UM10850
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User manual
Rev. 2.4 — 13 September 2016
83 of 464
NXP Semiconductors
UM10850
Chapter 5: LPC5410x Power Management
5.3.5 Power-down mode
In Power-down mode, the system clock to the processor is disabled as in Sleep mode. All
analog blocks are powered down by default but can be selected to keep running if needed
for waking up the part. The main clock and all peripheral clocks are disabled except for the
clock to the watchdog timer if the watchdog oscillator is selected. The flash is powered
down, decreasing power consumption compared to Deep-sleep mode.
Power-down mode can eliminate all power used by analog peripherals and all dynamic
power used by the processor itself, memory systems and related controllers, and internal
buses. The processor state and registers, peripheral registers, and internal SRAM values
are maintained, and the logic levels of the pins remain static. Wake-up times are longer
compared to the Deep-sleep mode.
5.3.5.1 Power configuration in Power-down mode
Power consumption in power-down mode is determined by which analog wake-up
sources are enabled. Serial peripherals and pin interrupts configured to wake up the part
do not contribute significantly to the power consumption. All wake-up events (other than
reset) must be enabled in the STARTER registers and in the NVIC. In addition, any related
analog block (e.g. the RTC oscillator or the watchdog oscillator) must be explicitly enabled
through the power API function power_mode_configure() for wake-up. See
.
5.3.5.2 Programming Power-down mode
The following steps must be performed to enter Power-down mode:
1. Select wake-up sources and enable all related wake-up events in the STARTER
registers (
) and in the NVIC.
2. Select the IRC as the main clock and set the AHBCLKDIV register to 1. See
,
, and
3. Call the power API with the peripheral parameter set to enable the analog wake-up
sources:
pPWRD->power_mode_configure(POWER_DOWN, peripheral);
4. Execute the WFI instruction.
5.3.5.3 Wake-up from Power-down mode
The part can wake up from Power-down mode in the following ways:
•
Using a signal on one of the eight pin interrupts selected in
. Each pin interrupt must also be enabled in the STARTER0 register
(
) and in the NVIC.
•
Using an interrupt from a block such as the watchdog timer, RTC, or Micro-tick timer,
when enabled during the reduced power mode via the power API. Also enable the
wake-up sources in the STARTER registers (
and
) and the NVIC.
•
Using a reset from the RESET pin, or the BOD or WWDT (if enabled in the power
API).
•
Using a wake-up signal from any of the serial peripherals. Also enable the wake-up
sources in the STARTER registers (
and
) and the NVIC.
•
GPIO group interrupt signal. Interrupt must also be enabled in the STARTER1 register
(
) and in the NVIC.