ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 42

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

10.9
10.10 Minimizing Power Consumption
10.10.1
10.10.2
10.10.3
42
Power Reduction Register
Atmel ATmega48PA/88PA/168PA [Preliminary]
Analog to Digital Converter
Analog Comparator
Brown-out Detector
The Power Reduction Register (PRR), see
provides a method to stop the clock to individual peripherals to reduce power consumption.
The current state of the peripheral is frozen and the I/O registers can not be read or written.
Resources used by the peripheral when stopping the clock will remain occupied, hence the
peripheral should in most cases be disabled before stopping the clock. Waking up a module,
which is done by clearing the bit in PRR, puts the module in the same state as before
shutdown.
Module shutdown can be used in Idle mode and Active mode to significantly reduce the overall
power consumption. In all other sleep modes, the clock is already stopped.
There are several possibilities to consider when trying to minimize the power consumption in
an AVR controlled system. In general, sleep modes should be used as much as possible, and
the sleep mode should be selected so that as few as possible of the device’s functions are
operating. All functions not needed should be disabled. In particular, the following modules
may need special consideration when trying to achieve the lowest possible power
consumption.
If enabled, the ADC will be enabled in all sleep modes. To save power, the ADC should be dis-
abled before entering any sleep mode. When the ADC is turned off and on again, the next
conversion will be an extended conversion. Refer to
for details on ADC operation.
When entering Idle mode, the Analog Comparator should be disabled if not used. When enter-
ing ADC Noise Reduction mode, the Analog Comparator should be disabled. In other sleep
modes, the Analog Comparator is automatically disabled. However, if the Analog Comparator
is set up to use the Internal Voltage Reference as input, the Analog Comparator should be dis-
abled in all sleep modes. Otherwise, the Internal Voltage Reference will be enabled,
independent of sleep mode. Refer to
configure the Analog Comparator.
If the Brown-out Detector is not needed by the application, this module should be turned off. If
the Brown-out Detector is enabled by the BODLEVEL Fuses, it will be enabled in all sleep
modes, and hence, always consume power. In the deeper sleep modes, this will contribute
significantly to the total current consumption. Refer to
details on how to configure the Brown-out Detector.
“Analog Comparator” on page 244
“PRR – Power Reduction Register” on page
“Analog-to-Digital Converter” on page 248
“Brown-out Detection” on page 50
for details on how to
9223B–AVR–09/11
45,
for