Tiny dToF Module Provides Accurate Distance Measurement for Robotics and SmartphonesSeptember 25, 2019 by Paul Shepard
ams announced the release of what is thought to be the world’s smallest integrated module for direct time-of-flight (dToF) distance measurement providing accurate measurements from 2cm up to 2.5m. The TMF8801 is more than 30% smaller than competing ToF sensors – making it perfect for compact space constrained designs – yet offers superior performance in important parameters including accuracy and usability in the presence of sunlight.
According to ams, competing ToF sensors struggle to accurately measure distance below dirty or smudged cover glass whereas the TMF8801 maintains high accuracy through use of its on-chip histogram processing.
“The new TMF8801 direct ToF sensor which complements the TMF8701 short range ToF sensor released in 2018, provides extended distance range sensing for smartphones,” says Dave Moon, Senior Product Marketing Manager in the Integrated Optical Sensors business line at ams.
“The TMF8801 is ideally suited to provide support for improving world-facing mobile phone camera performance using laser detection auto-focus (LDAF), enabling mobile phone users to take pin-sharp photos and selfies,” Moon added.
- Direct ToF technology with high sensitivity SPAD detection
- Fast Time-to-Digital Converter (TDC) architecture
- Sub-nanosecond light pulse
- 20- to 2,500-mm distance sensing @ 30Hz
- On-chip histogram processing
- 940nm VCSEL Class 1 Eye Safety
- Sunlight on-chip rejection filter and algorithm
- Industry’s smallest modular OLGA 2.2 x 3.6 x 1.0 mm package
- Delivers high SNR, wide dynamic range and no multi-path reflections
- Enables dark and sunlight environment distance measurement within ±5%
- Provides best-in-class resolution ranging mode detection sensing
- Enables accurate distance measurements
- Provides high accuracy, greater distance between cover glass, dynamic cover glass calibration, dirt or smudge removal and crosstalk compensation
- Eye-safety circuitry stops VCSEL driver if VCSEL fault occurs
- Optical filters with algorithm support enables high ambient light resilience
- Reduce board space requirements, enables low-profile system designs in restricted space industrial designs
How is this industry-leading accuracy achieved?
With an integrated VCSEL infrared emitter, multiple SPAD (single photon avalanche photo-diode) light detectors, time-to-digital converter, and on-chip microcontroller for processing histograms, the TMF8801 delivers superior ToF performance. Compared to distance averaging employed with an indirect ToF system, the direct ToF time measurement methodology used in the TMF8801 delivers higher accuracy true-distance measurements.
When used to support LDAF, high accuracy distance measurements deliver improved camera performance: sharper, in-focused images under any ambient lighting conditions, and accurate adjustment of the camera flash brightness to improve picture quality.
Not just for smartphones – further applications
The small size and low power consumption of the TMF8801 is ideal for fast-ranging collision avoidance detection used in autonomous vacuum cleaners, and industrial robotics. For display-based products such as mobile computing, the TMF8801 can be used for user presence detection to automatically wake up or put the system into a low-power sleep mode based on the presence or absence of a user.
The TMF8801 is housed in a 2.2mm x 3.6mm x 1.0mm package and is in volume production. Unit pricing is $2.89 in order quantities of 5,000 pieces.