SM5953
8-Bit Micro-controller
15KB with ISP Flash
& 256B RAM embedded
11. Power Management Unit
Power management unit serves two power management modes, Idle and Power Down, for the users to do power
saving function.
Mnemonic: PCON
Address: 87h
7
6
-
5
-
4
-
3
GF1
2
GF0
1
PD
0
IDLE
Reset
00h
SMOD
GF1: General-purpose flag bit.
GF0: General-purpose flag bit.
PD: Power Down mode control bit. Setting this bit turning on the PD Mode.
PD bit is always read as 0
IDLE: Idle mode control bit. Setting this bit turning on the Idle Mode.
Idle bit is always read as 0
11.1 Idle mode
An instruction that sets PCON.0 causes that to be the last instruction executed before going into the idle mode, the
internal clock is gated off to the CPU but not to the interrupt, timer and serial port functions.
There are two ways to terminate the idle. Activation of any enabled interrupt will cause PCON.0 to be cleared by
hardware, terminating the idle mode. The interrupt will be serviced, and following RETI, the next instruction to be
executed will be the one following the instruction that put the device into idle. Another way to wake-up from idle is
to pull RESET high to generate internal hardware reset.
11.2 Power Down mode
An instruction that sets PCON.1 cause that to be the last instruction executed before going into the Power-Down
mode. In the power-down mode, the on-chip oscillator is stopped. The contents of on-chip RAM and SFRs are
maintained. Be carefully to keep RESET pin active for at least 10ms in order for a stable clock.
The power-down mode can be woken-up by RESET pin. When it is woken-up by RESET, the program will execute
from the address 0000H.
Pin Status in IDLE Mode and Power-Down Mode
Mode
Program Memory
Internal
ALE
PSEN
Port0
Data
Float
Data
Float
Port1
Data
Data
Data
Data
Port2
Data
Address
Data
Port3
Data
Data
Data
Data
Idle
Idle
1
1
0
0
1
1
0
0
External
Internal
External
Power-Down
Power-Down
Data
Specifications subject to change without notice contact your sales representatives for the most recent information.
ISSFD-M074 Ver B SM5953 12/27/2013
- 37 -
SYNCMOS [ SYNCMOS TECHNOLOGIES,INC ]
