ATMEGA640 datasheet(418/436 Pages) MICROCHIP

418 / 436 page

418

ATmega640/V-1280/V-1281/V-2560/V-2561/V [DATASHEET]

DS40002211A

37.10 ATmega2560 rev. C

• High current consumption in sleep mode

1. High current consumption in sleep mode

If a pending interrupt cannot wake the part up from the selected sleep mode, the current consumption will

increase during sleep when executing the SLEEP instruction directly after a SEI instruction.

Problem Fix/Workaround

Before entering sleep, interrupts not used to wake the part from the sleep mode should be disabled.

37.11 ATmega2560 rev. B

Not sampled.

37.12 ATmega2560 rev. A

• Non-Read-While-Write area of flash not functional

• Part does not work under 2.4 volts

• Incorrect ADC reading in differential mode

• Internal ADC reference has too low value

• IN/OUT instructions may be executed twice when Stack is in external RAM

• EEPROM read from application code does not work in Lock Bit Mode 3

Non-Read-While-Write area of flash not functional

The Non-Read-While-Write area of the flash is not working as expected. The problem is related to the speed of

the part when reading the flash of this area.

Problem Fix/Workaround

- Only use the first 248K of the flash.

- If boot functionality is needed, run the code in the Non-Read-While-Write area at maximum 1/4th of the max-

imum frequency of the device at any given voltage. This is done by writing the CLKPR register before entering

the boot section of the code.

2. Part does not work under 2.4 volts

The part does not execute code correctly below 2.4 volts.

Problem Fix/Workaround

Do not use the part at voltages below 2.4 volts.

3. Incorrect ADC reading in differential mode

The ADC has high noise in differential mode. It can give up to 7 LSB error.

Problem Fix/Workaround

Use only the 7 MSB of the result when using the ADC in differential mode.

4. Internal ADC reference has too low value

The internal ADC reference has a value lower than specified.

Problem Fix/Workaround

- Use AVCC or external reference.

- The actual value of the reference can be measured by applying a known voltage to the ADC when using the

internal reference. The result when doing later conversions can then be calibrated.

ATMEGA640 Datasheet(PDF) 418 Page - Microchip Technology