New-Tech Europe Magazine | February 2019

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capability that allows multi-year lifetime from a small
primary battery.
The STEVAL-FKI001V1 development kit is available
now from ST distributors, or directly through ,
priced $56.00.
ams introduces world’s smallest 1D
time-of-flight sensor for accurate proximity
sensing and distance measurement in
smartphones
ams, a leading worldwide supplier of high performance
sensor solutions, introduces the world’s smallest
integrated 1D time-of-flight distance measurement and
proximity sensing module.
The sensor is ideal for implementing presence
detection, for example to trigger the operation of a
facial recognition system when the user’s face is in
range. Supplied in a 2.2mm x 3.6mm x 1.0mm package,
the new TMF8701 sensor fits in a narrow bezel, helping
smartphone manufacturers to realize widescreen phone
designs that have a high display screen to body ratio.
“Smartphone manufacturers have been clear about
the drawbacks of today’s 1D time-of-flight sensors:
they are too large, and their performance degrades
noticeably in adverse lighting conditions and when the
display screen is dirty,” said Dave Moon, Senior Product
Marketing Manager in the Integrated Optical Sensors
business line of ams. “The TMF8701 addresses all of
these concerns, providing customers with a device in a
smaller footprint which also offers exceptional rejection
of contamination and interference.”
The TMF8701 integrates a VCSEL infrared emitter,
multiple SPAD (single photon avalanche photodiode)
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 TMF8701 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 has excellent
immunity to interference from ambient light and
produces accurate distance measurement in all lighting
conditions: the module achieves accuracy of ±5% when
measuring distance in the range 20-60cm in normal
lighting conditions. Even in bright sunlight (100klux),
±5% accuracy is maintained at a range of up to 35cm.
The low-power operation of the TMF8701 – it draws
only 940µA in proximity sensing mode when sampling at
10Hz – makes it the ideal companion to a smartphone’s
face recognition system. 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
60cm from the display screen.
The proximity sensing capability 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 0-10cm 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 in an order quantity of 5,000
units.
An evaluation kit for the TMF8701 is available. For
sample requests and more technical information, go to
New-Tech Magazine Europe l 79