Capacitance-to-Digital Converters

Moisture sensing with capacitance-to-digital converter

ScioSense offers a family of signal conditioners for capacitive sensors that are outstanding in regards of flexibility and performance.

These capacitance-to-digital converters are based on the patented PICOCAP measuring principle, which uses precision discharge time measurement to get the ratio of sensor capacitance versus reference capacitance. 

By means of our TDC technology we can measure with picosecond resolution which allows us to have very short discharge time in the few microseconds range. The input capacitance can range between a Picofarad and hundreds of Nanofarads, which means that there is almost no limit to the size of capacitor. 

The multi-channel CDC provides a high degree of flexibility with respect to accuracy, speed and operating current. By means of a variation in averaging and sample rate users can switch from high resolution (20 Bit) to low power (3 µA) to high speed (50 kHz). A powerful integrated CPU enables on-chip linearization and temperature measurement and compensation.

Capacitance-to-Digital Converters

Channels

6

8

8

Resolution

20 Bit
8 aF

19 Bit
15 aF

20 Bit
6 aF

Max sample
rate [Hz]

500k

500k

50k

Capacitance range [F]

1p to 100n

1p to 100n

1p to 100n

I [μA]

3 @ 3 Hz/13 Bit

3 @ 3 Hz/13 Bit

3 @ 3 Hz/13 Bit

Memory

1k NVRAM
3k ROM

4k SRAM
4k OTP

4k SRAM
4k OTP

CPU

32 Bit

48 Bit

48 Bit

Interface

SPI/I2C/
PDM/PWM

SPI/I2C/
PDM/PWM

SPI/I2C

Package

QFN24

QFN32

QFN32