ATmega16HVB datasheet(35/273 Pages) ATMEL

35 / 273 page

8042A–AVR–07/09

ATmega16HVB/32HVB

10. Power Management and Sleep Modes

Sleep modes enable the application to shut down unused modules in the MCU, thereby saving

power. The AVR provides various sleep modes allowing the user to tailor the power consump-

tion to the application’s requirements.

10.1

Sleep Modes

Figure 9-1 on page 25 presents the different clock systems in the ATmega16HVB/32HVB, and

their distribution. The figure is helpful in selecting an appropriate sleep mode. The different sleep

modes and their wake up sources is summarized in Table 10-1, and Figure 10-1 on page 36

shows a sleep mode state diagram.

Notes:

1. Discharge FET must be switched off for Charge Detect to be active.

2. When waking from Power-off the Charger Detect will generate a Power-on Reset (POR). From other sleep modes a charger

detect interrupt will wake-up chip.

To enter any of the sleep modes, the SE bit in SMCR, see ”SMCR – Sleep Mode Control Regis-

ter” on page 39, must be written to logic one and a SLEEP instruction must be executed. The

SM2..0 bits in the SMCR Register select which sleep mode will be activated by the SLEEP

instruction. See Table 10-3 on page 40 for a summary.

If an enabled interrupt occurs while the MCU is in a sleep mode, the MCU wakes up. The MCU

is then halted for four cycles in addition to the start-up time, executes the interrupt routine, and

resumes execution from the instruction following SLEEP. The contents of the register file and

SRAM are unaltered when the device wakes up from any sleep mode except Power-off. If a

reset occurs during sleep mode, the MCU wakes up and executes from the Reset Vector.

Table 10-1.

Wake-up Sources for Sleep Modes

Mode

Wake-up sources

Idle

XXX

ADC Noise Reduction

XXX

Power-save

XXX

Power-off

ATmega16HVB Datasheet(PDF) 35 Page - ATMEL Corporation