Datasheet

13.8.3. Brown-out Detector
If the Brown-out Detector is not needed in the application, this module should be turned off. If the Brown-
out Detector is enabled by the BODEN Fuse, 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 Brown-out Detection for details on how to configure the Brown-out Detector.
Related Links
Brown-out Detection on page 56
13.8.4. Internal Voltage Reference
The Internal Voltage Reference will be enabled when needed by the Brown-out Detector, the Analog
Comparator or the ADC. If these modules are disabled as described in the sections above, the internal
voltage reference will be disabled and it will not be consuming power. When turned on again, the user
must allow the reference to start up before the output is used. If the reference is kept on in sleep mode,
the output can be used immediately. Refer to Internal Voltage Reference for details on the start-up time.
Related Links
Internal Voltage Reference on page 57
13.8.5. Watchdog Timer
If the Watchdog Timer is not needed in the application, this module should be turned off. If the Watchdog
Timer is enabled, 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 Watchdog Timer
for details on how to configure the Watchdog Timer.
Related Links
Watchdog Timer on page 57
13.8.6. Port Pins
When entering a sleep mode, all port pins should be configured to use minimum power. The most
important thing is then to ensure that no pins drive resistive loads. In sleep modes where the both the I/O
clock (clk
I/O
) and the ADC clock (clk
ADC
) are stopped, the input buffers of the device will be disabled. This
ensures that no power is consumed by the input logic when not needed. In some cases, the input logic is
needed for detecting wake-up conditions, and it will then be enabled. Refer to the section Digital Input
Enable and Sleep Modes for details on which pins are enabled. If the input buffer is enabled and the input
signal is left floating or have an analog signal level close to V
CC
/2, the input buffer will use excessive
power.
Related Links
Digital Input Enable and Sleep Modes on page 78
13.8.7. JTAG Interface and On-chip Debug System
If the On-chip debug system is enabled by the OCDEN Fuse and the chip enter Power down or Power
save sleep mode, the main clock source remains enabled. In these sleep modes, this will contribute
significantly to the total current consumption. There are three alternative ways to avoid this:
• Disable OCDEN Fuse.
• Disable JTAGEN Fuse.
• Write one to the JTD bit in MCUCSR.
The TDO pin is left floating when the JTAG interface is enabled while the JTAG TAP controller is not
shifting data. If the hardware connected to the TDO pin does not pull up the logic level, power
consumption will increase. Note that the TDI pin for the next device in the scan chain contains a pull-up
Atmel ATmega32A [DATASHEET]
Atmel-8155I-ATmega32A_Datasheet_Complete-08/2016
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