Hyundai gms90x51c User Manual
GMS90X5XC Series
HYUNDAI MicroElectronics
Jan. 2001 Ver 1.0
23
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.
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, V
CC
can be reduced to minimize power consumption. It must be ensured,
however, that V
CC
is not reduced before the Power Down mode is invoked, and that V
CC
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 V
mode also restarts the oscillator. The reset should not be activated before V
CC
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).
reset).
Table 10. Power Saving Modes Overview
Mode
Entering
Instruction
Example
Leaving by
Remarks
Idle mode
ORL PCON, #01H
- Enabled interrupt
- Hardware Reset
- Hardware Reset
CPU is gated off
CPU status registers maintain their
data.
Peripherals are active
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).
chip RAM and SFR’s are maintained
(leaving Power Down Mode means
redefinition of SFR contents).