HV capacitive touchscreen line driver boosts touch performance

October 14, 2014 // By Graham Prophet
Microchip Technology has added a standalone integrated high-voltage line driver to increase Signal-to-Noise Ratio (SNR) for advanced projected-capacitive touch performance.

MTCH652 features an integrated boost converter and can interface to any touch controller via SPI to drive up to 19 transmit (Tx) channels at selectable voltages up to 18V to increase the SNR in projected capacitive touch systems. The improved SNR increases the robustness of the system in noisy environments, allows thicker cover lenses, and reduces the number of samples and time required by the touch controller to scan large displays. These capabilities are especially important in demanding environments such as white goods, automotive (e.g., dashboard infotainment and navigation controls), PC peripherals and industrial controls (e.g., machine interface) markets.

Microchip's 3DTouchPad DM160225 incorporates the MTCH652 and demonstrates its advantages including advanced touch performance in a noise robust design. The MTCH652’s higher SNR enables Electromagnetic Compatibility (EMC) resistance and is a versatile companion chip to advance multi-touch performance.

“Microchip’s new high-voltage driver MTCH652 provides the industry with a simple high-voltage boost solution that can improve robustness and increase the sensor sizes for today’s touch controllers,” said Fanie Duvenhage, director of Microchip’s Human-Machine Interface Division. “The wide range of input and output voltages supported combined with the ability to daisy chain the MTCH65X devices give our customers more flexibility in their designs.”

A user endorsement comes from Lillian Chao, president of Apex Material Technology Corp (AMT);

“The addition of Microchip’s MTCH652 to our projected-capacitive electronics solution resulted in a more robust design that supports larger size displays up to 24 in. and facilitated passing 10 V/m for Radiated Susceptibility (RS) testing and 10 Vrms for Conducted Susceptibility (CS) testing (according to IEC61000-4-3 Level 3 and IEC61000-4-6 Level 3)... using the MTCH652 helped AMT achieve advanced features such as water immunity and gloved input. Also, AMT was able to easily integrate multiple MTCH652 chips to support larger designs.”

The MTCH652 is supported by Microchip’s 3DTouchPad (part # DM160225, $99.00). The MTCH652 in 28-pin QFN, SOIC and SSOP packages is priced from $1.04 (10,000).