ak4184a AKM Semiconductor, Inc., ak4184a Datasheet - Page 30

• Manufacturer Part Number: ak4184a
• Description: Tsc With Keypad Scanner And Gpio Expander
• Manufacturer: AKM Semiconductor, Inc.

Figure 18
which demonstrates the optimum layout and power supply arrangement.
■
The AK4184A requires careful attention to power and grounding. VSS1, VSS2 must be connected to analog ground
system analog ground and digital ground must be connected together as close as possible to where the supplies are
brought onto the printed circuit board. Decoupling capacitors must be as close to the AK4184A as possible, with the
small value ceramic capacitor being the closest.
When an EMI source is close to the touch panel analog signal line, EMI noise reduces analog performance
characteristics. Noise canceling capacitors as close as possible to each pin (XP, XN, YP, YN pins) of the AK4184A
should be connected to avoid this noise.
printed circuit board for countermeasure for surge and static electricity on the touch panel, GPIO and keypad signal
lines.
MS0947-E-00
Digital I/O Supply
Attention to the PCB wiring
Keypad
1.6∼AVDD
Note:
- The DOUT pin is floating except when communicating with the host processor. A 100kΩ pull-down or
- VSS1 and VSS2 of the AK4184A must be distributed separately from the ground of external controllers.
- Do not allow digital input pins (CSN, SCLK, DIN pins) to float.
6 x 5
shows a system connection diagram for the AK4184A. The evaluation board [AKD4184A] is available,
pull-up register must be connected.
+
10µ
0.1µ
IOVDD
VSS2
Figure 18. Typical connection diagram
NC
C1
NC
R4
(Figure
R3
KEYIRQN
C3
C2
R2
R1
C4
R5
SYSTEM DESIGN
18) In addition, ESD protection devices should be mounted on the
BUSY
VSS2
DOUT
C5
C6
Top View
LED Driver
BRCONT
µP
SCLK RESETN
GP0
DIN
- 30 -
GP1
GP2
CSN
GP5
XP
XN
IRQN
VSS1
GP7
PEN
GP3
AVDD
GP4
GP6
NC
YP
YN
NC
0.1µ
0.01µ*
0.01µ*
0.01µ*
0.01µ*
Touch Screen
GPIO
4-wire
+
10µ
[AK4184A]
Analog Supply
2.5∼3.6V
2008/04