Description

The ZSSC3122 cLite is a CMOS integrated circuit for accurate capacitance-to-digital conversion and sensor-specific correction of capacitive sensor signals. Digital compensation of sensor offset, sensitivity and temperature drift is accomplished via an internal digital signal proessor running a correction algorithm with calibration coefficients stored in a non-volatile EEPROM.

The ZSSC3122 is configurable for capacitive sensors up to 10 pF and a sensitivity of 125aF/LSB. It is compatible with both single capacitive sensors (both terminals must be accessible) and differential capacitive sensors. Measured and corrected sensor values can be output as I2C, SPI, PDM or alarms.

The I2C interface can be used for a simple PC-controlled calibration procedure to program a set of calibration coefficients into an on-chip EEPROM. The ZSSC3122 and a specific sensor are mated digitally; fast, precise and without the cost overhead of trimming by external devices or laser.

Features

• Maximum target input capacitance: 10pF
• Sampling rates as fast as 0.7 ms @8-bit; 1.6 ms@10-bit; 5.0 ms@12-bit, 18.5 ms@14-bit
• Digital compensation of sensor; piece-wise 1st and 2nd order sensor compensation or up to 3rd order sensor-region sensor compensation
• Digital compensation of 1st and 2nd order temperature gain and offset drift
• Internal temperature compensation reference
• Programmable capacitance span and offset
• Layout customized for die-die bonding with sensor for low-cost, high-density chip-on-board assembly
• Accuracy as high as +/-0.25 FSO@ -40 to 125C, 3V, 5V, vsupply +/-10%

Benefits

• Minimize calibration costs: no laser trimming, one-pass calibration using a digital interface
• Excellent for low-power battery applications
• I2C or SPI interface
• PDM outputs for both capacitance and temperature
• Up to two alarms that can act as a full push-pull or open-drain switches