SS1102C datasheet(63/129 Pages) ETC1

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Power-Saving Modes

PRELIMINARY V1.8

13. Power-Saving Modes

13.1.

Overview

The MCU (Micro-Controller Unit) provides two kinds of methods to save power

consumption. The first method is to stop clock operations partially or wholly. The result

is to reduce switching current of CMOS. The other is to make pin status High-Z

(impedance). This feature will remove static current through resistors on board. Two

methods (clock control scheme and pin control scheme) can be combined together. The

Power-Saving Modes are controlled by the PSCR (Power-Saving Control Register) that

is an SFR (Special Function Register) mapped on memory address map. Any kind of

instruction, whose destination is the PSCR, can change the PSCR content. Thus, the

transitions of modes among normal and Power-Saving modes can be controlled by

software. In some cases, when CPU stops, hardware signals such like interrupts, an

IRQ1 Pin Event, and reset make the device change modes.

Figure 21.

Power Saving Modes & Transitions

Stabili-

zation

RESET

FastAll

!sstp:!fstp:!istp

SlowAll

!sstp:fstp:!istp

StopAll

sstp:fstp:!istp

FastPeri

!sstp:!fstp:istp

SlowPeri

!sstp:fstp:istp

S/W

Interrupt

S/W

Interrupt

S/W

IRQ1

Event

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