
[ASAHI KASEI] 
[AK4180] 
<MS0195-E-01> 
 2003/02 
12 
 Power-down Control 
Power-down is controlled by two bits, PD0 bit and PD1 bit.  The power-down state of internal voltage reference is controlled by 
PD1 bit, and is updated at the rising edge of 7
 DCLK with CSN=”L”.   
The power-down state of  A/D converter, and touch screen driver switches is controlled by PD0 bit, and is updated at the rising 
edge of 8
 DCLK with CSN=”L”.  
If PD0 bit is set to “1”, the state of the driver switches is maintained until the 5
th
 DCLK
↑
 of the next conversion if CSN is “L”.  If 
CSN is “H”, all driver switches except for YN switch switches are turned off and are open states.  Only YN driver switch is turned 
ON and YN pin is forced to the ground in this case.   
PD1 
PD0 
PENIRQN 
0 
0 
Enabled 
Auto Power-down Mode.   
A/D converter is automatically powered up at the initiation of the conversion, and goes to power- 
down state automatically at the end of the conversion.  And the AK4180 is always powered down at 
this mode if CSN=”H”.   All touch screen driver switches except for YN switch are turned off and 
relative pins are open state.  Only YN driver switch is turned ON and YN pin is forced to the ground 
in this case.   PEN interrupt function is enabled except for the tracking time and conversion time even 
CSN=”L”.   Please see “
PEN Interrupt” 
for the detail.
 The internal voltage reference is always 
power-down state.  
0 
1 
Enabled 
ADC ON Mode 
A/D converter is always powered up while CSN = “L”.  The internal voltage reference is always 
power-down state.  if X-axis or Y axis is selected as analog input, touch screen driver switches are 
always turned ON and the current flows through the touch plate if CSN=”L”.  This is effective if  
more settling time for is required to suppress the electrical bouncing of touch plate.   
1 
0 
Enabled 
VREF ON Mode 
The internal voltage reference is always powered up regardless of CSN state.  ADC is auto power-
down mode.  PEN interrupt function is enabled at all the period except for the period from the 
5DCLK
↓
 to 20DCLK
↓
 regardless of CSN state.  
1 
1 
Disabled 
ADC and VREF ON Mode 
A/D converter and the internal voltage reference is power-up state   
PEN interrupt function is disabled and PENIRQN is forced to “H” state if CSN=”H”.  The behavior 
of PENIRQN is the same as “ADC ON Mode” 
Function 
Table  3  Power-down Control 
Serial Interface 
The AK4180 is controlled via 4-wire serial interface, CSN, DCLK, DIN, DOUT.   
Please see “
Switching Characteristics
” for the detail.  
CSN 
1 
2 
3 
4 
5 
SDFR   
BUSY
DOUT
S 
A2 
A0 
A1 
MO 
PD1 
PD0 
SDFR   
DCLK
DIN
11 
9 
8 
7 
6 
5 
4 
3 
2 
1 
0 
10 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
Driver SW 
SER/ DFR  =”1”
Driver SW 
SER/ DFR  =”0”
S 
A2 
A0 
A1 
MO 
PD1 
PD0 
11 
Hi-Z 
Hi-Z 
10 
Figure 5  Serial Interface