Bad blocks are blocks that contain one or more invalid bits whose reliability is not
guaranteed. Bad blocks may be present when the device is shipped, or may develop during
the lifetime of the device.
Devices with bad blocks have the same quality level and the same AC and DC
characteristics as devices where all the blocks are valid. A bad block does not affect the
performance of valid blocks because it is isolated from the bit line and common source line
by a select transistor.
Bad block management, block replacement and the error correction code software are
necessary to manage the error bits in NAND flash devices.
The application note covers all Numonyx NAND flash memories. Refer to the relative
datasheets for the full list of root part numbers and for further information on the devices.