AT90USB64/128
35. Errata
The revision letter in this section refers to the revision of the AT90USB64/128 device.
35.1 Rev A
• VBUS residual level
• Spike on TWI pins when TWI is enabled
• High current consumption in sleep mode
• Async timer interrupt wake up from sleep generate multiple interrupts
4.
VBUS residual level
In USB device and host mode, once a 5V level has been detected to the VBUS pad, a resid-
ual level (about 3V) can be measured on the VBUS pin.
Problem fix/workaround
None.
3. Spike on TWI pins when TWI is enabled
100 ns negative spike occurs on SDA and SCL pins when TWI is enabled.
Problem Fix/workaround
No known workaround, enable AT90USB64/128 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/workaround
Before entering sleep, interrupts not used to wake up the part from the sleep mode should
be disabled.
1. Asynchonous timer interrupt wake up from sleep generates multiple interrupts
If the cpu core is in sleep and wakeups from an asynchronous timer interrupt and then go
back in sleep again it may wake up multiple times.
Problem Fix/workaround
A software workaround is to wait with performing the sleep instruction until
TCNT2>OCR2+1.
425
7593A–AVR–02/06
ATMEL [ ATMEL ]
