Specifications

Touch Controllers Reference Guide112
Layout of the System Board
Figure 7 shows some typical techniques for two layer boards. The
same techniques apply to four layer boards except that the various
planes may be put on inner layers.
To design the Daughterboard controller onto the system board and to
ensure optimal operation, follow these guidelines:
A. Route the shield signal (Pin 8) and the corner drive lines
(Pin 9-UR, Pin 10-LR, Pin 11-UL, Pin 12-LL) on the component
side. Keep the shield connection (Pin 8) and the four corner runs
(Pins 9 – 12) away from all other runs on the board.
B. Design locking posts onto the system board to hold the board in
place. If you use non-insulating locking posts, make sure you
connect the posts to signal ground.
C. Keep the ground and power etches (or planes) as short and as low
impedance as possible.
D. Keep the runs from the touchscreen connector to the
Daughterboard connector as short as possible. The connections
from Pins 1 – 12 on the touchscreen connector to Pins 1 – 12 on
the Daughterboard connector are 1-to-1. Keep the four corner
runs and the shield connection (Pins 8 – 12) away from all other
runs on the board.
E. Connect the diodes as shown in the Inset A-A diagram. Connect
the VCC (+5 V) and the chassis ground to the diodes. Place the
diodes as close as possible to the touchscreen connector on the
system board.
F. Make sure you keep the other runs from the touchscreen
connector away from the four corner and shield runs. Be sure the
CMOS connections for receive and transmit (Pin 13 and Pin 14)
are routed away from the four corner runs and the shield signal.