
A29L160A Series
(May, 2005, Version 0.1) 
10 
AMIC Technology, Corp.
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 VID on the 
RESET
pin 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 
equipment. The procedure requires a high voltage (V
ID
) 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.  
using 
programming 
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
CC
 power-up transitions, or from system noise. The device 
is powered up to read array data to avoid accidentally writing 
data to the array. 
Write Pulse "Glitch" Protection  
Noise pulses of less than 5ns (typical) on 
OE
 , 
CE
 or 
WE
do not initiate a write cycle.  
Logical Inhibit  
Write cycles are inhibited by holding any one of 
OE
 =V
IL
, 
CE
  = V
IH
 or 
WE
  = V
IH
. To initiate a write cycle, 
CE
  and 
WE
  must be a logical zero while 
OE
  is a logical one. 
Power-Up Write Inhibit  
If 
WE
  = 
CE
  = V
IL
 and 
OE
  = V
IH
 during power up, the 
device does not accept commands on the rising edge of 
WE
 . The internal state machine is automatically reset to 
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
ID
. 
During this mode, formerly protected sectors can be 
programmed or erased by selecting the sector addresses. 
Once V
ID
 is removed from the 
RESET
 pin, all the previously 
protected sectors are protected again. Figure 1 shows the 
algorithm, and the Temporary Sector Unprotect diagram 
shows the timing waveforms, for this feature. 
START
RESET = V
ID
(Note 1)
Perform Erase or
Program Operations
RESET = V
IH
Temporary Sector
Unprotect
Completed (Note 2)
Notes:
1. All protected sectors unprotected.
2. All previously protected sectors are protected once again.
Figure 1. Temporary Sector Unprotect Operation