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AT29LV512-12JC

512K 64K x 8 3-volt Only CMOS Flash Memory

Atmel Corporation 

Block Diagram

To allow for simple in-system reprogrammability, the AT29LV512 does not require high

input voltages for programming. Three-volt-only commands determine the operation of

the device. Reading data out of the device is similar to reading from an EPROM. Repro-

gramming the AT29LV512 is performed on a sector basis; 128 bytes of data are loaded

into the device and then simultaneously programmed.

During a reprogram cycle, the address locations and 128 bytes of data are captured at

microprocessor speed and internally latched, freeing the address and data bus for other

operations. Following the initiation of a program cycle, the device will automatically

erase the sector and then program the latched data using an internal control timer. The

end of a program cycle can be detected by DATA polling of I/O7. Once the end of a pro-

gram cycle has been detected, a new access for a read or program can begin.

Device Operation

READ: The AT29LV512 is accessed like an EPROM. When CE and OE are low and

WE is high, the data stored at the memory location determined by the address pins

is asserted on the outputs. The outputs are put in the high impedance state whenever

CE or OE is high. This dual-line control gives designers flexibility in preventing bus

contention.

SOFTWARE DATA PROTECTION PROGRAMMING: The AT29LV512 has 512 individ-

ual sectors, each 128 bytes. Using the software data protection feature, byte loads are

used to enter the 128 bytes of a sector to be programmed. The AT29LV512 can only be

programmed or reprogrammed using the software data protection feature. The device is

programmed on a sector basis. If a byte of data within the sector is to be changed, data

for the entire 128-byte sector must be loaded into the device. The AT29LV512 automat-

ically does a sector erase prior to loading the data into the sector. An erase command is

not required.

Software data protection protects the device from inadvertent programming. A series of

three program commands to specific addresses with specific data must be presented to

the device before programming may occur. After writing the three-byte command

sequence (and after tWC), the entire device is protected. The same three program com-

mands must begin each program operation. All software program commands must obey

the sector program timing specifications. Power transitions will not reset the software

data protection feature; however, the software feature will guard against inadvertent

program cycles during power transitions.

2 AT29LV512

0177M–05/02

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