SN8P2977
8-Bit Micro-Controller with Regulator, PGIA, 24-bit ADC
SONiX TECHNOLOGY CO., LTD
Page 54
Version 1.7
5.3 WAKEUP
5.3.1
OVERVIEW
Under power down mode (sleep mode) or green mode, program doesn
’t execute. The wakeup trigger can wake the
system up to normal mode or slow mode. The wakeup trigger sources are external trigger (P0 level change) and
internal trigger (T0 timer overflow and ADC conversion complete).
Power down mode is waked up to normal mode. The wakeup trigger is only external trigger (P0 level change)
Green mode is waked up to last mode (normal mode or slow mode). The wakeup triggers are external trigger (P0
level change) and internal trigger (T0 timer overflow and ADC conversion complete).
5.3.2
WAKEUP TIME
When the system is in power down mode (sleep mode), the high clock oscillator stops. When waked up from power
down mode, MCU waits for 64 internal high-speed RC oscillator (IHRC) clocks as the wakeup time to stable the
oscillator circuit. After the wakeup time, the system goes into the normal mode.
Note: Wakeup from green mode is no wakeup time because the clock
doesn’t stop in green mode.
The value of the power down wakeup time is as the following.
The Wakeup time = 1/Fhosc * 64 (sec) + high clock start-up time
Note: The high clock start-up time is depended on the VDD. In general, high clock start-up time will be
several micro-second (us) at VDD=3V.
Example: The system is waked up from power down (sleep mode) by P0 level chande. After the
wakeup time, the system goes into normal mode. The wakeup time is as the following.
The wakeup time = 1/Fhosc * 64 = 8us
(Fhosc = 8MHz)
The total wakeup time = 8us + oscillator start-up time (5us)