a29160 AMIC Technology Corporation, a29160 Datasheet - Page 11

• Manufacturer Part Number: a29160
• Description: 2m X 8 Bit / 1m X 16 Bit Cmos 5.0 Volt-only, Boot Sector Flash Memory
• Manufacturer: AMIC Technology Corporation

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.
It is possible to determine whether a sector is protected or
unprotected. See “Autoselect Mode” for details.
Sector protection / unprotection can be implemented via two
methods. The primary method requires V
only, and can be implemented either in-system or via
programming equipment. Figure 2 shows the algorithm and
the Sector Protect / Unprotect Timing Diagram illustrates the
timing waveforms for this feature. This method uses standard
microprocessor bus cycle timing. For sector unprotect, all
unprotected sectors must first be protected prior to the first
sector unprotect write cycle. The alternate method must be
implemented using programming equipment. The procedure
requires a high voltage (V
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.
Hardware Data Protection
The requirement of command unlocking sequence 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
V
is powered up to read array data to avoid accidentally writing
data to the array.
Write Protect (
The Write Protect function provides a hardware method of
protecting the 16Kbytes of boot sector from erasure without
using V
If the system asserts V
erase function for the 16Kbyte boot sector (SA34 for the top
boot device and SA0 for the bottom boot device)
independently of whether those sectors were protected or
unprotected
Protection/Unprotection.
If the system asserts V
whether the 16Kbyte boot sector was previously set to
protect or unprotected using the method described in Sector
Protection/Unprotection.
Low VCC Write Inhibit
When VCC is lower than V
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
V
control pins to prevent unintentional writes when VCC is
greater than V
(April, 2010, Version 0.2)
CC
LKO
power-up transitions, or from system noise. The device
. The system must provide the proper signals to the
ID .
LKO
using
.
WP
)
the
IH
IL
on the WP pin, the device disables
on the WP pin, the device reverts to
method
ID
LKO
) on address pin A9 and the
, the device does not accept
described
ID
on the RESET pin
in
Sector
10
Write Pulse "Glitch" Protection
Noise pulses of less than 5ns (typical) on
do not initiate a write cycle.
Logical Inhibit
Write cycles are inhibited by holding any one of
Power-Up Write Inhibit
If
device does not accept commands on the rising edge of
reading array data on the initial power-up.
Temporary Sector Unprotect
This feature allows temporary unprotection of previous
protected sectors to change data in-system. The Sector
Unprotect mode is activated by setting the RESET pin to V
During this mode, formerly protected sectors can be
programmed or erased by selecting the sector addresses.
Once V
protected sectors are protected again. Figure 1 shows the
algorithm, and the Temporary Sector Unprotect diagram
shows the timing waveforms, for this feature.
CE
WE
WE
WE
= V
Notes:
1. All protected sectors unprotected.
2. All previously protected sectors are protected once again.
. The internal state machine is automatically reset to
must be a logical zero while
Figure 1. Temporary Sector Unprotect Operation
ID
=
IH
is removed from the RESET pin, all the previously
CE
or
WE
= V
Program Operations
Completed (Note 2)
Temporary Sector
Perform Erase or
RESET = V
RESET = V
IL
= V
Unprotect
(Note 1)
START
and
IH
. To initiate a write cycle,
AMIC Technology, Corp.
OE
ID
IH
= V
OE
IH
A29160 Series
is a logical one.
during power up, the
OE
,
CE
OE
CE
or
=V
WE
and
ID
IL
,
.