GMS90C31 datasheet(28/59 Pages) HYNIX

28 / 59 page

GMS90 Series

Oct. 2000 Ver 3.1a

Power Saving Modes

Two power down modes are available, the Idle Mode and Power Down Mode.

The bits PDE and IDLE of the register PCON select the Power Down mode or the Idle mode, respectively. If

the Power Down mode and the Idle mode are set at the same time, the Power Down mode takes precedence.

Table 10 gives a general overview of the power saving modes.

In the Power Down mode of operation, VCC can be reduced to minimize power consumption. It must be ensured,

however, that VCC is not reduced before the Power Down mode is invoked, and that VCC is restored to its normal

operating level, before the Power Down mode is terminated. The reset signal that terminates the Power Down

mode also restarts the oscillator. The reset should not be activated before VCC is restored to its normal operating

level and must be held active long enough to allow the oscillator to restart and stabilize (similar to power-on

reset).

Table 10. Power Saving Modes Overview

Mode

Entering

Instruction

Example

Leaving by

Remarks

Idle mode

ORL PCON, #01H

- Enabled interrupt

- Hardware Reset

CPU is gated off

CPU status registers maintain their

data.

Peripherals are active

Power-Down mode

ORL PCON, #02H

Hardware Reset

Oscillator is stopped, contents of on-

chip RAM and SFR’s are maintained

(leaving Power Down Mode means

redefinition of SFR contents).

GMS90C31 데이터시트(PDF) 28 Page - Hynix Semiconductor