ams Unveils Family of Digital Temperature Sensors for Tight Thermal Control

November 12, 2019 by Gary Elinoff

Sized at only 1.5 mm2, members of the AS621x family offer a range of temperature accuracies for design flexibility.

ams has announced the AS621x family of digital temperature sensors, which requires 6 µAmps of current when making four measurements per second. The new family also features a standby requirement of only 0.1 µAmps. The tiny devices are available in 1.5 mm2 wafer-level, chip-scale packages (WLCSP) for easy integration into any design.


Block diagram of the AS621x family of temperature sensors

Block diagram of the AS621x family of temperature sensors. Image from ams


"We are making thermal management easy for our customers as the family’s ultra-low power consumption—in addition to its tiny size—enables a tight thermal control,” says Michael Leitner, Vice President and General Manager for the business line of medical and specialty sensors at ams.


Design Specifications

These devices can operate from a supply voltage ranging from 1.71V to 3.6V and operate over a temperature range of -40 to +125 °C. They can also make a reading of temperature in as little 32 milliseconds. 

All three temperature sensors can be programmed to deliver an alert if the measured temperature goes above or below a given range.


A Single I2C Bus

The units are controlled through the industry-standard I2C bus, and the user can choose from eight separate I2C addresses. This allows the designer to control eight separate AS621x sensors through one I2C bus.


Temperature Accuracy

The three members of the AS621x family differ in terms of the accuracy they offer:


AS621x family's differing temperature accuracies

The AS621x family differs in temperature accuracy.

Because of the varying levels of accuracy that each member of the family affords, designers have the flexibility to pay for the level of accuracy needed for the proper operation of their designs. 


Applications for Battery-operated Devices

Leitner claims that “The new AS621x family of temperature sensors from ams is ideally suited for battery-operated devices, including wearables, laptops, and tablets."

In addition to wearables, laptops, and tablets, these temperature sensors can also be used in industrial automation, mobile health monitors, and solid-state disks.


Demo Kit for the AS621x Family

Users can access the AS621x demo kit from a Bluetooth-enabled app available from the iOS App Store or Google Play Store.


Demo kit app for AS621x

Demo kit app for AS621x. Image from ams

Using this app, designers can easily modify all settings of the sensor and observe the impact—not only on power consumption but also on the effect of the temperature conversion rates.

The app also provides basic information about the AS621x family and helps demonstrate the principals of the alert mode. 


Evaluation Kit for AS621x Family

Built on a PCB, the AS621x Eval Kit simplifies the evaluation of the three family members. The unit features an AS621x digital temperature sensor, pull-up resistors, and a decoupling capacitor. 


The AS621x Eval Kit

Evaluation kit for the AS621x family. Image from ams


The eight I²C addresses of the sensor can be readily set using a handy set of jumpers included in the kit. To connect the evaluation kit to the application processor, a 5x1 pin header with a 2.54mm pitch is included.


Around the Industry

The AS621x family compares to several other digital temperature sensors in the industry.

Texas Instruments offers the TMP117, a digital temperature sensor with integrated non-volatile memory and a temperature range of -55 °C to 150 °C. It also sports an accuracy of ±0.3 °C or better. This digital temperature sensor meets the ASTM E1112 and ISO 80601 standards required of electronic patient thermometers. 

ST also offers its STTS751 digital temperature sensor. Communication is effected using a bus compatible with the 2-wire SMBus 2.0 bus. Temperature resolution can be configured to between 9 and 12 bits by the user. At 10 bits, the conversion time is 21 milliseconds and temperature resolution is within ±0.25 °C.



What do you look for in a digital temperature sensor? Let us know in the comments below.