D A T A S H E E T
WRITE OPERATION STATUS
The device provides several bits to determine the
status of a write operation: DQ2, DQ3, DQ5, DQ6,
DQ7, and RY/BY#. Table 6 and the following subsec-
tions describe the functions of these bits. DQ7, RY/
BY#, 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.
Table 6 shows the outputs for Data# Polling on DQ7.
Figure 4 shows the Data# Polling algorithm.
START
DQ7: Data# Polling
The Data# Polling bit, DQ7, indicates to the host
system whether an Embedded Algorithm is in progress
or completed, or whether the device is in Erase Sus-
pend. Data# Polling is valid after the rising edge of the
final WE# pulse in the program or erase command
sequence.
Read DQ7–DQ0
Addr = VA
Yes
DQ7 = Data?
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
Embedded 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
approximately 2 µs, then the device returns to reading
array data.
No
No
DQ5 = 1?
Yes
Read DQ7–DQ0
Addr = VA
During the Embedded Erase algorithm, Data# Polling
produces a “0” on DQ7. When the Embedded Erase
algorithm 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
information on DQ7.
Yes
DQ7 = Data?
No
PASS
FAIL
After an erase command sequence is written, if all
sectors selected for erasing are protected, Data#
Polling on DQ7 is active for approximately 100 µs, then
the device returns to reading array data. If not all
selected sectors are protected, the Embedded Erase
algorithm erases the unprotected sectors, and ignores
the selected sectors that are protected.
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.
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
because DQ7 may change asynchronously with
DQ0–DQ6 while Output Enable (OE#) is asserted low.
Figure 15, Data# Polling Timings (During Embedded
Algorithms), in the “AC Characteristics” section illus-
trates this.
Figure 4. Data# Polling Algorithm
18
Am29F400B
21505E8 November 11, 2009
CYPRESS [ CYPRESS ]
