ad7879-1acbz-rl Analog Devices, Inc., ad7879-1acbz-rl Datasheet - Page 35

• Manufacturer Part Number: ad7879-1acbz-rl
• Description: Low Voltage Controller For Touch Screens
• Manufacturer: Analog Devices, Inc.

For detailed information on grounding and layout considera-
tions for the AD7879, refer to the AN-577 Application Note,
Layout and Grounding Recommendations for Touch Screen
Digitizers.
CHIP SCALE PACKAGES
The lands on the chip scale package (CP-16-10) are rectangular.
The printed circuit board (PCB) pad for these should be 0.1 mm
longer than the package land length, and 0.05 mm wider than
the package land width. Center the land on the pad to maximize
the solder joint size.
The bottom of the chip scale package has a central thermal pad.
The thermal pad on the printed circuit board should be at least
as large as this exposed pad. To avoid shorting, provide a clear-
GROUNDING AND LAYOUT
SCREEN
TOUCH
NC = NO CONNECT
1
2
3
4
NC
NC
Y+
X–
Figure 45. Typical Application Circuit
AD7879
PENIRQ/INT/DAV
Rev. 0 | Page 35 of 36
0.1µF
DOUT
NC
NC
ance of at least 0.25 mm between the thermal pad and the inner
edges of the land pattern on the PCB. Thermal vias can be
used on the printed circuit board thermal pad to improve thermal
performance of the package. If vias are used, they should be
incorporated in the thermal pad at a 1.2 mm pitch grid. The via
diameter should be between 0.3 mm and 0.33 mm, and the via
barrel should be plated with 1 oz. of copper to plug the via.
Connect the PCB thermal pad to GND.
WLCSP ASSEMBLY CONSIDERATIONS
For detailed information on the WLCSP PCB assembly and
reliability, see the AN-617 Application Note, MicroCSP™ Wafer
Level Chip Scale Package.
12
11
10
9
0.1µF TO 10µF
(OPTIONAL)
CS
INT
SCLK
MISO
MOSI
REGULATOR
VOLTAGE
HOST
MAIN
BATTERY
AD7879