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CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Setting of Power Supply and Operating Mode)
Power supply
circuit
Oscillation system
voltage regulator
* Set the V
heavy load operation (driving buzzer or lamp) or by battery deletion.
(1) Power supply voltage V
When the power supply voltage is in this range, the oscillation system voltage regulator can operate
only in the V
mode.
C2
Set the V
mode with software, and do not change it to another mode during operation.
C2
(2) Power supply voltage V
When the CPU operates with the OSC1 clock (OSC3 oscillation circuit is OFF), the oscillation system
voltage regulator can operate in the normal mode. Be sure not to set in the V
(3) Power supply voltage V
When the power supply voltage is in this range, the oscillation system voltage regulator can always
operate in the normal mode regardless of the oscillation circuit setting. Be sure not to set in the V
mode.
The OSC3 oscillation circuit can be used in this voltage range.
4.2.3 Operating mode for LCD system voltage circuit
The LCD system voltage circuit generates the voltage V
system voltage circuit generates V
Turning the LCD power supply circuit ON/OFF can be controlled using the register LPWR. The LCD
drive voltage is output to the LCD driver only when the circuit is ON (LPWR = "1").
(1) Power supply voltage V
When the power supply voltage is in this range, the V
LCD display contrast will become worse.
(2) Power supply voltage V
When the power supply voltage is in this range, the V
will keep the same contrast.
4.2.4 Operating mode for A/D converter voltage circuit
The A/D converter uses AV
(1) Power supply voltage V
When the power supply voltage is in this range, it is possible to operate in the normal mode. Be sure
not set in the V
mode.
C2
(2) Power supply voltage V
When the power supply voltage is in this range, VADSEL should be set to "1", to choose V
A/D converter power.
24
Table 4.2.2.1 Power supply voltage and operating mode
Operating
Operating
condition
voltage V
OSC1
OSC3, 4 MHz
mode when a supply voltage drop is detected by the SVD circuit, such as during a
C2
= 0.9 V to 1.4 V
DD
= 1.4 V to 2.3 V
DD
= 2.3 V to 3.6 V
DD
by the regulator, and boosts it to generate the other 2 voltages.
C1
= 0.9 V to 1.4 V
DD
= 1.4 V to 3.6 V
DD
and V
or V
DD
DD
C2
Table 4.2.4.1 Power supply voltage and operating mode
Circuit
A/D converter
= 1.6 V to 3.6 V
DD
= 0.9 V to 1.6 V
DD
Power supply voltage V
0.9–1.4
D1
1.35 V
V
mode
C2
2.25 V
Cannot work
, V
and V
C1
C2
voltage will follow the V
C1
voltage will keep 1.05 V, so the LCD display
C1
as the power source for internal control circuit.
Power supply voltage V
0.9–1.6
1.6–3.6
V
mode
Normal mode
C2
EPSON
(V)
DD
1.4–2.3
2.3–3.6
Normal mode ∗
Normal mode
mode.
C2
for driving the LCD. The LCD
C3
voltage, so the
DD
(V)
DD
S1C63358 TECHNICAL MANUAL
C2
as the
C2
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