
UM10800
All information provided in this document is subject to legal disclaimers.
© NXP Semiconductors N.V. 2016. All rights reserved.
User manual
Rev. 1.2 — 5 October 2016
70 of 487
NXP Semiconductors
UM10800
Chapter 6: LPC82x Reduced power modes and power management
Peripheral functions, if selected to be clocked in the SYSAHBCLKCTRL register, continue
operation during Sleep mode and may generate interrupts to cause the processor to
resume execution. Sleep mode eliminates 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.
6.7.4.1 Power configuration in Sleep mode
Power consumption in Sleep mode is configured by the same settings as in Active mode:
•
The clock remains running.
•
The system clock frequency remains the same as in Active mode, but the processor is
not clocked.
•
Analog and digital peripherals are selected as in Active mode.
6.7.4.2 Programming Sleep mode
The following steps must be performed to enter Sleep mode:
1. The PM bits in the PCON register must be set to the default value 0x0.
2. The SLEEPDEEP bit in the ARM Cortex-M0+ SCR register must be set to zero
(
).
3. Use the ARM Cortex-M0+ Wait-For-Interrupt (WFI) instruction.
6.7.4.3 Wake-up from Sleep mode
Sleep mode is exited automatically when an interrupt enabled by the NVIC arrives at the
processor or a reset occurs. After wake-up due to an interrupt, the microcontroller returns
to its original power configuration defined by the contents of the PDRUNCFG and the
SYSAHBCLKDIV registers. If a reset occurs, the microcontroller enters the default
configuration in Active mode.
6.7.5 Deep-sleep mode
In Deep-sleep mode, the system clock to the processor is disabled as in Sleep mode. All
analog blocks are powered down, except for the BOD circuit and the watchdog oscillator,
which can be selected or deselected during Deep-sleep mode in the PDSLEEPCFG
register. The main clock, and therefore all peripheral clocks, are disabled except for the
clock to the watchdog timer if the watchdog oscillator is selected. The IRC is running, but
its output is disabled. The flash is in standby mode.
Deep-sleep mode eliminates 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.
6.7.5.1 Power configuration in Deep-sleep mode
Power consumption in Deep-sleep mode is determined by the Deep-sleep power
configuration setting in the PDSLEEPCFG (
) register:
•
The watchdog oscillator can be left running in Deep-sleep mode if required for the
WWDT.