24-bit, 1 Channel Capacitance To Digital Converter

The AD7745 AD7746 are a high resolution, - capacitance-to-digital converter (CDC). The capacitance to be measured is connected directly to the device inputs. The architecture features inherent high resolution (24-bit no missing codes, up to 21-bit effective resolution), high linearity (0.01%), and high accuracy (4 fF factory calibrated). The AD7745 AD7746 capacitance input range is 4 pF (changing), while it CAN accept up to 17 pF common-mode capacitance (not changing), which CAN be balanced by a programmable on-chip, digital-to-capacitance converter (CAPDAC).
The AD7745 has one capacitance input channel, while the AD7746 has two channels. Each channel CAN be configured as single-ended or differential. The AD7745 AD7746 are designed for floating capacitive Sensors For capacitive Sensors with one plate connected to ground, the AD7747 is recommended.
The parts have an on-chip Temperature Sensor with a resolution of 0.1C and accuracy of 2C. The on-chip Voltage Reference and the on-chip Clock Generator eliminate the need for any external components in capacitive Sensor applications. The parts have a standard voltage input, which together with the differential reference input allows easy Interface to an external Temperature Sensor such as an RTD, thermistor, or Diode
The AD7745 AD7746 have a 2-wire, I2C-compatible serial Interface Both parts CAN operate with a single power supply from 2.7 V to 5.25 V. They are specified over the automotive temperature range of 40C to +125C and are housed in a 16-lead TSSOP package.
Applications Automotive, Industrial and Medical Systems for: Pressure Measurement Position Sensors Level Sensors Flowmeters Humidity Sensors Impurity Detection
By Analog Devices, Inc.