HY29F400 Hynix Semiconductor, HY29F400 Datasheet - Page 8

• Manufacturer Part Number: HY29F400
• Description: 4 Megabit (512Kx8/256Kx16) 5 Volt-only Flash Memory
• Manufacturer: Hynix Semiconductor

HY29F400
If RESET# is asserted during a program or erase
operation, the RY/BY# pin remains Low (busy) until
the internal reset operation is complete, which re-
quires a time of t
rithms). The system can thus monitor RY/BY# to
determine when the reset operation completes,
and can perform a read or write operation t
RY/BY# goes High. If RESET# is asserted when
a program or erase operation is not executing (RY/
BY# pin is High), the reset operation is completed
within a time of t
form a read or write operation t
SET# pin returns High .
The RESET# pin may be tied to the system reset
signal. Thus, a system reset would also reset the
device, enabling the system to read the boot-up
firmware from the Flash memory.
Sector Protect/Unprotect Operations
Hardware sector protection can be invoked to dis-
able program and erase operations in any single
sector or combination of sectors. This function is
typically used to protect data in the device from
unauthorized or accidental attempts to program
8
A[17:12] = Sector to Protect
Set A[9] = OE# = V
Set TRYCNT = 1
R E S E T # = V
Set Address:
A P P L Y V
W E # = V
CE# = V
START
CC
IL
IL
IH
RP
ID
. In this case, the host can per-
READY
(during Automatic Algo-
Figure 1. Sector Protect Procedure
RH
A[17:12] = Sector to Protect
A[6] = A[0] = V
after the RE-
OE# = CE# = V
Protect Another
Data = 0x01?
Read Data
W E # = V
Wait t
A[9] = V
Sector?
RB
W P P 1
Y E S
Y E S
IL
, A[1] = V
after
ID
IH
IL
IH
N O
N O
or erase the device while it is in the system (e.g.,
by a virus) and is implemented using program-
ming equipment. Sector unprotection re-enables
the program and erase operations in previously
protected sectors.
Table 1 identifies the eleven sectors and the ad-
dress range that each covers for both versions of
the device. The device is shipped with all sectors
unprotected.
The sector protect/unprotect operations require a
high voltage (V
and/or OE# control pins, as detailed in Table 3.
When implementing these operations, note that
V
V
ing V
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.
CC
ID
, and that V
must be applied to the device before applying
CC
Increment TRYCNT
DEVICE FAILURE
from the device.
T R Y C N T = 2 5 ?
ID
N O
Y E S
ID
should be removed before remov-
) on address pin A[9] and the CE#
R e m o v e V
SECTOR PROTECT
C O M P L E T E
ID
Rev. 5.2/May 01
from A[9]