Operations - Epson S1C17W18 Technical Manual

2 POWER SUPPLY, RESET, AND CLOCKS

2.1.3 Operations

PWG2 provides four operating modes listed in Table 2.1.3.1.
Operating mode Power consumption
Normal mode
Automatic mode
Economy mode
Super economy mode
*1 For the V voltage range to set super economy mode, refer to "Recommended Operating Conditions, Power
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supply voltage V " in the "Electrical Characteristics" chapter.
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Normal mode
Using this mode results in the highest power consumption within the four operating modes, however, it pro-
vides high-stability operations without being affected by voltage fluctuations.
Switching to normal mode from another mode (economy mode)
1. Write 0x0096 to the MSCPROT.PROT[15:0] bits.
2. Set the PWGCTL.PWGMOD[2:0] bits to 0x2.
3. Write a value other than 0x0096 to the MSCPROT.PROT[15:0] bits. (Set system protection)
Economy mode
PWG2 performs power-saving operations. Power consumption can be reduced in comparison with normal
mode. However, this mode can be set only when the system is under light load conditions (see "Condition of
use" for economy mode in Table 2.1.3.1) because of its lack of V
does not allow use of high-speed clocks (IOSC, OSC3, and EXOSC).
Switching to economy mode from another mode (normal mode)
1. Write 0x0096 to the MSCPROT.PROT[15:0] bits.
2. Check to see if the OSC1 oscillation has stabilized (see "Oscillation start procedure for the OSC1 oscil-
lator circuit" in Section 2.3.4.).
3. Stop the high-speed clock sources.
4. Set the PWGCTL.PWGMOD[2:0] bits to 0x3.
5. Write a value other than 0x0096 to the MSCPROT.PROT[15:0] bits. (Set system protection)
Note: Be sure to avoid switching to economy mode while a high-speed clock source is operating, as it
may cause a malfunction.
Automatic mode
In this mode, the hardware automatically switches between normal mode and economy mode as described
above. Use PWG2 in automatic mode when no special control is required.
Switching to automatic mode from another mode
1. Write 0x0096 to the MSCPROT.PROT[15:0] bits.
2. Set the PWGCTL.PWGMOD[2:0] bits to 0x0.
3. Write a value other than 0x0096 to the MSCPROT.PROT[15:0] bits. (Set system protection)
The following shows the conditions for the hardware to switch between normal mode and economy mode and
its operations:
1. When all the clock sources except for OSC1 are stopped in normal mode
After a lapse of 1 ms from stop of the clock source, the hardware switches from normal mode to economy
mode and sets the PWGINTF.MODCMPIF bit to 1.
2. When a clock source other than OSC1 is started in economy mode
The hardware switches to normal mode at the same time the clock source is started.
2-2
Table 2.1.3.1 PWG2 Operating Mode
High None
None
↑
All the clock sources except for OSC1 are halted (RUN, HALT, or SLEEP mode) or all
the clock sources are halted (SLEEP mode).
1) V meets the voltage requirement.
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2) OSC1 is operating with stability and all other clock sources are halted (when OSC1
↓
Low
is not configured to halt in RUN, HALT, or SLEEP mode).
Seiko Epson Corporation
Conditions of use
*1
(Remove system protection)
(Set to normal mode)
drive capability. Therefore, economy mode
D1
(Remove system protection)
(Set to economy mode)
(Remove system protection)
(Set to automatic mode)
S1C17W18 TECHNICAL MANUAL
(Rev. 1.2)