ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 40

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

10.2
10.3
10.4
40
Idle Mode
ADC Noise Reduction Mode
BOD Disable
Atmel ATmega48PA/88PA/168PA [Preliminary]
()
When the Brown-out Detector (BOD) is enabled by BODLEVEL fuses - see
page 297
sleep period. To save power, it is possible to disable the BOD by software for some of the
sleep modes, see
the same level as when BOD is globally disabled by fuses. If BOD is disabled in software, the
BOD function is turned off immediately after entering the sleep mode. Upon wake-up from
sleep, BOD is automatically enabled again. This ensures safe operation in case the V
has dropped during the sleep period.
When the BOD has been disabled, the wake-up time from sleep mode will be approximately
60 µs to ensure that the BOD is working correctly before the MCU continues executing code.
BOD disable is controlled by bit 6, BODS (BOD Sleep) in the control register MCUCR, see
“MCUCR – MCU Control Register” on page
evant sleep modes, while a zero in this bit keeps BOD active. Default setting keeps BOD
active, i.e. BODS set to zero.
Writing to the BODS bit is controlled by a timed sequence and an enable bit, see
MCU Control Register” on page
Note:
When the SM2...0 bits are written to 000, the SLEEP instruction makes the MCU enter Idle
mode, stopping the CPU but allowing the SPI, USART, Analog Comparator, ADC, 2-wire
Serial Interface, Timer/Counters, Watchdog, and the interrupt system to continue operating.
This sleep mode basically halts clk
Idle mode enables the MCU to wake up from external triggered interrupts as well as internal
ones like the Timer Overflow and USART Transmit Complete interrupts. If wake-up from the
Analog Comparator interrupt is not required, the Analog Comparator can be powered down by
setting the ACD bit in the Analog Comparator Control and Status Register – ACSR. This will
reduce power consumption in Idle mode. If the ADC is enabled, a conversion starts automati-
cally when this mode is entered.
When the SM2...0 bits are written to 001, the SLEEP instruction makes the MCU enter ADC
Noise Reduction mode, stopping the CPU but allowing the ADC, the external interrupts, the
2-wire Serial Interface address watch, Timer/Counter2
ating (if enabled). This sleep mode basically halts clk
the other clocks to run.
This improves the noise environment for the ADC, enabling higher resolution measurements.
If the ADC is enabled, a conversion starts automatically when this mode is entered. Apart from
the ADC Conversion Complete interrupt, only an External Reset, a Watchdog System Reset, a
Watchdog Interrupt, a Brown-out Reset, a 2-wire Serial Interface address match, a
Timer/Counter2 interrupt, an SPM/EEPROM ready interrupt, an external level interrupt on
INT0 or INT1 or a pin change interrupt can wake up the MCU from ADC Noise Reduction
mode.
Note:
1. BOD disable only available in picoPower devices ATmega48PA/88PA/168PA
1. Timer/Counter2 will only keep running in asynchronous mode, see
and onwards, the BOD is actively monitoring the power supply voltage during a
with PWM and Asynchronous Operation” on page 143
Table 10-1 on page
45.
CPU
and clk
39. The sleep mode power consumption will then be at
45. Writing this bit to one turns off the BOD in rel-
FLASH
, while allowing the other clocks to run.
(1)
I/O
, and the Watchdog to continue oper-
, clk
for details.
CPU
, and clk
“8-bit Timer/Counter2
FLASH
, while allowing
Table 28-7 on
9223B–AVR–09/11
“MCUCR –
CC
level