Appendix B Power Saving; Operating Status Configuration Examples For Power Saving - Epson S1C17F13 Technical Manual

Appendix B Power Saving

Current consumption will vary dramatically, depending on CPU operating mode, operation clock frequency, pe-
ripheral circuits being operated, and V
power.
B.1

Operating Status Configuration Examples for Power Saving

Table B.1.1 lists typical examples of operating status configuration with consideration given to power saving.
Operating status
configuration
Standby
Clock counting
Low-speed processing
Peripheral circuit operations
High-speed processing
If the current consumption order by the operating status configuration shown in Table B.1.1 is different from one
that is listed in "Electrical Characteristics," check the settings shown below.
PWGVD1CTL.REGMODE[1:0] bits of the power generator
If the PWGVD1CTL.REGMODE[1:0] bits of the power generator is 0x2 (normal mode) when the CPU enters
SLEEP mode, current consumption in SLEEP mode will be larger than I
Characteristics." Set the PWGVD1CTL.REGMODE[1:0] bits to 0x3 (economy mode) or 0x0 (automatic mode)
before executing the slp instruction.
CLGOSC. xxxxSLPC bits of the clock generator
Setting the CLGOSC.OSC3BSLPC, OSC3ASLPC, OSC1SLPC, or EXOSCSLPC bit of the clock generator to
0 disables the oscillator circuit stop control when the slp instruction is executed. To stop the oscillator circuits
during SLEEP mode, set these bits to 1.
MODEN bits of the peripheral circuits
Setting the MODEN bit of each peripheral circuit to 1 starts supplying the operating clock enabling the periph-
eral circuit to operate. To reduce current consumption, set the MODEN bits of unnecessary peripheral circuits to 0.
External components for OSC1A oscillator circuit
External components for the OSC1A oscillator circuit affect current consumption.
• Using lower OSC1A external gate and drain capacitances decreases current consumption.
• Using a crystal resonator with lower C
However, these selections may reduce the oscillation margin and increase the frequency error, therefore, be sure
to perform matching evaluation using the actual printed circuit board.
OSC3A oscillator circuit configurations
The OSC3A oscillator circuit provides some configuration items to support various crystal and ceramic resona-
tors. These configurations trade off current consumption for performance as shown below.
• The lower oscillation inverter gain setting (CLGOSC3A.INVN[1:0] bits) decreases current consumption.
• Using lower OSC3A external gate and drain capacitances decreases current consumption.
• Using a resonator with lower C
However, these configurations may reduce the oscillation margin and increase the frequency error, therefore, be
sure to perform matching evaluation using the actual printed circuit board.
S1C17F13 TeChniCal Manual
(Rev. 1.0)
regulator operating mode. Listed below are the control methods for saving
D1
Table B. 1.1 Typical Operating Status Configuration Examples
Current
V OSC1
D1
consumption
OFF
↑
Economy
Low
ON
High
Normal
↓
value decreases current consumption.
L
value decreases current consumption.
L
Seiko epson Corporation
APPENDIX B POWER SAVING
OSC3A/
OSC3B/ RTC CPU
EXOSC
OFF SLEEP
SLEEP
OFF
HALT
OSC1 RUN
ON
SLEEP or HALT
OSC3A/OSC3B/
ON
EXOSC RUN
or I
SLP1 SLP2
Current consumption
listed in electrical
characteristics
I
SLP1
I
SLP2
I
HALT2
I
RUN20
I
HALT1
I
RUN10
that is listed in "Electrical
aP-B-1