Description

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 fea-tures 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 0.1?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 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 ?40?C to +125?C and are housed in a 16-lead TSSOP package. ApplicationsAutomotive, Industrial and Medical Systems for: Pressure Measurement Position Sensors Level Sensors Flowmeters Humidity Sensors Impurity Detection

Type:

Part number: EVAL-AD7746LDZ

More details from Analog Devices Inc.