20

7766DS–AVR–01/09

ATmega16U4/ATmega32U4

8.

Errata

The revision letter in this section refers to the revision of the ATmega16U4/ATmega32U4

device.

8.1

ATmega16U4/ATmega32U4 Rev A

1.

Spike on TWI pins when TWI is enabled

100 ns negative spike occurs on SDA and SCL pins when TWI is enabled.

Problem Fix/work around

No known work around, enable ATmega16U4/ATmega32U4 TWI first versus the others

nodes of the TWI network.

2.

High current consumption in sleep mode

If a pending interrupt cannot wake the part up from the selected mode, the current consump-

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

instruction.

Problem Fix/work around

Before entering sleep, interrupts not used to wake up the part from the sleep mode should

be disabled.

3.

Extra power comsumption

The typical power comsumption is increased by about 30µA in power-down mode.

Problem Fix/work around

None.

4.

Internal RC oscillator start up issue.

When the part is configured to start on internal RC, the oscillator may not start properly after

power-on.

Problem Fix/work around

Do not configure the part to start with the internal oscillator (default part configuration is to

start with the external crystal oscillator).

5.

Internal RC oscillator calibration issue.

The default internal RC oscillator frequency may be lower that 8MHz.

Problem Fix/work around

Parts are configured so that the internal RC oscillator frequency is as close as possible to

the 8MHz default target frequency.

9.

Incorrect CPU behavior for VBUSTI interrupt routine

The CPU core may incorrectly execute the interrupt vector related to the VBUSTI interrupt

flag.

Problem fix/workaround

Do not enable this interrupt, firmware must process this USB event by polling VBUSTI.