HY29F800 Hynix Semiconductor, HY29F800 Datasheet - Page 9

• Manufacturer Part Number: HY29F800
• Description: 8 Megabit (1Mx8/512Kx16), 5 Volt-only, Flash Memory
• Manufacturer: Hynix Semiconductor

The flow chart in Figure 1 illustrates the proce-
dure for protecting sectors, and timing specifica-
tions and waveforms are shown in the specifica-
tions section of this document. Verification of pro-
tection is accomplished as described in the Elec-
tronic ID Mode section and shown in the flow chart.
The procedure for sector unprotection is illustrated
in the flow chart in Figure 2, and timing specifica-
tions and waveforms are given at the end of this
document. Note that to unprotect any sector, all
unprotected sectors must first be protected prior
to the first unprotect write cycle.
Sectors can also be temporarily unprotected as
described in the next section.
Temporary Sector Unprotect Operation
This feature allows temporary unprotection of pre-
viously protected sectors to allow changing the
data in-system. Temporary Sector Unprotect
mode is activated by setting the RESET# pin to
Rev. 4.2/May 01
NOTE: All sectors must be
Set: A9 = CE# = OE# = V
previously protected.
Set: RESET# = V
Set: TRYCNT = 1
OE# = CE# = V
Set: NSEC = 0
APPLY V
W E # = V
W E # = V
Wait t
A9 = V
START
Set:
W P P 2
ID
CC
IL
IH
IL
IH
ID
Figure 2. Sector Unprotect Procedure
Set Sector Group Address:
A[18:12] = Sector NSEC
NSEC = NSEC + 1
A0 = A6 = V
Data = 0x00?
NSEC = 18?
Read Data
A1 = V
Y E S
N O
IH
IL
N O
Y E S
V
tors can be programmed or erased by invoking
the appropriate commands (see Device Com-
mands section). Once V
SET#, all the previously protected sectors are pro-
tected again. Figure 3 illustrates the algorithm.
Electronic ID Mode Operation
The Electronic ID mode provides manufacturer and
device identification and sector protection verifi-
cation through identifier codes output on DQ[7:0]
or DQ[15:0]. This mode is intended primarily for
programming equipment to automatically match
a device to be programmed with its correspond-
ing programming algorithm. The Electronic ID in-
formation can also be obtained by the host through
a command sequence, as described in the De-
vice Commands section.
Operation in the Electronic ID mode requires V
on address pin A[9], with additional requirements
ID
. While in this mode, formerly protected sec-
SECTOR UNPROTECT
Remove V
Increment TRYCNT
TRYCNT = 1000?
C O M P L E T E
ID
N O
from A9
Y E S
ID
is removed from RE-
DEVICE FAILURE
HY29F800
ID
9