ATMEGA128

Power Consumption Discussion
 

General
 

• Based on field test of Rev.0 AM128 Board
• Chip version ATMEGA128-16AC
• Tested at 5 Volt supply from regulator
• The Power LED (green) draws 4.5 mA.  This value is included in the figures below.
• The Run LED (red) was off for the power consumption testing.
• The MAX221 RS-232 interface is powered (5 to 10 mA per data sheet)
• TCNT0 enabled with 32KHz crystal
• Brown-out detection enabled.
• ADC disabled.

                                                  All values in mA

                                               Normal  Idle  Power Down     Standby

14.7 MHz Crystal     Board        45        33          12                      12
                                uC             33        21           0                        0

7.3 MHz Crystal       Board        34        27          12                      12
                                uC             22        15           0                        0

Discussion
 

• The AVR ISP adds 16 ma to the load when attached.
• The 12 mA in Power Down / Standby modes is due almost entirely to the Power LED and MAX221 RS-232 interface.
• Increasing the clock frequency from 7.3 to 14.7 MHz does not have as dramatic an impact as the discussion in the Atmel ATMEGA128 Documentation would lead one to believe.

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