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ATmega64A [DATASHEET]
8160D–AVR–02/2013
10.7.3
Brown-out Detector
If the Brown-out Detector is not needed in the application, this module should be turned off. If the Brown-out Detec-
tor 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 Detec-10.7.4
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
10.7.5
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
how to configure the Watchdog Timer.
10.7.6
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 con-
sumed by the input logic when not needed. In some cases, the input logic is needed for detecting wake-up
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.
10.7.7
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 that avoids this problem. Writing the JTD bit
in the MCUCSR register to one or leaving the JTAG fuse unprogrammed disables the JTAG interface.