
[AK4673] 
MS0670-E-00 
2007/09 
- 78 - 
■
 Pen Interrupt 
The AK4673 has a pen-interrupt function to detect the pen touch on the touch panel. This function will be used as the 
interrupt of the microprocessor. Pen interrupt function is enabled at power-down state. YN driver is on and this pin is 
connected to GND at the power down state. And the XP pin is pulled up via an internal resister (Ri), typically 10K
Ω
. If 
the touch plate is touched by pen or stylus, the current flows via <VCC>-<Ri>-<XP>-<the plates>-<YN>-<GND>. The 
resistance of the plate is generally 1K
Ω
 or less, the PENIQRN pin is force to “L” level. If the pen is released, the 
PENIRQN pin returns “H” level because two plates are disconnected, and the current does not flow via two plates. 
The transition of PENIRQN is related to PD0 bit. PD0 bit is updated as shown below. (Please see “power-down control” 
for the detail. Once the control command PD0= “1” is sent the pen-interrupt function is disabled.  
The clock number under the write and the read operation refer to 
Figure 74
 and 
Figure 14
. 
I.
The period from start condition to SCL7
↓
The level transition of the PENIRQN pin is determined by PD0 bit of the previous command. When the previous 
command with PD0= “0” the pen-interrupt function will be enabled. The PENIRQN pin is low when the panel is 
touch, the PENIRQN pin is “H” when the panel is untouched.  When the previous command with PD0= “1” is 
sent PENIRQN pin is low regardless of pen-touch  
II.
The period SCL7
↓
 to SCL8
↑
 on the write operation 
The level of the PENIRQN pin is always low regardless of PD0 bit and the state of panel (touched/untouched)  
III.
The period from  SCL8
↑
 to SCL18
↓
  on the write operation 
The level transition of the PENIRQN pin is determined by PD0 bit of the previous command. When the previous 
command with PD0= “0” the pen-interrupt function will be enabled. The PENIRQN pin is low when the panel is 
touch, the PENIRQN pin is “H” when the panel is untouched.  When the previous command with PD0= “1” is 
sent PENIRQN pin is low regardless of pen-touch 
IV.
The period from SCL18
↓
 on the write operation to SCL7
↓
 on the read operation 
The level of PENIRQN pin is determined by the A2 bit and PD0 bit of the present command. The PENIRQN pin 
is always low regardless pen-touch when command with A2 = “1” or PD0 = “1” is set. The PENIRQN is 
determined by the pen-touch (touched/untouched) when command with A2= “1” and PD0= “1” is sent. 
V.
The period from SCL7
↓
 to SCL21
↓
 on the write operation 
The AD input will sample the hold and the conversion will be done during this period. PENIRQN is always low. 
VI.
The period after SCL21
↓
 on the read operation 
The level transition of the PENIRQN pin is determined by PD0 bit of the present command. When the present 
command PD0= “0” is sent the pen-interrupt function will be enabled. The PENIRQN pin is low when the panel 
is touched. The PENIRQN pin is “H” when the panel is untouched.  When the present command PD0= “1” are 
sent the PENIRQN pin is low regardless of pen-touch.  
It is recommended that the processor will mask the pseudo interrupt while the control command is issued or AD data is 
sent to processor. 
XP 
PENIRQN 
Driver ON
YN 
EN2 
Ri = 
10k
Ω
Driver OFF
EN1 
VCC 
VCC 
VCC
PEN Interrupt
To uP 
Figure 76 Pen interrupt function block