
5
POWER-DOWN CONTROL
S1C33L01 PRODUCT PART
EPSON
A-63
Function
Control bit
"1"
"0"
Default
System clock switch over
CLKCHG(D2)/
Power control register(0x40180)
OSC3 OSC1 OSC3
High-speed (OSC3) oscillation ON/OFF control
SOSC3(D1)/
Power control register(0x40180)
ON
OFF
ON
System clock division ratio selection
CLKDT(D[7:6])/
Power control register(0x40180)
"11" = 1/8
"10" = 1/4
"01" = 1/2
"00" = 1/1
1/1
Turning off the prescaler and peripheral circuits
Current consumption can be reduced by turning off the peripheral circuits operating at high speed as much as
possible. The circuits listed below are operated using a clock generated by the prescaler:
16-bit programmable timers 0 to 5 (watchdog timer)
8-bit programmable timers 0 to 3 (DRAM refresh, serial interface)
A/D converter
If none of these circuits need to be used, turn off the prescaler. If some of these circuits need to be used, turn off
all other unnecessary circuits and stop clock supply from the prescaler to those circuits.
Function
Control bit
"1"
"0"
Default
Prescaler ON/OFF
PSCON(D5)/Power control register(0x40180)
ON
OFF
ON
16-bit timer 0 clock control
P16TON0(D3)/16-bit timer 0 clock control register(0x40147)
ON
OFF
16-bit timer 0 Run/Stop
PRUN0(D0)/16-bit timer 0 control register(0x48186)
RUN
STOP
16-bit timer 1 clock control
P16TON1(D3)/16-bit timer 1 clock control register(0x40148)
ON
OFF
16-bit timer 1 Run/Stop
PRUN1(D0)/16-bit timer 1 control register(0x4818E)
RUN
STOP
16-bit timer 2 clock control
P16TON2(D3)/16-bit timer 2 clock control register(0x40149)
ON
OFF
16-bit timer 2 Run/Stop
PRUN2(D0)/16-bit timer 2 control register(0x48196)
RUN
STOP
16-bit timer 3 clock control
P16TON3(D3)/16-bit timer 3 clock control register(0x4014A)
ON
OFF
16-bit timer 3 Run/Stop
PRUN3(D0)/16-bit timer 3 control register(0x4819E)
RUN
STOP
16-bit timer 4 clock control
P16TON4(D3)/16-bit timer 4 clock control register(0x4014B)
ON
OFF
16-bit timer 4 Run/Stop
PRUN4(D0)/16-bit timer 4 control register(0x481A6)
RUN
STOP
16-bit timer 5 clock control
P16TON5(D3)/16-bit timer 5 clock control register(0x4014C)
ON
OFF
16-bit timer 5 Run/Stop
PRUN5(D0)/16-bit timer 5 control register(0x481AE)
RUN
STOP
8-bit timer 0 clock control
P8TON0(D3)/8-bit timer 0/1 clock control register(0x4014D)
ON
OFF
8-bit timer 0 Run/Stop
PTRUN0(D0)/8-bit timer 0 control register(0x40160)
RUN
STOP
8-bit timer 1 clock control
P8TON1(D7)/8-bit timer 0/1 clock control register(0x4014D)
ON
OFF
8-bit timer 1 Run/Stop
PTRUN1(D0)/8-bit timer 1 control register(0x40164)
RUN
STOP
8-bit timer 2 clock control
P8TON2(D3)/8-bit timer 2/3 clock control register(0x4014E)
ON
OFF
8-bit timer 2 Run/Stop
PTRUN2(D0)/8-bit timer 2 control register(0x40168)
RUN
STOP
8-bit timer 3 clock control
P8TON3(D7)/8-bit timer 2/3 clock control register(0x4014E)
ON
OFF
8-bit timer 3 Run/Stop
PTRUN3(D0)/8-bit timer 3 control register(0x4016C)
RUN
STOP
A/D converter clock control
PSONAD(D3)/A/D clock control register(0x4014F)
ON
OFF
A/D conversion enable
ADE(D2)/A/D enable register(0x40244)
RUN
STOP
The same clock source must be used for the prescaler operating clock and the CPU operating clock. Therefore,
when operating the CPU in low-speed with the OSC1 clock, the prescaler input clock must be switched
according to the CPU operating clock. In this case, in order to prevent a malfunction in the peripheral circuit,
the prescaler should be turned off before switching the CPU operating clock. After the CPU operating clock has
been switched, switch the prescaler operating clock and then turn the prescaler on.
Function
Control bit
"1"
"0"
Default
Prescaler operating clock
switch over
PSCDT0 (D0)/Prescaler clock select register(0x40181) OSC1 OSC3/
PLL
OSC3/
PLL