AK4183_08 Datasheet, PDF (13/18 Pages) Asahi Kasei Microsystems – I2C Touch Screen Controller

[AK4183]
■ Power-down Control
A/D converter and power-down control of touch driver switch are determined by PD0 bit.
PD0 PENIRQN
Function
0
Enabled Auto power-down Mode
A/D converter is automatically powered up at the start of the conversion, and goes to
power- down state automatically at the end of the conversion. 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 sampling time and conversion time.
1
Disabled ADC ON Mode
When X-axis or Y-axis are selected on the write operation with PD0 = “1” A/D
converter and touch panel driver are always powered up until next conversion. This
mode is effective if more settling time is required to suppress the electrical bouncing of
touch plate.
PEN interrupt function is disabled and PENIRQN is forced to “L” state
Table 4 Powers –Down Control
■ WRITE Operation Sequence (Figure 13)
The selection of channel input of AK4183 is determined by a command byte. The timing of the driver switch on is 18^th
falling edge of SCL regardless PD0 bit when accelerate command (A2= “0”) is sent. The accelerate command is to
accelerate the timing of desired driver SW ON to ensure that AK4183 needs more settling time. As for actually
sampling is on the time of READ operation, it becomes possible to take settling time long even when the impedance of
the touch screen is large.
SCL
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
SDA
Address Byte
Command Byte
R/ W
100
1
0
0 CAD0 0
0
S A2
A1 A0 X1 PD0 MODE X2
0
START
Touch Driver SW
A2=0, PD0=0 or 1
A2=1, PD0=1
AK4183
ACK
AK4183
ACK _STOP
A2=1, PD0=0
I
II
III
IV
Figure 13 write operation and Driver SW timing
MS0500-E-01
13
2008/12