ak4184 AKM Semiconductor, Inc., ak4184 Datasheet - Page 30

• Manufacturer Part Number: ak4184
• Description: Tsc With Keypad Scanner And Gpio Expander
• Manufacturer: AKM Semiconductor, Inc.

Figure 17 shows a system connection diagram for the AK4184. The evaluation board [AKD4184] is available, which
demonstrates the optimum layout and power supply arrangement.
L
The AK4184 requires careful attention to power and grounding. VSS1, VSS2 should be connected to analog ground
system analog ground and digital ground should be connected together as close as possible to where the supplies are
brought onto the printed circuit board. Decoupling capacitors should be as close to the AK4184 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 AK4184 to
avoid this noise. (Figure 17)
MS0603-E-00
Digital I/O Supply
Attention to the PCB wiring
Keypad
1.6 AVDD
Note:
- VSS1 and VSS2 of the AK4184 should be distributed separately from the ground of external controllers.
- Do not allow digital input pins (CSN, SCLK, DIN pins) to float.
-The DOUT pin is floating except when communicating with the host processor. A 100k pull-down or pull-
up register should be connected.
6 x 5
x x x x x x x x x x
x x x x x x x x x x
x x x x x x x x x x
x x x x x x x x x x
x x x x x x x x x x
x x x x x x x x x x
+
10µ
0.1µ
Figure 17. Typical connection diagram
IOVDD
VSS2
NC
C1
NC
R4
R3
KEYIRQN
C2
C3
C4
R2
R1
SYSTEM DESIGN
R5
BUSY
VSS2
DOUT
C5
C6
Top View
LED Driver
BRCONT
µP
SCLK RESETN
GP0
DIN
30
GP1
GP2
CSN
GP5
XP
XN
IRQN
VSS1
GP3
GP7
PEN
AVDD
GP4
GP6
NC
YP
YN
NC
0.1µ
0.01µ*
0.01µ*
0.01µ*
0.01µ*
Touch Screen
GPIO
4-wire
x x x x x x x x x
x x x x x x x x x
x x x x x x x x x
x x x x x x x x x
x x x x x x x x x
+
10µ
2007/04
[AK4184]
Analog Supply
2.5 3.6V