
14
Am29F040B
21445E5
November 1, 2006
D A T A  S H E E T
WRITE OPERATION STATUS
The device provides several bits to determine the sta-
tus of a write operation: DQ2, DQ3, DQ5, DQ6, and 
DQ7. Table 
5
 and the following subsections describe 
the functions of these bits. DQ7 and DQ6 each offer a 
method for determining whether a program or erase 
operation is complete or in progress. These three bits 
are discussed first.
DQ7: Data# Polling
The Data# Polling bit, DQ7, indicates to the host sys-
tem whether an Embedded Algorithm is in progress or 
completed, or whether the device is in Erase Suspend. 
Data# Polling is valid after the rising edge of the final 
WE# pulse in the program or erase command 
sequence.
During the Embedded Program algorithm, the device 
outputs on DQ7 the complement of the datum pro-
grammed to DQ7. This DQ7 status also applies to 
programming during Erase Suspend. When the Em-
bedded Program algorithm is complete, the device 
outputs the datum programmed to DQ7. The system 
must provide the program address to read valid status 
information on DQ7. If a program address falls within a 
protected sector, Data# Polling on DQ7 is active for ap-
proximately 2 μs, then the device returns to reading 
array data.
During the Embedded Erase algorithm, Data# Polling 
produces a “0” on DQ7. When the Embedded Erase al-
gorithm is complete, or if the device enters the Erase 
Suspend mode, Data# Polling produces a “1” on DQ7. 
This is analogous to the complement/true datum output 
described for the Embedded Program algorithm: the 
erase function changes all the bits in a sector to “1”; 
prior to this, the device outputs the “complement,” or 
“0.” The system must provide an address within any of 
the sectors selected for erasure to read valid status in-
formation on DQ7.
After an erase command sequence is written, if all sec-
tors selected for erasing are protected, Data# Polling 
on DQ7 is active for approximately 100 μs, then the de-
vice returns to reading array data. If not all selected 
sectors are protected, the Embedded Erase algorithm 
erases the unprotected sectors, and ignores the se-
lected sectors that are protected.
When the system detects DQ7 has changed from the 
complement to true data, it can read valid data at 
DQ7–DQ0 on the 
following
 read cycles. This is be-
cause DQ7 may change asynchronously with 
DQ0–DQ6 while Output Enable (OE#) is asserted low. 
The Data# Polling Timings (During Embedded Algo-
rithms) figure in the 
“AC Characteristics”
 section 
illustrates this.
Table 
5
 shows the outputs for Data# Polling on DQ7. 
Figure
 3
 shows the Data# Polling algorithm.
DQ7 = Data
Yes
No
No
DQ5 = 1
No
Yes
Yes
FAIL
PASS
Read DQ7–DQ0
Addr = VA
Read DQ7–DQ0
Addr = VA
DQ7 = Data
START
Notes:
1. VA = Valid address for programming. During a sector 
erase operation, a valid address is an address within any 
sector selected for erasure. During chip erase, a valid 
address is any non-protected sector address.
2. DQ7 should be rechecked even if DQ5 = “1” because 
DQ7 may change simultaneously with DQ5.
 Figure 3. Data# Polling Algorithm