Harsh-duty touch sensor conditioner for battery apps
ProductMay 24, 2011
Alice Moss
Military Embedded Systems
Chris A. Ciufo
General Micro Systems, Inc.
The human-machine interface in defense apps is critically important - especially when it comes to pushing buttons or scrolling pages.
The human-machine interface in defense apps is critically important – especially when it comes to pushing buttons or scrolling pages. Designed for use in non-contact applications where harsh or explosive environments don’t favor electric-spark buttons, virtual buttons on LCD and other screens are becoming the de facto way to control embedded computers. In low-power and battery-operated systems, it’s the capacitive overlay that humans use to manipulate on-screen objects like buttons. But those touch screens require capacitive signal conditioners like the wide-dynamic range ZSSC3122 by ZMDI.
Primary specs boast 14-bit capacitive to digital conversion, with sensitivity, sensor offset, and temperature digitally corrected via algorithm. Designed to sip 60 microA over a voltage range of 1.8 V to 5.5 V, the conditioner interfaces to capacitive sensors from 2 to 10 pF with a sensitivity down to an astounding 120 atto-Farads (aF) per digital bit and accuracy up to 0.25 percent over -40 °C to +125 °C. Calibration for the device is digital and corrects first- and third-order nonlinearity errors, making it ideal for the high-humidity and -pressure applications found in military systems. Calibration coefficients are stored onboard in EEPROM. Designed to be interfaced to a microcontroller, the ZSSC3122 can also be used stand-alone in transducer and switch applications. Programming is accomplished via a PC with ZMDI development tools. If you’ve got a capacitive touch system, you need these controllers. Trust us.
