ak4184a AKM Semiconductor, Inc., ak4184a Datasheet - Page 19

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

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The AK4184A has a pen interrupt function to detect a pen touch. The pen interrupt function is enabled during power-
down state. The YN pin is connected to GND during the pen interrupt enabled state. The XP pin is pulled up via an
internal resistor (Ri), typically 50kΩ. If the touch plate is pressed by a pen, the current flows via <AVDD> - <Ri> -
<XP> - <the plates> - <YN>- <GND>. The resistance of the plate is generally several hundreds, and PENIRQN pin
is forced to a “L” level. If the pen is released, the PENIRQN pin returns to a “H” level because two plates are
disconnected, and the current doesn’t flow between the two plates. The PENIRQN pin is a buffer type. The “H” level
is specified by IOVDD.
The operation of PENIRQN is related to PD bit. The pen interrupt function is disabled and stays “H” irrespective of
the pen touch when the PD bit is “1”. When the PD bit is “0”, the PENIRQN pin is forced “H” from the falling edge
of the sixth SCLK to the rising edge of CSN. The pen interrupt function is valid when the CSN pin is “H”. The
PENIRQN pin stays low when the touch panel is pressed, and stays high when the touch panel is not pressed.
The pen interrupt function is determined by the present PD bit setting when the host writes to or reads from the
register other than the pen touch block.
The touch panel block is able to power down when the TPPD bit is “1”
in this state and the pen interrupt function is not valid. The current through the touch screen does not flow even
through the panel is pressed.
MS0947-E-00
Pen Interrupt
IOVDD
Figure 10. PENIRQ Functional Block Diagram
50kΩ
Ri =
AVDD
EN
- 19 -
Driver OFF
Driver ON
(Table
AVDD
25). All the touch panel drivers turn off
XP
YN
PENIRQN
[AK4184A]
2008/04