AK4185 AKM [Asahi Kasei Microsystems], AK4185 Datasheet - Page 25

• Manufacturer Part Number: AK4185
• Manufacturer: AKM [Asahi Kasei Microsystems]

<5-wire Touch Screen Input>
1. Grounding and Power Supply Decoupling
The AK4185 requires careful attention to power supply and grounding arrangements. VDD is usually supplied from the
system’s analog supply. VSS of the AK4185 must be connected to the analog ground plane. System analog ground and
digital ground should be connected together near to where the supplies are brought onto the printed circuit board.
Decoupling capacitors should be as near to the AK4185 as possible, with the small value ceramic capacitor being the
nearest.
2. Analog Inputs
When an EMI source is close to the touch panel analog signal line, EMI noise affects analog characteristics performance.
Connect noise canceling capacitors as close as possible to each pin (XP, XN, YP, YN pins) of the AK4185 to avoid this
noise.
MS0954-E-00
(Figure
Notes:
- The DOUT pin is floating except when communicating with the micro-controller. Therefore, a pull-up or
- VSS of the AK4185 should be distributed separately from the ground of external controllers.
- All digital input pins (CSN, SCLK, DIN pins) must not be left floating.
Analog Supply
pull-down resistor around 100kΩ must be connected to the DOUT pin of the AK4185.
24,
1.6∼3.6V
Figure
25)
10µ
+
Figure 25. Typical Connection Diagram
0.1µ
0.01µ *
WIPER
VDD
BR
Touch Screen
PENIRQN
5-wire
- 25 -
Top View
CSN
TR
DOUT
DIN
TL
SCLK
VSS
BL
Analog Ground
0.01µ *
0.01µ *
0.01µ *
0.01µ *
Digital Ground
µP
[AK4185]
2008/05