explain

The AD7745/AD7746 is a high resolution, Σ-Δ Capacitive to Digital Converter (CDC). The capacitance to be measured is directly connected to the device input. The architecture has inherent high resolution (24 bit no missing code, up to 21 bit effective resolution), high linearity (± 0.01%), and high precision (± 4 fF factory calibration). The capacitance input range of the AD7745/AD7746 is ± 4pF (change), while it can accept up to 17 pF of common mode capacitance (unchanged), which can be balanced by a programmable on-chip digital capacitance converter (CAPDAC).

The AD7745 has one capacitive input channel and the AD7746 has two channels. Each channel can be configured as a single terminal or a differential. The AD7745/AD7746 is designed for floating capacitive sensors. For capacitive sensors that connect a board to ground, the AD7747 is recommended.

The component has an on-chip temperature sensor with a resolution of 0.1 ° C and an accuracy of ± 2 ° C. The on-chip voltage reference and on-chip clock generator eliminate the need for any external components in capacitive sensor applications. These components have a standard voltage input that, together with the differential reference input, allows easy connection to external temperature sensors such as RTDs, thermistors, or diodes.

The AD7745/AD7746 has a 2-wire, i2c compatible serial interface. Both components can operate on a single power supply from 2.7 V to 5.25 V. They can be specified within the vehicle temperature range of - 40 ° C to+125 ° C and installed in a 16 lead TSSOP package.

Impurity detection