Intel PXA27X manual Intel PXA27x Processor Low Power Operating Modes, Application Note

Intel® PXA27x Processor Family Power Requirements

3.0Intel® PXA27x Processor Low Power Operating Modes

The PXA27x processor provides several low-power operating modes that temporarily suspend or power down the core or peripherals to reduce power consumption. The external power supplies are disabled in some modes. Transitions between certain domains require a sequence of events and handshakes between the PXA27x processor and the external power management integrated circuit (PMIC) that are detailed in this section.

The PXA27x processor supports six operating modes, shown in Table 7.

Table 7. Intel® PXA27x Processor Operating Modes

Operating Modes	Description
Normal mode	All external power supplies are enabled and all internal domains are powered. The CPU
(Run/Turbo mode)	core and peripherals are fully functional.
Idle mode	The clocks to the CPU are disabled but context is retained. The peripherals continue
	normal operation. All power supplies are enabled. An interrupt assertion causes the
	transition back to normal mode.
Deep Idle mode	The core frequency is at 13 MHz (CCCR[CDPIS] is set) and the processor is in idle
	mode.
Standby mode	The clocks to the CPU are disabled and the CPU is placed in a low leakage state but
	context is retained. All external power supplies are enabled. Each internal SRAM bank
	can be independently placed in a low-power mode where the state is retained but no
	activity is allowed under program control. The PLLs are disabled and peripheral
	operation is suspended. An interrupt assertion causes the transition back to normal
	mode.
Sleep mode	All internal power domains except VCC_RTC and VCC_OSC are optionally powered
	down. All clock sources except the real-time clock (RTC) and power manager are
	disabled, and all external low-voltage power supplies (VCC_CORE, VCC_PLL, and
	VCC_SRAM) controlled by PWR_EN are disabled. Recovery is initiated by external
	wake-up events or select internal wake-up events. A system reboot is required because
	the program counter is invalid.
Deep sleep mode	All internal power domains except VCC_RTC and VCC_OSC are powered down. All
	clock sources except the real-time clock (RTC) and power manager are disabled, and the
	external low-voltage supplies (VCC_CORE, VCC_PLL, and VCC_SRAM) controlled by
	PWR_EN are disabled. The high-voltage power supplies (VCC_IO, VCC_MEM,
	VCC_LCD, VCC_BB and VCC_USIM) controlled by SYS_EN are disabled. The active
	internal power domains are powered from one of three internal regulators driven from the
	backup battery signal, VCC_BATT. Recovery is initiated by external or select internal
	wake-up events and requires a system reboot, because the program counter is invalid.

NOTE: Refer to the Intel® PXA27x Processor Family Developers Manual, “Clocks and Power” section for more information on low power modes

The state diagram in Figure 3 shows the transitions between operating modes and the events and conditions that cause or enable transitions.

Application Note 17