资 源 简 介
The AD7747 is a high-resoluTIon， Σ-Δ 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 19.5-bit effecTIve resoluTIon）， high linearity （±0.01%）， and high accuracy （±10 fF factory calibrated）。 The AD7747 capacitance input range is ±8 pF （changing）， and 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 AD7747 is designed for single-ended or differential capacitive sensors with one plate connected to ground. For floating （not grounded） capacitive sensors， the AD7745 or AD7746 are recommended. The part has an on-chip temperature sensor with a resolution of 0.1°C and accuracy of ±2°C. The on-chip voltage reference and the on-chip clock generator eliminate the need for any external components in capacitive sensor applications. The part has a standard voltage input that， together with the differential reference input， allows easy interface to an external temperature sensor， such as an RTD， thermistor， or diode. The AD7747 has a 2-wire， I2 C-compatible serial interface. The part can operate with a single power supply of 2.7 V to 5.25 V. It is specified over the automotive temperature range of −40°C to +125°C and is housed in a 16-lead TSSOP package.
