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AD7156:  Ultralow Power, 1.8 V, 3 mm × 3 mm, 2-Channel Capacitance Converter

Product Details

The AD7156 delivers a complete signal processing solution for capacitive sensors, featuring an ultralow power converter with fast response time.

The AD7156 uses an Analog Devices, Inc., capacitance-to-digital converter (CDC) technology, which combines features important for interfacing to real sensors, such as high input sensitivity and high tolerance of both input parasitic ground capacitance and leakage current.

The integrated adaptive threshold algorithm compensates for any variations in the sensor capacitance due to environmental factors like humidity and temperature or due to changes in the dielectric material over time.

By default, the AD7156 operates in standalone mode using the fixed power-up settings and indicates detection on two digital outputs. Alternatively, the AD7156 can be interfaced to a micro-controller via the serial interface, the internal registers can be programmed with user-defined settings, and the data and status can be read from the part.

The AD7156 operates with a 1.8 V to 3.6 V power supply. It is specified over the temperature range of −40°C to +85°C.


  • Buttons and switches
  • Proximity sensing
  • Contactless switching
  • Position detection
  • Level detection
  • Portable products


  • Ultralow power
    Power supply voltage: 1.8 V to 3.6 V
    Operation power supply current: 70 μA typical
    Power-down current: 2 μA typical
  • Fast response time
    Conversion time: 10 ms per channel
    Wake-up time from serial interface: 300 μs
  • Adaptive environmental compensation
  • 2 capacitance input channels
    Sensor capacitance (CSENS): 0 pF up to 13 pF
    Sensitivity up to 3 fF
  • 2 modes of operation
    Standalone with fixed settings
    Interfaced to a microcontroller for user-defined settings
  • 2 detection output flags
  • 2-wire serial interface (I2C-compatible)
  • Operating temperature: −40°C to +85°C
  • 10-lead LFCSP package (3 mm × 3 mm × 0.8 mm)

Functional Block Diagram for AD7156


Title Content Type File Type
AD7156: Ultralow Power, 1.8 V, 3 mm × 3 mm, 2-Channel Capacitance Converter Data Sheet (Rev 0, 10/2008) (pdf, 527 kB) Data Sheets PDF
AN-1048: AD7150 On-Chip Noise Filter  (pdf, 92 kB) Application Notes PDF
Webcast: Design And Develop Innovative And Robust Touch Sensor Interfaces Using Capacitive-To-Digital Converters
This Webcast will focus on the design and development of CDC-based touch sensors and their application, cite CDC product examples such as the AD7142, and explore development tools provided by ADI.
Webcasts WEBCAST
MS-2210: Designing Power Supplies for High Speed ADC  (pdf, 327 kB) Technical Articles PDF
2008 Medical Solution Profile  (pdf, 126 kB)
High Performance ICs for Medical Imaging, Patient Monitoring, and Instrumentation
Overview PDF
What are Capacitive Sensors and how are they used? FAQs/RAQs HTML
RAQs index Rarely Asked Questions HTML
Glossary of EE Terms Glossary HTML

Evaluation Kits & Symbols & Footprints

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Symbols and Footprints— Analog Devices offers Symbols & Footprints which are compatible with a large set of today’s CAD systems for broader and easier support.

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Price, packaging, availability

AD7156 Model Options
Price Table Help

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.

AD7156 Evaluation Board
Model Description Price RoHS View PCN/ PDN Check Inventory/
EVAL-AD7156EBZ Status: Production Evaluation Board $59.00 Yes -

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.

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