AM49PDL129AH datasheet(39/82 Pages) SPANSION

39 / 82 page

December 18, 2003

Am49PDL127AH/Am49PDL129AH

ADV ANCE

I N FO RMAT I O N

Note that the WP#/ACC pin must not be left floating or

unconnected; inconsistent behavior of the device may

result.

Persistent Protection Bit Lock

The Persistent Protection Bit (PPB) Lock is a volatile

bit that reflects the state of the Password Mode Lock-

ing Bit after power-up reset. If the Password Mode

Lock Bit is also set after a hardware reset (RESET#

asserted) or a power-up reset, the ONLY means for

clearing the PPB Lock Bit in Password Protection

Mode is to issue the Password Unlock command. Suc-

cessful execution of the Password Unlock command

clears the PPB Lock Bit, allowing for sector PPBs

modifications. Asserting RESET#, taking the device

through a power-on reset, or issuing the PPB Lock Bit

Set command sets the PPB Lock Bit to a “1” when the

Password Mode Lock Bit is not set.

If the Password Mode Locking Bit is not set, including

Persistent Protection Mode, the PPB Lock Bit is

cleared after power-up or hardware reset. The PPB

Lock Bit is set by issuing the PPB Lock Bit Set com-

mand. Once set the only means for clearing the PPB

Lock Bit is by issuing a hardware or power-up reset.

The Password Unlock command is ignored in Persis-

tent Protection Mode.

High Voltage Sector Protection

Sector protection and unprotection may also be imple-

mented using programming equipment. The proce-

dure requires high voltage (VID) to be placed on the

RESET# pin. Refer to Figure 1 for details on this pro-

cedure. Note that for sector unprotect, all unprotected

sectors must first be protected prior to the first sector

write cycle.

AM49PDL129AH Datasheet(PDF) 39 Page - SPANSION