Sensor Signal Conditioner


Low Voltage Capacitive Sensor Signal Conditioner with Digital Output
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Brief 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 processor running a correction algorithm with calibration coefficients stored in a non-volatile EEPROM.
The ZSSC3122 is configurable for capacitive sensors with capacitances up to 10pF 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™ (trademark of NXP), 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 calibrated ZSSC3122 and a specific sensor are mated digitally: fast, precise, and without the cost overhead of trimming by external devices or laser.

Key Features
  • Maximum target input capacitance: 10pF
  • Sampling rates as fast as 0.7ms @ 8-bit; 1.6ms @ 10-bit; 5.0ms @ 12-bit; 18.5ms @ 14-bit
  • Digital compensation of sensor: piece-wise 1st and 2nd order sensor compensation or up to 3rd order single-region sensor compensation
  • Digital compensation of 1st and 2nd order temperature gain and offset drift
  • Internal temperature compensation reference (no external components)
  • 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@ -20 to 125°C, 3V, 5V, Vsupply ±10% (see data sheet for restrictions)


Physical Characteristics
  • Supply voltage: 1.8 to 5.5V
  • Typical current consumption 650μA down to 60μA depending on configuration
  • Typical Sleep Mode current: ≤ 1μA at 85°C
  • Operation temperature: –20°C to +125°C
  • Die or TSSOP14 package
  • Minimized calibration costs: no laser trimming, one-pass calibration using a digital interface
  • Excellent for low-power battery applications