AD7879

Rev. 0 | Page 2 of 36

TABLE OF CONTENTS

Features .............................................................................................. 1

Applications....................................................................................... 1

Functional Block Diagram .............................................................. 1

General Description ......................................................................... 1

Revision History ............................................................................... 2

Specifications..................................................................................... 3

SPI Timing Specifications (AD7879)......................................... 4

I2C Timing Specifications (AD7879-1) ..................................... 5

Absolute Maximum Ratings............................................................ 6

ESD Caution.................................................................................. 6

Pin Configuration and Function Descriptions............................. 7

Typical Performance Characteristics ............................................. 8

Terminology .................................................................................... 11

Theory of Operation ...................................................................... 12

Touch Screen Principles ............................................................ 12

Measuring Touch Screen Inputs............................................... 13

Touch-Pressure Measurement .................................................. 14

Temperature Measurement ....................................................... 14

Median and Averaging Filters ....................................................... 16

AUX/VBAT/GPIO Pin................................................................... 17

Auxiliary Input ........................................................................... 17

Battery Input ............................................................................... 17

Limit Comparison...................................................................... 17

GPIO ............................................................................................ 17

Register Map ................................................................................... 19

Detailed Register Descriptions ..................................................... 20

Control Registers ............................................................................ 24

Control Register 1 ...................................................................... 24

Control Register 2 ...................................................................... 26

Control Register 3 ...................................................................... 27

Interrupts..................................................................................... 28

Synchronizing the AD7879 to the Host CPU......................... 29

Serial Interface ................................................................................ 30

SPI Interface ................................................................................ 30

I2C-Compatible Interface .......................................................... 32

Grounding and Layout .................................................................. 35

Chip Scale Packages ................................................................... 35

WLCSP Assembly Considerations........................................... 35

Outline Dimensions ....................................................................... 36

Ordering Guide .......................................................................... 36

REVISION HISTORY

10/08—Revision 0: Initial Version