Controller ICs ease touch-sensor design

To support the adoption of capacitive touch sensors in portable devices, Rohm has introduced a series of controller ICs that ease design-in, eliminate external components and enable significant power savings compared to existing technologies.

The BU21010MUV and BU21008MUV controllers provide eight and sixteen sensor channels respectively. Up to half of the available channels may be configured as LED drivers to implement tactile feedback.

Sensing capabilities include gesture identification, as well as long-push, short-push and slide detection. PWM control for LEDs is also included. A third controller, the BU21009MUV for two-dimensional arrays, supports matrix resolution up to 48 x 80, and provides eight LED-driver channels.

All the devices eliminate external components by providing on-chip clocking and Power-On Reset (POR) circuitry, and by implementing internal configuration registers to replace external tuning components. The registers are controlled from the host processor via a standard I²C interface, which is also provided.

The amplifiers’ voltage feedback design topology provides balanced inputs and high open-loop gain for ease of use and accuracy in applications such as active filter design. Offset voltage is typically 0.1mV and settling time to 0.01% is 120ns which, combined with a 100dBc SFDR at 100kHz, makes the parts suitable for use as an input buffer for popular 8-bit, 10-bit, 12-bit and 14-bit megasample ADCs.

By performing both the sensor-processing duties and application functions on chip, the controllers also reduce the load on the host CPU.

 

FEATURES Analogue supply-voltage range: 2.5V to 3.3V Digital supply-voltage range: 1.7V to 3.3V 250µA current draw in active-mode 50µA idle mode Zero-current standby mode

APPLICATIONS Security control panels Domestic appliances Industrial user interfaces Medical equipment

 

 

Rohm/BU210xxMUV