AMS has announced a configurable capacitive sensing front end which allows speed and resolution to be traded to optimise designs.

Called PCap04, it can capture and digitise 50,000 times per second at its fastest setting, or achieve 8aF resolution at its most sensitive.

“Configurability also enables sensor manufacturers to trade measurement speed off against power consumption. In low-power mode, it draws as little as 4µA,” said the firm. “AMS has developed a demonstration board with no external power supply, in which the PCap04 operates on the energy harvested from the RF field generated by an NFC reader.”

The chip is intended for use with any sensing element that generates a change in capacitance. With its six capacitance measurement channels, it can measure six grounded capacitors or three floating capacitors. Differential and differential grounded sensor connections are also supported.

Sensible capacitors include anything between 1pF and 100nF.

The output can be a PWM or PDM representation of the raw measured capacitance, and an internal DSP is available to process the sensor measurements and send results out over I2C or SPI. The DSP can run AMS open-source code as well as user-generated code for functions such as measurement linearisation, temperature compensation or conversion.

There is a demo board and a software development tool for development, test and debug.

It comes as a bare die or in a QFN-24.

“PCap04 gives sensor manufacturers a flexible alternative to other sensor front ends on the market today that have have fixed operating characteristics,” claimed AMS marketing director Jose Vinau. “It offers the advantage of enabling sensor manufacturers to fine-tune the operation of the sensor front end to meet the requirements of their specific application.”

Applications are expected measuring parameters such as pressure, force, position, tilt, humidity, weight and level, amongst others.