AD7879 datasheet(35/36 Pages) AD

35 / 36 page

AD7879

Rev. 0 | Page 35 of 36

GROUNDING AND LAYOUT

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-

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.

NC = NO CONNECT

Y+

X–

DOUT

AD7879

PENIRQ/INT/DAV

TOUCH

SCREEN

0.1µF

0.1µF TO 10µF

(OPTIONAL)

VOLTAGE

REGULATOR

MAIN

BATTERY

INT

SCLK

MISO

MOSI

HOST

Figure 45. Typical Application Circuit

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