W39V040FA

Publication Release Date: December 19, 2002

- 7 -

Revision A2

Read Lock

Any attempt to read the data of read locked block will result in “00.” The default state of any block is

unlocked upon power up. User can clear or set the write lock bit anytime as long as the lock down bit

is not set.

Write Lock

This is the default state of blocks upon power up. Before any program or erase to the specified block,

user should clear the write lock bit first. User can clear or set the write lock bit anytime as long as the

lock down bit is not set. The write lock function is in conjunction with the hardware protect pins, #WP &

TBL. When hardware protect pins are enabled, it will override the register block locking functions and

write lock the blocks no matter how the status of the register bits. Reading the register bit will not

reflect the status of the #WP or #TBL pins.

Lock Down

The default state of lock down bit for any block is unlocked. This bit can be set only once; any further

attempt to set or clear is ignored. Only the reset from #RESET or #INIT can clear the lock down bit.

Once the lock down bit is set for a block, then the write lock bit & read lock bit of that block will not be

set or cleared, and keep its current state.

Product Identification Registers

In the FWH interface mode, a read from FFBC, 0000(hex) can output the manufacturer code,

DA(hex). A read from FFBC, 0001(hex) can output the device code 34(hex).

There is an alternative software method (six commands bytes) to read out the Product Identification in

both the Programmer interface mode and the FWH interface mode. Thus, the programming equipment

can automatically matches the device with its proper erase and programming algorithms.

In the software access mode, a six-byte (or JEDEC 3-byte) command sequence can be used to

access the product ID for programmer interface mode. A read from address 0000(hex) outputs the

manufacturer code, DA(hex). A read from address 0001(hex) outputs the device code, 34(hex).” The

product ID operation can be terminated by a three-byte command sequence or an alternate one-byte

command sequence (see Command Definition table for detail).

Table of Operating Mode

Operating Mode Selection - Programmer Mode

PINS

MODE

#OE

#WE

#RESET

ADDRESS

DQ.

Read

AIN

Dout

Write

AIN

Din

Standby

X

X

X

High Z

X

X

High Z/DOUT

Write Inhibit

X

X

High Z/DOUT

Output Disable

X

X

High Z