Datasheet

AD7879/AD7889
Rev. C | Page 2 of 40
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Functional Block Diagram .............................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
SPI Timing Specifications (AD7879/AD7889)......................... 4
I
2
C Timing Specifications (AD7879-1/AD7889-1).................. 5
Absolute Maximum Ratings ............................................................ 6
Thermal Resistance ...................................................................... 6
ESD Caution .................................................................................. 6
Pin Configurations and Function Descriptions ........................... 7
Typical Performance Characteristics ............................................. 9
Terminology .................................................................................... 12
Theory of Operation ...................................................................... 13
Touch Screen Principles ............................................................ 13
Measuring Touch Screen Inputs ............................................... 14
Touch-Pressure Measurement .................................................. 15
Temperature Measurement ....................................................... 15
Median and Averaging Filters ....................................................... 17
AUX/VBAT/GPIO Pin ................................................................... 18
Auxiliary Input ........................................................................... 18
Battery Input ............................................................................... 18
Limit Comparison ...................................................................... 18
GPIO ............................................................................................ 18
Conversion Timing ........................................................................ 20
Register Map ................................................................................... 21
Detailed Register Descriptions ..................................................... 22
Control Registers ............................................................................ 26
Control Register 1 ...................................................................... 26
Control Register 2 ...................................................................... 28
Control Register 3 ...................................................................... 29
Interrupts ..................................................................................... 30
Synchronizing the AD7879/AD7889 to the Host CPU ........ 31
Serial Interface ................................................................................ 32
SPI Interface ................................................................................ 32
I
2
C-Compatible Interface .......................................................... 34
Grounding and Layout .................................................................. 37
Lead Frame Chip Scale Packages ............................................. 37
WLCSP Assembly Considerations ........................................... 37
Outline Dimensions ....................................................................... 38
Ordering Guide .......................................................................... 39
REVISION HISTORY
11/10—Rev. B to Rev. C
Changes to Table 2 ............................................................................ 3
Added Conversion Timing Section .............................................. 20
Added Figure 34 .............................................................................. 29
1/10—Rev. A to Rev. B
Updated Outline Dimensions ....................................................... 37
Changes to Ordering Guide .......................................................... 38
3/09—Rev. 0 to Rev. A
Added AD7889 and Backside-Coated WLCSP ......... Throughout
Change to Battery Monitor, Input Voltage Range Parameter ..... 3
Changes to Table 4 ............................................................................ 6
Added Thermal Resistance Section and Table 5;
Renumbered Sequentially ................................................................ 6
Changes to Pin Configurations and Function Descriptions
Section ................................................................................................ 7
Added Table 7 .................................................................................... 8
Changes to First Method Section ................................................. 15
Changes to Median and Averaging Filters Section .................... 17
Changes to GPIO Interrupt Enable (Bit 12, Control Register 3,
Address 0x03) Section ................................................................... 19
Changes to Table 13 ....................................................................... 22
Changes to ADC Channel (Control Register 1, Bits[14:12])
Section .............................................................................................. 26
Changes to Power Management (Control Register 2,
Bits[15:14]) Section ........................................................................ 27
Changes to
DAV
—Data Available Interrupt Section ................. 29
Changes to
INT
—Out-of-Limit Interrupt Section .................... 29
Changes to Writing Data Section ................................................. 31
Changes to Reading Data Section and Figure 40 ....................... 32
Changes to Figure 41 ...................................................................... 33
Changes to Writing Data over the I
2
C Bus Section .................... 34
Changes to Figure 44 ...................................................................... 35
Updated Outline Dimensions ....................................................... 37
Changes to Ordering Guide. ......................................................... 38
10/08—Revision 0: Initial Version