Surface Temp 2 Click Board

How Does The Surface Temp 2 Click Board™ Work?

The Surface Temp 2 Click Board™ is based on the ADT7422, a high accuracy 16-bit digital temperature sensor with programmable interrupt and critical temperature indicator from Analog Devices. The ADT7422 has high accuracy and linearity over the entire rated temperature range without needing correction or calibration by the user. Operating at 3.3 V, the average supply current is typically 210 μA. The ADT7420 has a shutdown mode that powers down the device and offers a shutdown current of typically 2.0 μA at 3.3 V. The ADT7422 Digital Temperature Sensor is designed to meet the ASTM E1112 standard of clinical thermometry specification. This sensor is used in applications such as Vital Signs Monitoring (VSM), medical equipment, thermocouple cold junction compensation, and laser diode temperature control.

The Surface Temp 2 Click Board™ has a sensing pad, which is thermally connected to an ADT7422, for temperature sensing. It 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 compared to an internal voltage reference and input into a precision digital modulator. The sensor output is digitized by a Σ-Δ modulator, also known as the charge balance type ADC. This type of converter utilizes time-domain oversampling and a high accuracy comparator to deliver 16 bits of resolution.

The Surface Temp 2 Click Board™ communicates with MCU using the standard I2C 2-Wire interface with a maximum frequency of 400kHz. The ADT7422 has a 7-bit slave address with the first five MSBs fixed to 10010. The address pins A0 and A1 are programmed by the user and determines the value of the last two LSBs of the slave address which can be selected by onboard SMD jumpers labelled as ADDR SEL allowing selection of the slave address LSBs.

It also generates a programmable interrupt signal (over/under temperature indicator) routed on the INT pin and critical overtemperature indicator CT routed on the PWM pin of the mikroBUS™ socket. Those pins have two over/under temperature modes: Comparator and Interrupt mode. The Interrupt mode is the default overtemperature mode which sets INT pin high when the temperature is greater than the internally defined limit value, while in Comparator mode the INT pin returns to an inactive state when the temperature drops below that limit value. The CT pin is activated if a critical overtemperature event occurs.

The Surface Temp 2 Click Board™ is designed to be operated with both 3.3V and 5V logic voltage levels that can be selected via VCC SEL jumper. This allows for both 3.3V and 5V capable MCUs to use the I2C communication lines properly.

SPECIFICATIONS

PINOUT DIAGRAM

This table shows how the pinout of the Surface Temp 2 Click Board™ corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
NC	1	AN	PWM	16	CT	Critical Overtemp Indicator
NC	2	RST	INT	15	INT	Overtemp and Undertemp Indicator
NC	3	CS	RX	14	NC
NC	4	SCK	TX	13	NC
NC	5	MISO	SCL	12	SCL	I2C Clock
NC	6	MOSI	SDA	11	SDA	I2C Data
Power Supply	3.3V	7	3.3V	5V	10	5V	Power Supply
Ground	GND	8	GND	GND	9	GND	Ground

ONBOARD SETTINGS AND INDICATORS

SURFACE TEMP 2 CLICK ELECTRICAL SPECIFICATIONS