ata6616 ATMEL Corporation, ata6616 Datasheet - Page 247

• Manufacturer Part Number: ata6616
• Description: Microcontroller With Lin Transceiver, 5v Regulator And Watchdog
• Manufacturer: ATMEL Corporation

4.21.2.5
4.21.2.6
9132A–AUTO–10/08
DRAFT
Preventing Flash Corruption
Programming Time for Flash when Using SPM
During periods of low Vcc, the Flash program can be corrupted because the supply voltage is
too low for the CPU and the Flash to operate properly. These issues are the same as for board
level systems using the Flash, and the same design solutions should be applied.
A Flash program corruption can be caused by two situations when the voltage is too low.
Flash corruption can easily be avoided by following these design recommendations (one is
sufficient):
The calibrated RC Oscillator is used to time Flash accesses.
gramming time for Flash accesses from the CPU.
Table 4-65.
Flash write (Page Erase, Page Write, and
• First, a regular write sequence to the Flash requires a minimum voltage to operate correctly.
• Secondly, the CPU itself can execute instructions incorrectly, if the supply voltage for
1. Keep the AVR RESET active (low) during periods of insufficient power supply voltage.
2. Keep the AVR core in Power-down sleep mode during periods of low Vcc. This will pre-
executing instructions is too low.
This can be done by enabling the internal Brown-out Detector (BOD) if the operating
voltage matches the detection level. If not, an external low Vcc reset protection circuit
can be used. If a reset occurs while a write operation is in progress, the write operation
will be completed provided that the power supply voltage is sufficient.
vent the CPU from attempting to decode and execute instructions, effectively protecting
the SPMCSR Register and thus the Flash from unintentional writes.
write Lock bits by SPM)
SPM Programming Time
Symbol
ATA6616/ATA6617 [Preliminary]
Min Programming Time
3.7 ms
Table 4-65
Max Programming Time
shows the typical pro-
4.5 ms
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