
A49LF004 
PRELIMINARY      (November, 2003, Version 0.0) 
11 
AMIC Technology, Corp.
Table 7: A/A Mux Mode Operation Selection
Block-Erase Operation 
The Block-Erase Operation allows the system to erase the 
device in 64 KByte uniform block size for the A49LF004. The 
Block-Erase operation is initiated by executing a six-byte 
command load sequence for Software Data Protection with 
Block-Erase command (30H or 50H) and block address. The 
internal Block-Erase operation begins after the sixth WE# pulse. 
The End-of-Erase can be determined using either Data# Polling 
or Toggle Bit methods. See Figure 15 for timing waveforms. 
Any commands written during the Block- Erase operation will 
be ignored. 
Chip-Erase 
The A49LF004 device provides a Chip-Erase operation only in 
A/A Mux mode, which allows the user to erase the entire 
memory array to the ‘1’s state. This is useful when the entire 
device must be quickly erased. The Chip-Erase operation is 
initiated by executing a six-byte Software Data Protection  
command sequence with Chip-Erase command (10H) with 
address 5555H in the last byte sequence. The internal Erase 
operation begins with the rising edge of the sixth WE#. During 
the internal Erase operation, the only valid read is Toggle Bit or 
Data# Polling. See Table 8 for the command sequence, Figure 
16 for timing diagram, and Figure 21 for the flowchart. Any 
commands written during the Chip-Erase operation will be 
ignored. 
Write Operation Status Detection 
The A49LF004 device provides two software means to detect 
the completion of a Write (Program or Erase) cycle, in  
order to optimize the system Write cycle time. The software 
detection includes two status bits: Data# Polling (I/O
7
) and 
Toggle Bit (I/O
6
). The End-of-Write detection mode is enabled 
after the rising edge of WE# which initiates the internal Program 
or Erase operation. The actual completion of the nonvolatile 
write is asynchronous with the system; therefore, either a Data# 
Polling or Toggle Bit read may be simultaneous with the 
completion of the Write cycle. If this occurs, the system may 
possibly get an erroneous result, i.e., valid data may appear to 
conflict with either I/O
7
 or I/O
6
. In order to prevent spurious 
rejection, if an erroneous result occurs, the software routine 
should include a loop to read the accessed location an 
additional two times. If both reads are valid, then the device has 
completed the Write cycle, otherwise the rejection is valid. 
Data# Polling (I/O
7
) 
When the A49LF004 device is in the internal Program operation, 
any attempt to read I/O
7
 will produce the complement of the 
true data. Once the Program operation is completed, I/O
7
 will 
produce true data. Note that even though I/O
7
 may have valid 
data immediately following the completion of an internal Write 
operation, the remaining data outputs may still be invalid: valid 
data on the entire data bus will appear in subsequent 
successive Read cycles after an interval of 1 μs. During internal 
Erase operation, any attempt to read I/O
7
 will produce a ‘0’. 
Once the internal Erase operation is completed, I/O
7
 will 
produce a ‘1’. The Data# Polling is valid after the rising edge of 
fourth WE# pulse for Program operation. For Block- or Chip-
Erase, the Data# Polling is valid after the rising edge of sixth 
WE# pulse. See Figure 12 for Data# Polling timing diagram. 
Proper status will not be given using Data# Polling if the 
address is in the invalid range. 
Toggle Bit (I/O
6
) 
During the internal Program or Erase operation, any 
consecutive attempts to read I/O
6
 will produce alternating ‘0’s 
and ‘1’s, i.e., toggling between 0 and 1. When the internal 
Program or Erase operation is completed, the toggling will stop. 
The device is then ready for the next operation. The Toggle Bit 
is valid after the rising edge of fourth WE# pulse for Program 
operation. For Block- or Chip-Erase, the Toggle Bit is valid after 
the rising edge of sixth WE# pulse. See Figure 13 for Toggle Bit 
timing diagram. 
Data Protection 
The A49LF004 device provides both hardware and software 
features to protect nonvolatile data from inadvertent writes. 
Hardware Data Protection 
Noise/Glitch Protection: A WE# pulse of less than 5 ns will not 
initiate a Write cycle.  
V
DD
 Power Up/Down Detection: The Write operation is inhibited 
when V
DD
 is less than 1.5V.  
Write Inhibit Mode: Forcing OE# low, WE# high will inhibit the 
Write operation. This prevents inadvertent writes during power-
up or power-down. 
Mode 
RST# 
OE# 
WE#
Address 
I/O 
Read 
V
IH
V
IH
V
IH
V
IH
V
IL
V
IL
V
IH
V
IH
V
IH
X 
V
IH
V
IL
V
IH
X 
A
IN
A
IN
X 
D
OUT
D
IN
High Z 
Write 
Standby 
Output Disable 
X 
High Z 
Reset 
X 
X 
High Z 
A21 – A2 = X, A1 = V
IL
, A0 = V
IL
Manufacturer ID 
A21 – A2 = X, A1 = V
IL
, A0 = V
IH
Device ID 
Product Identification 
V
IH
V
IL
V
IH
A21 – A2 = X, A1 = V
IH
, A0 = V
IH
Continuation ID