Synaptics’ 4-in-1 Sensor Fusion Processor Ushers in Era of Intuitive IoT Applications

Article By : Synaptics Inc.

The FlexSense sensor processors capture and intelligently handle input from up to four sensors in a tiny, ultra-low-power form factor.

Integrating a mix of capacitive, inductive, Hall effect and ambient sensing into a single processor with proprietary algorithms, the FlexSense family brings reliable, low-latency, and context-aware force, proximity, and touch sensing to Internet of things (IoT) devices such as true wireless stereo (TWS) earbuds, gaming controllers, augmented reality (AR) and virtual reality (VR) headsets, fitness bands, remote controls, and smart thermostats.

“Today’s IoT devices are using multiple sensors to create richer interactions with users, but discrete implementations consume too much space and power, complicate system design and component supply chains, and don’t respond appropriately to false activations,” said Mahesh Srinivasan, VP, Smart Sensing and Display at Synaptics. “By intelligently fusing multiple sensors in a single processor with proprietary algorithms, we enable more robust and reliable solutions for IoT applications that allow more intuitive and responsive interactions—while reducing system design, cost, configuration, and supply chain complexity for our customers.”

FlexSense incorporates a central microcontroller that connects to two proprietary low-power, extremely fast analog front end (AFE) engines. These AFE engines quickly and efficiently sense and digitize data from the capacitive and inductive elements on the touch surfaces of an IoT product. The Hall effect sensors are implemented via metal plates on the device that detect magnetic fields, while an on-chip temperature sensor measures ambient temperature.

Capacitive sensing is typically used to detect finer grain touch, proximity, and actions such as fingers sliding on a surface. Inductive sensing can distinguish coarse grain touch, up to 256 levels of force, and actions such as knob rotation, while the Hall effect sensor detects magnetic fields, such as those from a magnet embedded in a docking station.

The integration of multiple sensors on a single chip achieves a number of critical goals, including reduced power, size, weight, and cost; easier sensor calibration and configuration; lower latency (critical for gaming and touch error mitigation); greater ability to execute more tightly coupled and accurate compensation algorithms to ensure baseline stability and adjust for temperature drift to enhance overall reliability and performance; and lower assembly cost, higher yield, and a simplified supply chain due to the use of a single device instead of multiple discrete components.

The result is a single highly flexible, stable, and reliable sensor processor measuring 2.62mm2, that can replace up to four ICs with a combined size of 16.04mm2 for an 80% decrease in footprint. It consumes 240µW (typically) in-ear (for a TWS application), and 10µW in a dock or “sleep” mode.

For developers, the FlexSense family accelerates time to market by providing a simple, highly configurable, out-of-the box solution with a single processor and up to eight analog input channels that can be configured to mix and match up to four different sensors. Developers can use Synaptics’ powerful FlexSense Configuration Tool to tune all inputs through a single interface, allowing rapid development and deployment of end solutions.

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