FLASH
AS8F128K32
Austin Semiconductor, Inc.
Low VCC Write Inhibit
Sector Protection/Unprotection
The hardware sector protection feature disables both
program and erase operations in any sector. The hardware
sector unprotection feature re-enables both program and erase
operations in previously protected sectors.
When VCC is less than VLKO, the device does not accept
any write cycles. This protects data during VCC power-up and
power-down. The command register and all internal program/
erase circuits are disabled, and the device resets. Subsequent
writes are ignored until VCC is greater than VLKO. The system
must provide the proper signals to the control pins to prevent
unintentional writes when VCC is greater than VLKO
Sector protection/unprotection must be implemented
using programming equipment. The procedure requires a high
voltage (VID) on address pin A9 and the control pins.
The device is shipped with all sectors unprotected. It is
possible to determine whether a sector is protected or
unprotected. See “Autoselect Mode” for details.
.
Write Pulse “Glitch” Protection
Noise pulses of less than 5 ns (typical) on OE\, CEx\ or
WEx\ do not initiate a write cycle.
Hardware Data Protection
The command sequence requirement of unlock cycles for
programming or erasing provides data protection against
inadvertent writes (refer to the Command Definitions table). In
addition, the following hardware data protection measures
prevent accidental erasure or programming, which might
otherwise be caused by spurious system level signals during
Logical Inhibit
Write cycles are inhibited by holding any one of OE\ = VIL,
CEx\ = VIH or WEx\ = VIH. To initiate a write cycle, CEx\ and
WEx\ must be a logical zero while OE\ is a logical one.
VCC power-up and power-down transitions, or from system
noise.
Power-Up Write Inhibit
If WEx\ = CEx\ = VIL and OE\ = VIH during power up, the device
does not accept commands on the rising edge of WEx\. The
internal state machine is automatical ly reset to reading array
data on power-up.
TABLE 3: Autoselect Codes (High Voltage Method)
I/O0 to I/O7
I/O8 to I/O15
I/O16 to I/O23
I/O24 to I/O31
A16 A13
to to
A14 A10
A5
A8 to
A7
DESCRIPTION
CEx\ OE\ WEx\
A9
A6 to A1 A0
A2
L
L
L
L
H
H
X
X
X
X
V
V
X
X
L
L
X
X
L
L
L
01h
ID
Manufacturer ID: AMD
Device ID: AM29F010B
H
20h
ID
01h (protected)
L
L
H
SA
X
V
X
L
X
H
L
ID
00h
(unprotected)
Sector Protection Verification
LEGEND:
L = Logic Low = VIL, H = Logic High = VIH, SA = Sector Address, X = Don’t care.
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
AS8F128K32
Rev. 2.0 5/03
5
AUSTIN [ AUSTIN SEMICONDUCTOR ]
