26
EPSON
S1C63358 TECHNICAL MANUAL
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Setting of Power Supply and Operating Mode)
VADSEL: Power supply selection register for A/D converter voltage circuit (FF01H•D3)
Selects the power supply for the A/D converter voltage circuit.
When "1" is written: V
C2
When "0" is written: V
DD
Reading: Valid
When "1" is written to the VADSEL register, the A/D converter voltage circuit enters the V
C2
mode and
operates with V
C2
output from the LCD booster. When "0" is written to the VADSEL register, the A/D
converter voltage circuit operates with V
DD
and the operating mode becomes the normal mode.
When switching from the normal mode to the V
C2
mode, the VADSEL register should be set to "1" after
taking a 100 msec or longer interval for the V
C2
to stabilize from setting the LPWR register to "1".
At initial reset, this register is set to "0".
When using the A/D converter with a 1.6 V or less power supply voltage, set the V
C2
mode.
4.2.6 Programming notes
(1) When operating the S1C63358 with a 0.9–1.4 V power supply voltage, software control is necessary.
Set the oscillation system voltage regulator to the V
C2
mode. When 1.4 V or more power supply
voltage is used, don't set the oscillation system voltage regulator into the V
C2
mode.
(2) When using the A/D converter with a 0.9–1.6 V power supply voltage, software control is necessary.
Set the A/D converter voltage circuit to the V
C2
mode. When 1.6 V or more power supply voltage is
used, don't set the A/D converter circuit into the V
C2
mode.
(3) If the power supply voltage is out of the specified voltage range for an operating mode, do not switch
to the operating mode. It may cause malfunction or increase current consumption.
(4) When switching from the normal mode to the V
C2
mode, the VDSEL and/or VADSEL registers should
be set to "1" after taking a 100 msec or longer interval for the V
C2
to stabilize from switching the
LPWR register to "1".
(5) When switching from the V
C2
mode to the normal mode, use separate instructions to switch the mode
(VDSEL = "0" or VADSEL = "0") and turn the LCD booster OFF (LPWR = "0", if LCD is unused).
Simultaneous processing with a single instruction may cause malfunction.
(6) The OSC3 oscillation circuit can operate only in the normal mode with a power supply voltage from
2.3 V to 3.6 V.