ACSR Analog Comparator Control and Status Register
To disable Analog Comparator
ACSR = 0x80;
or
ACSR &= ~_BV(ACIE);
ACSR |= _BV(ACD);
ACD: Analog Comparator Disable
When this bit is written logic one, the power to the Analog Comparator is
switched off. This bit can be set at any time to turn off the Analog
Comparator. This will reduce power consumption in Active and Idle mode.
When changing the ACD bit, the Analog Comparator Interrupt must be disabled
by clearing the ACIE bit in ACSR. Otherwise an interrupt can occur when
the bit is changed.
DIDR1 Digital Input Disable Register 1
AIN1D
AIN0D
When this bit is written logic one, the digital input buffer on the AIN1/0 pin is disabled. The corresponding PIN Register bit will always read as zero when this bit is set. When an analog signal is applied to the AIN1/0 pin and the digital input from this pin is not needed, this bit should be written logic one to reduce power consumption in the digital input buffer.