TMF8701 sensor, excellent stain and contamination resistance
High tolerance to ambient light interference and excellent field of view

On the 9th, ams launched the integrated 1D ToF (time-of-flight) distance measurement and proximity sensing module 'TMF8701'.
The new sensor is ideal for implementing presence detection functionality. It can be used to implement applications that trigger facial recognition systems when a smartphone user's face enters a specified range.

Packaged in a 2.2mm x 3.6mm x 1.0mm package, the TMF8701 is ideal for narrow bezels, enabling smartphone manufacturers to implement widescreen device designs with high screen-to-body ratios (SBRs).

The TMF8701 integrates a VCSEL infrared emitter, multiple single photon avalanche photodiode (SPAD) photodetectors, a time-to-digital converter (TDC), and a histogram processing core. It has built-in functions such as histogram-based object detection, distance measurement, and proximity sensing algorithms.

The ams TMF8701 distinguishes between reflections from fingerprint smudges on a display screen and optical reflections from objects above the cover glass, such as a user's face, so it maintains reliable performance even when the sensor's aperture becomes dirty.

This Class 1 Eye Safe VCSEL emitter exhibits excellent immunity to interference from ambient light and provides accurate distance measurement performance in all lighting conditions.

It achieves a high accuracy of ±5% when measuring distances between 20 and 60 cm under normal lighting conditions. Even in bright sunlight (100 klux), it maintains an accuracy of ±5% for distances up to 35 cm.

The TMF8701 is characterized by low power consumption. The new device consumes only 940µA of current when performing proximity sensing operations at a sampling rate of 10Hz, making it ideal for use in facial recognition systems in smartphones.

In always-on mode, the high-power facial recognition system can be triggered when the ToF sensor detects an object within a range of up to 60 cm from the display screen.

Because of its excellent proximity sensing capability, it can also be used for switching functions in display and facial recognition systems when it detects the reflection of an object's surface at a distance of 0 to 10 cm from the screen.

The TMF8701 can support the selfie camera's LDAF (laser detect auto-focus) function based on its high-accuracy distance measurement performance, and this performance is especially effective in low-light environments.

The TMF8701 ToF sensor is now in production, priced at $2.60 in quantities of 5,000. An evaluation kit for the TMF8701 is available from the ams ICdirect online shop.

“Smartphone manufacturers are acutely aware of the drawbacks of 1D FoT sensors,” said Dave Moon, Senior Product Marketing Manager in the Integrated Optical Sensors business line at ams. “They are too large, and their performance degrades noticeably in backlit situations or when the display screen is dirty.”

“The TMF8701 addresses all concerns related to the shortcomings of 1D FoT sensors by being a smaller footprint device that significantly reduces concerns about contamination and interference,” he continued.