Sep 10 2020 6 mins 11
This week's EYE on NPI brings you Analog Devices' ADT7422 ultra-high accuracy and precision temperature sensor. (https://www.digikey.com/en/product-highlight/a/analog-devices/adt7422-01-c-accurate-digital-temperature-sensor) With an astonishing ±0.1°C rated accuracy, you can use this sensor for real-time, calibration-free temperature sensing. A built-in I2C ADC interface provides 16-bit data, so you could use this sensor with any microcontroller or microprocessor and get 0.0078 °C resolution. And you can have up to 4 of these sensors on a single I2C bus by changing the I2C address pins A0/A1. ADT7422 is ADI's first ±0.1°C accurate temperature sensor that doesn't require any external circuitry for operation. It can easily replace more complex and expensive solutions that use alternative sensor technologies such as thermistors or RTDs. In addition, high-precision silicon sensors (ICs) are preferred options for a range of emerging applications in the healthcare market such as vital signs monitoring instruments for clinical and home use. Features ±0.1°C accuracy specification enables the end product to measure temperature with accuracy that was only possible for thermistors and RTDs Doesn't require external circuitry: smaller, lower power, and lower cost than older sensing technologies Fully tested and calibrated solution: doesn't require system calibration to achieve desired ±0.1°C measurement precision The highest accuracy of ±0.1°C comes is achievable between 25°C ~ 50°C. From −20°C to +105°C the accuracy is ±0.25°C and from −40°C to +125°C its ±0.50°C. For high temperature ranges, such as for use with scientific or food processes, you probably want to go with a PT100/PT1000 RTD sensor interface (https://www.analog.com/en/applications/technology/precision-sensor-interface/temperature-sensing/rtd.html) - for example verifying the temperature of a yogurt processing system, or a chemical heater. These sensors are more tuned towards human/bio measurement - for example a long-term temperature/health monitor that uses skin temperature, implanted glucose monitor, or an incubator - all places where you want very high accuracy! Interfacing with the chip is really simple, in fact we were able to borrow a lot of code from the ADT7410 (https://www.adafruit.com/product/4089) library we wrote a year ago (https://github.com/adafruit?q=adt7410&type=&language=) and read out the temperature in both C and Python. Analog Devices also has 'pure C' drivers available on GitHub (https://github.com/analogdevicesinc/no-OS/tree/master/drivers/temperature/adt7420) We picked up one of Analog Device's dev boards. You can see a few interesting details like PCB slots to help keep the chip thermally isolated. There's also an Arduino-compatible Eval shield (https://www.analog.com/media/en/dsp-documentation/evaluation-kit-manuals/dc2026cfe.pdf) you can use to plug and play this sensor, but we found it works perfectly fine with plain 0.1" jumpers, just make sure you're giving it 3.3V for power! Add tiny, accurate temperature sensing today by picking up an ADT7422 from Digi-Key, available in cut-tape & reel, by visiting https://www.digikey.com/short/zf0d21 Your order will ship same day and you can get it in hand the next morning!
