S i M 3 U 1 x x
38
Preliminary Rev. 0.8
4.1.5. Device Power Modes
The SiM3U1xx devices feature four low power modes in addition to normal operating mode. Several peripherals
provide wake up sources for these low power modes, including the Low-Power Timer (LPT0), RTC0 (alarms and
oscillator failure notification), Comparator 0, and PMU Pin Wake. All power modes are detailed in Table 4.1.
In addition, all peripherals can have their clocks disconnected to reduce power consumption whenever a peripheral
is not being used using the clock control (CLKCTRL) registers.
Table 4.1. SiM3U1xx Power Modes
Mode
Description
Mode Entrance
Mode Exit
Normal
Core operating at full
speed
Code executing from
Flash
Power Mode 1
(PM1)
Core operating at full
speed
Code executing from
RAM
Execute code from RAM
Jump to code in Flash
Power Mode 2
(PM2)
Core halted
AHB and APB operate
at full speed for
peripherals
WFI or WFE instruction
NVIC or WIC wakeup
Power Mode 3
Fast Wake
(PM3FW)
All clocks stopped
except LFOSC0 or
RTC0OSC
AHB and APB set to
Low Power Oscillator
Core clock set to
LFOSC0 or RTC0OSC
DMACTRL0
disabled
Fast wake mode
enabled in PM3CN
AHB switched to
Low Power
Oscillator
WFI or WFE
instruction
NVIC or WIC wakeup
Power Mode 3
(PM3)
All clocks stopped
DMACTRL0
disabled
Clocks disabled in
PM3CN
WFI or WFE
instruction
NVIC or WIC wakeup
Power Mode 9
(PM9)
Low power shutdown
SLEEPDEEP set in
the ARM System
Control Register
WFI or WFE
instruction
Requires a reset defined by
the PMU as a wake up
source