Promoted as the world’s smallest integrated 1D time-of-flight distance measurement and proximity sensor, the TMF8701 from ams comes in a 2.2 mm x 3.6 mm x 1 mm package. Initial attributes include excellent smudge and dirt rejection, high immunity to interference from ambient light, and tightly-controlled field of view.
The TMF8701 integrates a VCSEL infrared emitter, multiple single-photon avalanche-photodiode (SPAD) light detectors, time-to-digital converter, and a histogram processing core. The device implements all histogram-based presence detection, distance measurement and proximity sensing algorithms on-chip.
The component separately identifies reflections from fingerprint smudge contaminations on the display screen and optical reflections from objects beyond the cover glass, such as the user’s face, maintaining reliable performance even when the sensor’s aperture is dirty. The Class 1 Eye Safe VCSEL emitter exhibits reliable immunity to interference from ambient light and produces accurate distance measurement in all lighting conditions. The component achieves an accuracy of ±5% when measuring distance in the range 20 cm to 60 cm in normal lighting conditions. Even in bright sunlight (100 klux), ±5% accuracy is maintained at a range of up to 35 cm.
The TMF8701 draws 940 µA in proximity sensing mode when sampling at 10 Hz. Always on, it triggers the higher-power face recognition system to start up when the ToF sensor detects the presence of an object up to 60 cm from the display screen. Proximity sensing capabilities of the device can also be used to trigger the display and face recognition system to switch off when detecting a reflective surface at a distance of 0 to 10 cm from the screen.
The accuracy of the TMF8701’s distance measurements also supports the selfie camera’s LDAF (laser detect auto-focus) function, especially in low-light conditions. The TMF8701 time-of-flight sensor is in mass production now. Unit pricing is $2.60 each/5,000. For more enlightenment, checkout the TMF8701 datasheet.