Errata for at90s/ls4433 rev. rev. c/d/e/f – Rainbow Electronics AT90LS4433 User Manual
Page 119
119
AT90S/LS4433
1042G–AVR–09/02
Errata for
AT90S/LS4433 Rev.
Rev. C/D/E/F
•
Fuses and Programming Mode
•
Incorrect Channel Change in Free Running Mode
•
Bandgap Reference Stabilizing Time
•
Brown-out Detection Level
•
Serial Programming at Voltages below 2.9V
•
UART Loses Synchronization if RXD Line is Low when UART Receive is Disabled
6.
Fuses and Programming Mode
After programming the Fuses in Serial Programming mode, it is not possible to pro-
gram the Flash or EEPROM. If leaving Programming mode, it is not possible to re-
enter Programming mode.
Problem Fix/Workaround
Power the part down and backup again after programming the Fuses or leaving Pro-
gramming mode.
5.
Incorrect Channel Change in Free Running Mode
If the ADC operates in Free Running mode and channels are changed by writing to
ADMUX, shortly after the ADC Interrupt Flag (ADIF in ADCSR) is set, the new set-
ting in ADMUX may affect the ongoing conversion.
Problem Fix/Workaround
Use Single Conversion mode when scanning channels, or avoid changing ADMUX
util at least 0.5 ADC clock cycles after ADIF goes high.
4.
Bandgap Reference Stabilizing Time
The time for the internal voltage reference for the Analog Comparator to stabilize is
longer than specified. The stabilizing period starts after the bandgap reference has
been selected, and can go on for as much as 10 seconds.
Problem Fix/Workaround
The Bandgap reference will be stable immediately if the internal Brown-out Detector
is enabled.
3.
Brown-out Detection Level
The Brown-out Detection level can increase when there is heavy I/O-activity on the
device. The increase can be significant when some of the I/O pins are driving heavy
loads.
Problem Fix/Workaround
Select a V
CC
well above the Brown-out Detection level.
Avoid loading I/O ports with high capacitive or resistive loads.
2.
Serial Programming at Voltages below 2.9V
At voltages below 2.9V, serial programming might fail.
Problem Fix/Workaround
Keep V
CC
at 2.9V or higher during In-System Programming.