12-Bit Capacitance-to-Digital Converter (1 Capacitance Input Channel)

The AD7152/AD7153 are 12-bit sigma-delta (Σ-Δ) capacitance-to-digital converters (CDCs). The capacitance to be measured is connected directly to the device inputs. The architecture features inherent high resolution (12-bit no missing codes, up to 12-bit effective resolution) and high linearity (±0.05%). The AD7152/ AD7153 have four capacitance input ranges per operation mode, ±0.25 pF to ±2 pF in differential mode and 0.5 pF to 4 pF in single-ended mode.

The AD7152/AD7153 can accept up to 5 pF common-mode capacitance (not changing), which can be balanced by a programmable on-chip, digital-to-capacitance converter (CAPDAC).

The AD7153 has one capacitance input channel, while the AD7152 has two channels. Each channel can be configured as single-ended or differential. The AD7152/AD7153 are designed for floating capacitive sensors.

The AD7152/AD7153 have a 2-wire, I2C-compatible serial interface. Both devices can operate with a single power supply from 2.7 V to 3.6 V. They are specified over the temperature range of −40°C to +85°C and are available in a 10-lead MSOP.

Applications

Automotive, industrial, and medical systems for

* Pressure measurement

* Position sensing

* Level sensing

* Flowmeters

* Humidity sensing

* Capacitance-to-digital converters

* Interfaces to floating sensors

* Resolution down to 0.25 fF (that is, up to 12 ENOB)

* Linearity: 0.05%

* Common-mode (not changing) capacitance up to 5 pF

* Four capacitance ranges selectable per operation mode

* Tolerant of parasitic capacitance to ground up to 50 pF

* Conversion time per channel: 5 ms, 20 ms, 50 ms, and 60 ms