Large screen capacitive touch panel controller

STAR2000 is a touch panel controller ASIC for projective-capacitive touch screens (PCTS) as large as 17”, and is highly configurable to work optimally for different touch panel sizes. Multiple STAR2000 ICs can also be connected together for larger screen sizes, up to 34”. With full Windows 8 compliance the ASIC can detect >12 simultaneous touches while consuming <72mW of power. Its scalable architecture enables support of more simultaneous touch points up to and beyond 25. Multi-touch sensing circuitry for PCTS has traditionally driven rows one at a time with short pulse bursts, then multiplexed receive signals into a high-resolution ADC to sense coupling capacitances between rows and columns. Small changes, on the order of 100fF, are used to detect touch. Accurate sensing is difficult because panels are exposed to interference from both the display and from the user, and it is common to boost drive voltages on the rows up to 10V and beyond in order to improve SNR, requiring an high voltage process technology.

STAR2000 uses a proprietary drive/sense technique to mitigate the requirement of a high-voltage (HV) process. Thus STAR2000 can be fabricated using a standard CMOS process enabling the use of other IPs (e.g. Flash and OTP, etc.) which are typically not available in HV processes. Based on CDMA techniques, STAR2000 modulates and drives TX signal patterns into multiple TX-lines differentially captures, digitize and demodulates the received signals. A small embedded 8-bit microprocessor is integrated to the controller IC along with a simple touch detection DSP engine to perform rudimentary touch detection functions before sending data for further processing by an external MCU running computationally intensive touch and gesture algorithms in firmware.