AD7745

24-bit, 1 Channel Capacitance to Digital Converter
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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 features 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 Lifecycle

checked 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

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Product Details

The EVAL-AD7746EBZ is a fully featured evaluation board for the AD7746. The evaluation board is operated with a PC via a standard USB connection with software provided enabling the user to perform detailed analysis of the CDC's performance. This software includes the technical note describing the operation and set up of the evaluation board.

Design Resources

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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.

AD7745 Material Declaration
PCN-PDN Information Quality And Reliability Symbols and Footprints

Reviews

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Overview

3 Reviews
3 out of 3 (100%) customers recommend this product.
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Most Helpful Review

by Anonymous
We used your application note for the practical application of the device to calculate the active sensor circuit RH. We were pleased

Most Recent Review

by Tomas D.
We applied this product for capacitive sensing in liquids. We were amaized by it's performance. Two wire interface provided convenient data transmission. Moreover, micro power consumption allowed operation from the battery.

All Reviews

by Tomas D., 13 Jun 14
This product offers high performance and is user-friendly
We applied this product for capacitive sensing in liquids. We were amaized by it's performance. Two wire interface provided convenient data transmission. Moreover, micro power consumption allowed operation from the battery.
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by Anonymous, 15 Apr 14
Excellent capacitance-to-digital converter
The AD7745 is a high resolution capacitance-to-digital converter, which offer direct interface with a capacitance passive component.
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by Anonymous, 11 Dec 12
I liked this product
We used your application note for the practical application of the device to calculate the active sensor circuit RH. We were pleased
Was this Helpful?Helpful(0)

Sample & Buy

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The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.


Price Table Help

 
Evaluation Boards Pricing displayed is based on 1-piece.
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.