AK4184 Datasheet, PDF (17/36 Pages) Asahi Kasei Microsystems – TSC with Keypad Scanner and GPIO Expander

[AK4184]
■ Power-down Control
The power-down state of A/D converter and the touch screen driver switches is controlled by the PD bit.
PD PENIRQN
Function
0 Enabled Auto Driver Power Off Mode.
When PD bit is “0”, the touch screen driver switches and the A/D converter are
automatically powered up at the start of sampling, and moves to power- down state
automatically at the rising edge of CSN. The AK4184 is always powered down when
CSN is “H”. All touch screen driver switches except for the YN switch are turned off, and
relative pins are in an open state. Only the YN driver switch is turned ON, and the YN
pin is forced to ground. The pen interrupt function is enabled except when CSN is “L”.
See “„ Pen Interrupt” for detail.
1 Disabled ADC ON Mode
When PD bit is “1”, the touch screen driver switches and the A/D converter are always
turned ON. The pen interrupt function is disabled and the PENIRQN pin is always “H”,
regardless of the pen touch. The touch panel driver turns on before sampling time starts so
that the touch panel voltage fed into A/D converter is stable in this mode.
The sampling time starts at the falling edge of CSN this is effective if more settling time
is required to suppress the electrical bouncing of touch plate.
Table 8. Power-down Control
A/D converter is power-down both when CSN pin is “H” and controlling with keypad scanner, GPIO block, PWM
controller.
A/D converter is power-up when issues touch panel command at CSN pin is “L”.
MS0603-E-00
17
2007/04