2.7 V to 3.3 V, unless otherwise noted. Table 1. Parameter Symbol Min Typ Max Unit Test Conditions/Comments TEMPERATURE SENSOR AND ADC Accuracy1 ±0.12 °C TA = 25°C to 50°C, VDD = 3.0 V ±0.25 °C TA = −20°C to +105°C, VDD = 2.7 V to 3.3 V ±0.50 °C TA = −40°C to +125°C, VDD = 2.7 V to 3.3 V ADC Resolution 13 Bits Twos complement temperature value of the sign bit plus 12 ADC bits

16 Bits Twos complement temperature value of

the sign bit plus 15 ADC bit Temperature Resolution 13-Bit 0.0625 °C 13-bit resolution (sign + 12 bits) 16-Bit 0.0078125 °C 16-bit resolution (sign + 15 bits) Temperature Conversion Time 240 ms Continuous conversion and one-shot conversion modes Fast Temperature Conversion Time 6 ms First conversion on power-up only

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

Temperature Hysteresis3 ±0.002 °C Temperature cycle = 25°C to 125°C to 25°C Repeatability ±0.015 °C TA = 25°C, average of 10 readings Drift4 0.0073 °C 500-hour stress test at 150°C DC Power Supply Rejection Ratio (PSRR) 0.1 °C/V TA = 25°C DIGITAL OUTPUTS (CT, INT, SDA— OPEN-DRAIN) High Output Leakage Current IOH 0.1 5 µA CT pin and INT pin pulled up to VDD Output Low Voltage VOL 0.4 V Low output leakage current (IOL) = 1 mA at 3.3 V Output High Voltage VOH 0.7 × VDD V Output Capacitance COUT 2 pF DIGITAL INPUTS (SCL, SDA, A0, A1) Input Current ±1 µA Input voltage (VIN) = 0 V to VDD Input Low Voltage VIL 0.3 × VDD V SCL and SDA only

0.4 V A0 and A1 only

Input High Voltage VIH 0.7 × VDD V SCL and SDA only

2 V A0 and A1 only

SCL and SDA Glitch Rejection 50 ns Input filtering suppresses noise spikes of <50 ns Pin Capacitance 2 10 pF POWER REQUIREMENTS Supply Voltage 2.7 3.0 3.3 V Supply Current 210 265 µA VDD = 3.3 V while converting, I2C inactive 1 SPS Current 46 µA VDD = 3.3 V in 1 SPS mode, TA = 25°C Shutdown Current 2.0 15 µA VDD = 3.3 V Power Dissipation Normal Mode 700 µW VDD = 3.3 V, TA = 25°C Power Dissipation 1 SPS 140 µW VDD = 3.0 V, TA = 25°C Power Dissipation Shutdown Mode 6 µW VDD = 3.0 V, TA = 25°C 1 The accuracy specification includes repeatability. 2 These limits represent a 3-sigma distribution when devices are soldered to the PCB using a 16-point rolling average filter with a 300 ms sample period with the device in continuous conversion mode. 3 The temperature hysteresis specification does not include repeatability. 4 Drift includes solder heat resistance and lifetime test performed as per JEDEC Standard JESD22-A108.

(10% to 90% of VDD) and timed from a voltage level of 1.6 V. development to ensure compliance. Hold Time (Start Condition) tHD:STA 0.6 µs After this period, the first clock is generated. Setup Time (Start Condition) tSU:STA 0.6 µs Relevant for repeated start condition. Figure 2. Serial Interface Timing Diagram

TA = 25°C, unless otherwise noted. Table 4. Thermal Resistance

  1. NIC = NOT INTERNALLY CONNECTED. THE NIC PINS ARE NOT BONDED TO THE DIE INTERNALLY.
  2. EXPOSED PAD. TO ENSURE CORRECT OPERATION, EITHER LEAVE THE EXPOSED PAD

TO A PAD ON THE PCB TO CONFER MECHANICAL STRENGTH TO THE PACKAGE. Figure 3. Pin Configuration Table 5. Pin Function Descriptions and from any register of the ADT7422. A pull-up resistor of typically 10 kΩ is required. this pin. A pull-up resistor of typically 10 kΩ is required. 3 A0 I2C Serial Bus Address Selection Pin, Logic Input. Connect this pin to GND or VDD to set an I2C address. 4 A1 I2C Serial Bus Address Selection Pin, Logic Input. Connect this pin to GND or VDD to set an I2C address. 5 to 8, 13 to 16 NIC Not Internally Connected. The NIC pins are not bonded to the die internally. default setting is an active low comparator interrupt. A pull-up resistor of typically 10 kΩ is required. active low. A pull-up resistor of typically 10 kΩ is required. 11 GND Analog and Digital Ground. pad to ground. Solder the exposed pad to a pad on the PCB to confer mechanical strength to the package.

Figure 4. VSM Temperature Range of the EVAL-ADT7422MBZ Post Soldering Figure 5. Narrow Temperature Range of the EVAL-ADT7422MBZ Post Figure 6. Wide Temperature Range of the EVAL-ADT7422MBZ Post Soldering Figure 7. Standard Deviation of the EVAL-ADT7422MBZ Post Soldering to Figure 8. Histogram Distribution of Factory Calibration Error at 38°C for

170 Devices, VDD = 3 V

Figure 9. Factory Calibration Error at 38°C for 170 Devices, VDD = 3 V

digital modulator (see Figure 13). deliver 16 bits of resolution in a compact circuit. 1VPTAT IS A VOLTAGE PROPORTIONAL TO ABSOLUTE TEMPERATURE. Figure 13. Σ-Δ Modulator low. Fast conversion temperature accuracy is typically within ±5°C. The conversion clock for the device is generated internally. via the configuration register (Register Address 0x03). conversion and then goes into shutdown mode. time to power up and complete a conversion. Bit 5 to 1 in the configuration register (Register Address 0x03).

MSB being the temperature sign bit. Address 0x09 (TCRIT setpoint least significant byte register). The default setting for the TCRIT setpoint register is 147°C. Table 6. THIGH Setpoint Most Significant Byte Register (Register Address 0x04) [15:8] 0x20 R/W THIGH most significant byte MSBs of the overtemperature limit, stored in twos complement format. Table 7. THIGH Setpoint Least Significant Byte Register (Register Address 0x05) [7:0] 0x00 R/W THIGH least significant byte LSBs of the overtemperature limit, stored in twos complement format. Table 8. TLOW Setpoint Most Significant Byte Register (Register Address 0x06) [15:8] 0x05 R/W TLOW most significant byte MSBs of the undertemperature limit, stored in twos complement format. Table 9. TLOW Setpoint Least Significant Byte Register (Register Address 0x07) [7:0] 0x00 R/W TLOW least significant byte LSBs of the undertemperature limit, stored in twos complement format. Table 10. TCRIT Setpoint Most Significant Byte Register (Register Address 0x08) [15:8] 0x49 R/W TCRIT most significant byte MSBs of the critical overtemperature limit, stored in twos complement format. Table 11. TCRIT Setpoint Least Significant Byte Register (Register Address 0x09) [7:0] 0x80 R/W TCRIT least significant byte LSBs of the critical overtemperature limit, stored in twos complement format.

register resets the INT pin and CT pin. (Register Address 0x03, Bits[6:5]) resets the INT pin. Bits[6:5]) resets the CT pin (see Figure 14). rate is used for the given application.

1 SPS MODE

In 1 SPS mode, the device performs one measurement per second. read from the ADT7422 when the device is in shutdown mode. clock starts and a conversion is initiated. does not, the fault count is reset back to zero. 60ms IN THE CASE OF A ONE SHOT CONVERSION. Figure 14. One Shot CT Pin

register are represented by a 13-bit twos complement word. 13-bit temperature data format without Bits[2:0]. has a 13-bit temperature data value. Table 12. 13-Bit Temperature Data Format where Bit 15 (sign bit) is removed from the ADC code. where Bit 15 (sign bit) is removed from the ADC code. where Bit 9 (sign bit) is removed from the ADC code. where Bit 8 (sign bit) is removed from the ADC code.

  • Nine temperature registers
  • One status register
  • One ID register
  • One configuration register
  • One address pointer register
  • One software reset All registers are 8 bits wide. The temperature value registers, the status register, and the ID register are read only. The software reset register is a write only register. At power-up, the address pointer register is loaded with 0x00 and points to the temperature value most significant byte register (Register Address 0x00) (see Table 13).

Table 13. Registers Table 14. Address Pointer Register least significant byte can be read within the same transaction. bits and are used as the LSBs for the extended digital value instead. Table 15. Temperature Value Most Significant Byte Register (Register Address 0x00) Table 16. Temperature Value Least Significant Byte Register (Register Address 0x01) 0 0 R TLOW flag/LSB0 Flags a TLOW event if the configuration register, Register Address 0x03, Bit 7 = 0 (13-bit resolution). When the temperature value is below TLOW, this bit is set to 1. Register Address 0x03, Bit 7 = 1 (16-bit resolution). 1 0 R THIGH flag/LSB1 Flags a THIGH event if the configuration register, Register Address 0x03, Bit 7 = 0 (13-bit resolution). When the temperature value is above THIGH, this bit is set to 1. Register Address 0x03, Bit 7 = 1 (16-bit resolution). 2 0 R TCRIT flag/LSB2 Flags a TCRIT event if the configuration register, Register Address 0x03, Bit 7 = 0 (13-bit resolution). When the temperature value exceeds TCRIT, this bit is set to 1. Register Address 0x03, Bit 7 = 1 (16-bit resolution). [7:3] 00000 R Temp Temperature value in twos complement format.

also reflects the status of a temperature conversion operation. the operation mode bits in the configuration register. Table 17. Status Register (Register Address 0x02) [3:0] 0000 R Unused Reads back 0. setpoint TLOW + THYST registers. setpoint THIGH − THYST registers. setpoint TCRIT − THYST registers. a write to the operation mode bits in the configuration register. Table 18. Configuration Register (Register Address 0x03) setting the INT pin and CT pin. This helps to avoid false triggering due to temperature noise. 2 0 R/W CT pin polarity This bit selects the output polarity of the CT pin. 3 0 R/W INT pin polarity This bit selects the output polarity of the INT pin. 4 0 R/W INT/CT mode This bit selects between comparator mode and interrupt mode. [6:5] 00 R/W Operation mode These two bits set the operational mode for the ADT7422. 00 = continuous conversion (default). When one conversion is finished, the ADT7422 starts another. 01 = one shot. Conversion time is typically 240 ms. 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.

The default setting for the THIGH setpoint register is 64°C. MSB being the temperature sign bit. Address 0x07 (TLOW setpoint least significant byte register). The default setting for the TLOW setpoint register is 10°C. setting for the ID register is 0xCB. Table 19. THYST Setpoint Register (Register Address 0x0A) [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 Not applicable Not used. Table 20. ID Register (Register Address 0x0B) [2:0] 011 R Revision ID Contains the silicon revision identification number. [7:3] 11001 R Manufacture ID Contains the manufacture identification number.

contents of the temperature value register is shown in Figure 19. address to the least significant byte register address. address pointer register to set up the relevant register address. operation to set up the register address again. Figure 18. Reading Back Data from the Configuration Register

  1. A START CONDITION AT THE BEGINNING IS DEFINED AS A HIGH TO LOW TRANSITION ON SDA WHILE SCL REMAINS HIGH.
  2. A STOP CONDITION AT THE END IS DEFINED AS A LOW TO HIGH TRANSITION ON SDA WHILE SCL REMAINS HIGH.
  3. THE MASTER GENERATES THE NO ACKNOWLEDGE AT THE END OF THE READBACK TO SIGNAL THAT IT DOES NOT WANT ADDITIONAL DATA.
  4. TEMPERATURE VALUE REGISTER MSB DATA AND TEMPERATURE VALUE REGISTER LSB DATA ARE ALWAYS SEPARATED BY A LOW ACK BIT.
  5. THE R/W BIT IS SET TO A1 TO INDICATE A READBACK OPERATION.

1 A1 A0

0 A1 A0

01 A1 A0 R/W

Figure 19. Reading Back Data from the Temperature Value Register

Rev. A | Page 19 of 23 RESET To reset the ADT7422 without having to reset the entire I2C bus, an explicit reset command is provided. This command uses a particular address pointer word as a command word to reset the device and upload all default settings. The ADT7422 does not respond to (does not acknowledge) the I2C bus commands while the default values upload for approximately 200 µs. Use the following sequence to perform a reset: 1. Write to the ADT7422 using the appropriate address. 2. Read the acknowledge bit. 3. Set the register address to 0x2F. 4. Read the acknowledge bit. 5. Apply stop condition. 6. Wait 200 µs for the device to reset the registers to the default power-up settings. GENERAL CALL When a master issues a slave address consisting of seven 0s with the 8th bit (R/W bit) set to 0, the address is known as the general call address. The general call address is for addressing every device connected to the I2C bus. The ADT7422 acknowledges this address and reads in the following data byte. If the second byte is 0x06, the ADT7422 resets completely and uploads all default values. The ADT7422 does not respond to (does not acknowledge) the I2C bus commands while the default values upload for approximately 200 µs. The ADT7422 does not acknowledge any other general call commands.

Figure 21. INT Output Temperature Response Diagram for TLOW Undertemperature Events

COMPLIANT TO JEDEC STANDARDS MO-220-WGGC.

0.05 MAX

0.02 NOM

0.20 REF

0.20 MIN

Figure 23. 16-Lead Lead Frame Chip Scale Package [LFCSP] registered trad emarks are the property of their res pective owners.