Product Details
●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, I2C-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.
●Applications
●Automotive, industrial, and medical systems for:
● Pressure measurement
● Position sensing
● Proximity sensing
● Level sensing
● Flowmeters
● Impurity detections
●### Features and Benefits
● New standard in single chip solutions
● Interfaces to single or differential grounded sensors
● Resolution down to 20 aF (that is, up to 19.5-bit ENOB)
● Accuracy: 10 fF
● Linearity: 0.01%
● Common-mode (not changing) capacitance up to 17 pF
● Full-scale (changing) capacitance range ±8 pF
● Update rate: 5 Hz to 45 Hz
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● Simultaneous 50 Hz and 60 Hz rejection at 8.1 Hz update
● Active shield for shielding sensor connection
● Temperature sensor on-chip
●Resolution: 0.1°C, accuracy: ±2°C
● Voltage input channel
● Internal clock oscillator
● 2-wire serial interface (I2C® compatible)
● Power
●2.7 V to 5.25 V single-supply operation
●0.7 mA current consumption
● Operating temperature: -40°C to +125°C
● 16-lead TSSOP package
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