HY29LV400 Hynix Semiconductor, HY29LV400 Datasheet - Page 9

• Manufacturer Part Number: HY29LV400
• Description: 4 Mbit (512K x 8/256K x 16) Low Voltage Flash Memory
• Manufacturer: Hynix Semiconductor

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Sector Protect Operation
The hardware sector protection feature disables
both program and erase operations in any sector
or combination of sectors. This function can be
implemented either in-system or by using program-
ming equipment.
The Sector Protect procedure requires V
RESET# pin and uses standard microprocessor
bus cycle timing to implement sector protection.
The flow chart in Figure 1 illustrates the algorithm.
The HY29LV400 is shipped with all sectors un-
protected. It is possible to determine whether a
sector is protected or unprotected. See the Elec-
tronic ID Mode section for details.
Sector Unprotect Operation
The hardware sector unprotection feature re-en-
ables both program and erase operations in pre-
viously protected sectors. This function can be
implemented either in-system or by using program-
ming equipment. Note that to unprotect any sec-
tor, all unprotected sectors must first be protected
prior to the first sector unprotect write cycle. Also,
the unprotect procedure will cause all sectors to
become unprotected, thus, sectors that require
Rev. 1.0/Nov. 01
A[17:12] = Sector to Protect
A[6] = 0, A[1] = 1, A[0] = 0
Write 0x60 to Address
Write 0x60 to device
R E S E T # = V
TRYCNT = 1
Set Address:
Wait 1 us
S T A R T
ID
Figure 1. Sector Protect Algorithm
Write 0x40 to Address
Read from Address
Protect Another
Data = 0x01?
Wait 150 us
Sector?
ID
on the
Y E S
Y E S
N O
N O
protection must be protected again after the un-
protect procedure is run.
The Sector Unprotect procedure requires V
the RESET# pin and uses standard microproces-
sor bus cycle timing to implement sector unpro-
tection. The flow chart in Figure 2 illustrates the
algorithm.
Temporary Sector Unprotect Operation
This feature allows temporary unprotection of pre-
viously protected sectors to allow changing the
data in-system. Sector Unprotect mode is activated
by setting the RESET# pin to V
mode, formerly protected sectors can be pro-
grammed or erased by invoking the appropriate
commands (see Device Commands section).
Once V
ously protected sectors are protected again. Fig-
ure 3 illustrates the algorithm.
Electronic ID Operation (High Voltage Method)
The Electronic ID mode provides manufacturer and
device identification and sector protection verifi-
cation through codes output on DQ[15:0]. This
mode is intended primarily for programming equip-
ment to automatically match a device to be pro-
Increment TRYCNT
T R Y C N T = 2 5 ?
ID
is removed from RESET#, all the previ-
N O
Y E S
W r i t e R e s e t C o m m a n d
SECTOR PROTECT
DEVICE FAILURE
ID
R E S E T # = V
C O M P L E T E
. While in this
HY29LV400
IH
ID
on
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