atmega3250v-8auatmega325v-8ai ATMEL Corporation, atmega3250v-8auatmega325v-8ai Datasheet - Page 37

• Manufacturer Part Number: atmega3250v-8auatmega325v-8ai
• Description: Atmega3250 8-bit Microcontroller With In-system Programmable Flash
• Manufacturer: ATMEL Corporation

10.8.5
10.8.6
10.8.7
2570L–AVR–08/07
Watchdog Timer
Port Pins
JTAG Interface and On-chip Debug System
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
age Reference” on page 43
If the Watchdog Timer is not needed in the application, the 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 consump-
tion. Refer to
When entering a sleep mode, all port pins should be configured to use minimum power. The
most important is then to ensure that no pins drive resistive loads. In sleep modes where both
the I/O clock (clk
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
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
For analog input pins, the digital input buffer should be disabled at all times. An analog signal
level close to V
input buffers can be disabled by writing to the Digital Input Disable Registers (DIDR1 and
DIDR0). Refer to
Input Disable Register 0” on page 216
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:
•
•
•
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 con-
tains 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.
Disable OCDEN Fuse.
Disable JTAGEN Fuse.
Write one to the JTD bit in MCUCSR.
“Watchdog Timer” on page 44
CC
I/O
“DIDR1 – Digital Input Disable Register 1” on page 199
/2 on an input pin can cause significant current even in active mode. Digital
) and the ADC clock (clk
for details on the start-up time.
“Digital Input Enable and Sleep Modes” on page 64
CC
/2, the input buffer will use excessive power.
for details.
ADC
for details on how to configure the Watchdog Timer.
ATmega325/3250/645/6450
) are stopped, the input buffers of the device will
and
“DIDR0 – Digital
“Internal Volt-
for details on
37