AD7747

24位电容至数字转换器，温度传感器 24-Bit Capacitance-to-Digital Converter with Temperature Sensor

Product Details

The 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:

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Pressure measurement

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Position sensing

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Proximity sensing

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Level sensing

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Flowmeters

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Impurity detections

### Features and Benefits

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New standard in single chip solutions

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Interfaces to single or differential grounded sensors

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Resolution down to 20 aF that is, up to 19.5-bit ENOB

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Accuracy: 10 fF

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Linearity: 0.01%

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Common-mode not changing capacitance up to 17 pF

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Full-scale changing capacitance range ±8 pF

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Update rate: 5 Hz to 45 Hz

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Simultaneous 50 Hz and 60 Hz rejection at 8.1 Hz update

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Active shield for shielding sensor connection

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Temperature sensor on-chip

Resolution: 0.1°C, accuracy: ±2°C

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Voltage input channel

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Internal clock oscillator

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2-wire serial interface I2C® compatible

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Power

2.7 V to 5.25 V single-supply operation

0.7 mA current consumption

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Operating temperature: -40°C to +125°C

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16-lead TSSOP package

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