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AD7877:  Touch Screen Controller

Product Status:Production
Data
Sheet
AD7877 Data Sheet Rev D, 12/2011 (pdf 795kB)

Product Details

Product Status:Production
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Automotive Qualified

The AD7877 is a 12-bit, successive approximation ADC with a synchronous serial interface and low on resistance switches for driving touch screens. The AD7877 operates from a single 2.7 V to 5.25 V power supply (functional operation to 2.2 V), and features throughput rates of 125 kSPS. The AD7877 features direct battery measurement on two inputs, temperature and touch-pressure measurement.

The AD7877 also has an on-board reference of 2.5 V. When not in use, it can be shut down to conserve power. An external reference can also be applied and varied from 1 V to +VCC, with an analog input range of 0 V to VREF. The device includes a shutdown mode that reduces its current consumption to less than 1 μA.

To reduce the effects of noise from LCDs, the acquisition phase of the on-board ADC is controlled via the STOPACQ pin. User-programmable conversion controls include variable acquisition time and first conversion delay. Up to 16 averages can be taken per conversion. There is also an on-board DAC for LCD back-light or contrast control. The AD7877 runs in either slave or master mode using a conversion sequencer and timer. It is ideal for battery-powered systems such as personal digital assistants with resistive touch screens and other portable equipment.

The part is available in a 32-lead lead frame chip scale package (LFCSP), and a 25-ball wafer level chip scale package (WLCSP). AD7877W model is qualified for automotive applications.

Applications

  • Personal digital assistants
  • Smart hand-held devices
  • Touch screen monitors
  • Point-of-sale terminals
  • Medical devices
  • Cell phones
  • Pagers

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FEATURES and BENEFITS

  • 4-wire touch screen interface
  • LCD noise reduction feature (STOPACQ pin)
  • Automatic conversion sequencer and timer
  • User-programmable conversion parameters
  • On-chip temperature sensor:
    −40°C to +85°C
  • On-chip 2.5 V reference
  • On-chip 8-bit DAC
  • 3 auxiliary analog inputs
  • 1 dedicated and 3 optional GPIOs
  • 3 interrupt outputs
  • 2 direct battery measurement channels (0.5 V to 5 V)
  • Qualified for automotive applications
  • See Data Sheet for additional features

Functional Block Diagram for AD7877

AD7877 Diagram
Typical Applications and Other Diagrams

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Documentation

Title Content Type File Type
AD7877: Touch Screen Controller Data Sheet (Rev D, 12/2011) (pdf, 795 kB) Data Sheets PDF
AN-753: Configuring the AD7877  (pdf, 247 kB) Application Notes PDF
AN-766: Using the Noise Reduction Feature on the AD7877  (pdf, 409 kB) Application Notes PDF
AN-738: Using the AD7877 Touch Screen Controller and the Intel PXA250 Processor Under Windows CE.NET  (pdf, 60 kB) Application Notes PDF
MS-2210: Designing Power Supplies for High Speed ADC  (pdf, 327 kB) Technical Articles PDF
As Systems Shrink in Size, Input Becomes More Difficult
... For direct input on a display, like in the case of a Palm-like PDA, Analog Devices offers its AD7877 touch-screen digitizer. (Portable Design, 6/2003) 		Product Reviews HTML
Healthcare ICs
Healthcare ICs Solutions Bulletin, Volume 11, Issue 2 		Solutions Bulletins HTML
ICs for Enhanced Handset User Experience Overview HTML
Products for Wireless Handset Applications  (pdf, 1441 kB) Overview PDF
Product Solutions for Handset Applications  (pdf, 349 kB) Overview PDF
LEADING Semiconductors for Wireless Handsets Brochure  (pdf, 1923 kB) Overview PDF
RAQs index Rarely Asked Questions HTML
Glossary of EE Terms Glossary HTML

Design Tools,Models,Drivers & Software

Title Content Type File Type
AD7877 Input Touch Screen Controller Linux Driver (Wiki Site) Device Drivers HTML

Evaluation Kits & Symbols & Footprints

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

AD7877 Model Options
Model Package Pins Temp.
Range 		Packing,
Qty 		Price*(100-499) Price*1000 pcs RoHS View PCN/ PDN Check Inventory/
Purchase/Sample
AD7877ACBZ-REEL Status: Production 25 Ball WLCSP 25 Ind Reel, 10000 $2.20 $2.15 Y  Material Info PCN Purchase
AD7877ACBZ-REEL7 Status: Production 25 Ball WLCSP 25 Ind Reel, 3000 - $2.15 Y  Material Info PCN Purchase Sample
AD7877ACPZ-500RL7 Status: Production 32 ld LFCSP (5x5mm CP-32-2) 32 Ind Reel, 500 - $2.15 Y  Material Info PCN Purchase Sample
AD7877ACPZ-REEL Status: Production 32 ld LFCSP (5x5mm CP-32-2) 32 Ind Reel, 5000 - $2.15 Y  Material Info PCN Purchase
AD7877ACPZ-REEL7 Status: Production 32 ld LFCSP (5x5mm CP-32-2) 32 Ind Reel, 1500 - $2.15 Y  Material Info PCN Purchase Sample
AD7877WACPZ-REEL7 Status: Production 32 ld LFCSP (5x5mm CP-32-2) 32 Ind Reel, 1500 - $2.30 Y  Material Info Notify Me Purchase Sample
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.

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