at49bv002an ATMEL Corporation, at49bv002an Datasheet - Page 6

• Manufacturer Part Number: at49bv002an
• Description: 2-megabit 256k X 8 Single 2.7-volt Battery-voltage Flash Memory
• Manufacturer: ATMEL Corporation

4.8
4.9
4.10
6
DATA Polling
Toggle Bit
Hardware Data Protection
AT49BV002A(N)(T)
The AT49BV002A(N)(T) features DATA polling to indicate the end of a program cycle. During a
program cycle an attempted read of the last byte loaded will result in the complement of the
loaded data on I/O7. Once the program cycle has been completed, true data is valid on all out-
puts and the next cycle may begin. DATA polling may begin at any time during the program
cycle.
In addition to DATA polling the AT49BV002A(N)(T) provides another method for determining the
end of a program or erase cycle. During a program or erase operation, successive attempts to
read data from the device will result in I/O6 toggling between one and zero. Once the program
cycle has completed, I/O6 will stop toggling and valid data will be read. Examining the toggle bit
may begin at any time during a program cycle.
Hardware features protect against inadvertent programs to the AT49BV002A(N)(T) in the
following ways: (a) V
(b) Program inhibit: holding any one of OE low, CE high or WE high inhibits program cycles.
(c) Noise filter: pulses of less than 15 ns (typical) on the WE or CE inputs will not initiate a
program cycle.
CC
sense: if V
CC
is below 1.8V (typical), the program function is inhibited.
3353G–FLASH–8/05