Overview
Features and Benefits
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Product Details
The AD7745/AD7746 are a high resolution, Σ-Δ 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.
Applications
Automotive, Industrial and Medical Systems for:
- Pressure Measurement
- Position Sensors
- Level Sensors
- Flowmeters
- Humidity Sensors
- Impurity Detection
Product Categories
Markets and Technologies
Product Lifecycle
Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
Documentation & Resources
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FAQs7/26/2017
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Liquid Level Sensing Using Capacitive-to-Digital Converters4/1/2015 Analog Dialogue
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Capacitance-to-Digital Converter Facilitates Level Sensing in Diagnostic Systems4/1/2014 Analog Dialogue
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ADI Capacitance-to-Digital Converter Technology in Healthcare Applications5/1/2012 Analog Dialogue
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Designing Power Supplies for High Speed ADC2/1/2012
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Boost Precision and Accuracy with Single Chip Capacitance- and Impedance-to-Digital Converters8/1/2007 Analog Dialogue
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Delta-Sigma Rocks RF, As ADC Designers Jump On Jitter1/12/2006
Software & Systems Requirements
Evaluation Software
Reference Designs (1)
Design Resources
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.View our quality and reliability program and certifications for more information.
| Part Number | Material Declaration | Reliability Data | Pin/Package Drawing | CAD Symbols, Footprints & 3D Models |
|---|---|---|---|---|
| AD7746ARUZ | Material Declaration | Reliability Data | 16-Lead TSSOP | |
| AD7746ARUZ-REEL | Material Declaration | Reliability Data | 16-Lead TSSOP | |
| AD7746ARUZ-REEL7 | Material Declaration | Reliability Data | 16-Lead TSSOP | |
| Wafer Fabrication Data |
PCN-PDN Information
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Support & Discussions
AD7746 Discussions
RE: Labview source code for AD7746 Capacitive Level Sensor Demo v2.2
16 week(s) ago in Precision ADCs
Sample & Buy
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Lead Times
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Sampling
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Evaluation Boards
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.