ak4182 AKM Semiconductor, Inc., ak4182 Datasheet - Page 14

• Manufacturer Part Number: ak4182
• Description: Touch Screen Controllers
• Manufacturer: AKM Semiconductor, Inc.

ASAHI KASEI
The AK4182 has pen interrupt function to detect the pen touch. Pen interrupt function is enabled at power-down state. YN pin is
connected to GND at the PEN interrupt enabled state. And XP pin is pulled up via an internal resistor (Ri), typically 50k Ω . If
touch plate is pressed by pen, the current flows via <VCC> – <Ri> – <XP> –<the plates> - <YN>- <GND>. The resistance of the
plate is generally 1K Ω or less, PENIRQN is forced to “L” level. If the pen is released, PENIRQN returns “H” level because two
plates are disconnected, and the current doesn’t flow via two plates.
If the plate is touched with pen or finger, PENIRQN goes to “L” at CSN = “H” unless previous command issued with both PD1
and PD0 is “1”. PENIRQN is disabled and keeps “H” level regardless of the touched/non-touched state if CSN = “H”.
The operation of PENIRQN is related to PD0 bit. PD0 bit is updated at the rising edge of 8th DCLK (please see “ Power-down
Control” for the detail). Therefore, the last PD0 bit is valid until this timing. (The internal voltage reference is controlled by only
PD1 bit regardless of PD0 bit and CSN state.)
i.
The behavior of PENIRQN is related to the combination of the last selected analog input channel, and the last PD0 bit. If the last
PD0 bit was set to “0”, PENIRQN is “H” while the plate is not pressed and “L while the plate is pressed regardless of the last
analog input. If the last PD0 bit was set to “1”, the last analog input decides the level of PENIRQN. If the last analog input
channel is ether X-axis or Y-axis, PENIRQN is “L” for all the time in this period regardless of the touched/non-touched state. On
the other hand, if the last analog input is temperature, VBAT, or auxiliary inputs, PENIRQN is “H” for all the time in this period
regardless of the touched/non-touched state.
ii.
iii.
It is recommended that the micro controller mask the pseudo-interrupts while the control command is issued or A/D data is output.
MS0411-E-00
Pen Interrupt
The behavior of PENIRQN is related to the selected analog input. If the X-axis or Y-axis is selected as analog input, PENIRQN
is forced to “L” regardless of the touched/non-touched state. If the temperature, VBAT, or auxiliary inputs is selected,
PENIRQN is forced to “H” regardless of the touched/non-touched state.
The behavior of PENIRQN is related to the combination of the current selected analog input channel, and the current PD0 bit.
If the current PD0 bit is set to “0”, PENIRQN is “H” while the plate is not pressed and “L while the plate is pressed regardless
of the current selected analog input. If the current PD0 bit is set to “1”, the current analog input decides the operation of
PENIRQN. If the current analog input channel is ether X-axis or Y-axis, PENIRQN is “L” for all the time in this period
regardless of the touched/non-touched state. On the other hand, if the current analog input is temperature, VBAT, or auxiliary
inputs, PENIRQN is “H” for all the time in this period regardless of the touched/non-touched state.
The period from CSN↓ to the 5th DCLK.
The period from the 5th DCLK↓ to the 20th DCLK↓ on CSN = “L"
The period from the 20th DCLK↓ to CSN↑
EN1
IOVDD
Figure 8 PENIRQ Functional Block Diagram
50kΩ
Ri =
VCC
EN2
14
Driver OFF
Driver ON
VCC
XP
YN
PENIRQN
2005/08
[AK4182]