
14
P/N:PM0732
MX29LV004T/B
REV. 1.1, SEP. 19, 2001
BY. Table 10 and the f ollowing subsections describe the
functions of these bits. Q7, R Y/BY, and DQ6 each off er
a method for determining whether a program or erase
operation is complete or in progress. These three bits
are discussed first. Please note that RY/BY pin is pro-
vided f or 40-pin TSOP pac kage type only.
Q7: Data Polling
The Data Polling bit, Q7, indicates to the host sys-tem
whether an Automatic Algorithm is in progress or com-
pleted, or whether the device is in Erase Suspend. Data
P olling is valid after the rising edge of the final WE pulse
in the program or erase command sequence.
During the Automatic Program algorithm, the device out-
puts on Q7 the complement of the datum programmed
to Q7. This Q7 status also applies to progr amming dur-
ing Er ase Suspend. When the Automatic Program algo-
rithm is complete, the device outputs the datum pro-
gr ammed to Q7. The system must provide the program
address to read valid status information on Q7. If a pro-
gr am address falls within a protected sector, Data Poll-
ing on Q7 is active for approximately 1 us, then the de-
vice returns to reading array data.
During the Automatic Erase algorithm, Data Polling pro-
duces a "0" on Q7. When the Automatic Erase algo-
rithm is complete, or if the device enters the Erase Sus-
pend mode, Data Polling produces a "1" on Q7. This is
analogous to the complement/true datum out-put de-
scribed for the Automatic 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 sec-
tors selected for erasure to read valid status information
on Q7.
After an erase command sequence is written, if all sec-
tors selected f or erasing are protected, Data P olling on
Q7 is active for approximately 100 us, then the device
returns to reading array data. If not all selected sectors
are protected, the Automatic Erase algorithm erases the
unprotected sectors, and ignores the selected sectors
that are protected.
When the system detects Q7 has changed from the
complement to true data, it can read valid data at Q7-Q0
on the following read cycles. This is because Q7 may
change asynchr onously with Q0-Q6 while Output En-
ab le (OE) is asserted low .
RY/BY:Ready/Busy (f or 40-pin TSOP package only)
The RY/BY is a dedicated, open-drain output pin that
indicates whether an Automatic Erase/Program algorithm
is in progress or complete. The RY/BY status is valid
after the rising edge of the final WE or CE, whichever
happens first, in the command sequence. Since R Y/BY
is an open-drain output, se veral R Y/BY pins can be tied
together in parallel with a pull-up resistor to Vcc.
If the output is low (Busy), the device is actively erasing
or programming. (This includes programming in the Erase
Suspend mode.)If the output is high (Ready), the device
is ready to read array data (including during the Erase
Suspend mode), or is in the standby mode.
Table 7 shows the outputs for R Y/BY during write opera-
tion.
Q6:Toggle BIT I
Toggle Bit I on Q6 indicates whether an A utomatic Pro-
gram or Erase algorithm is in progress or complete, or
whether the device has entered the Erase Suspend mode.
Toggle Bit I may be read at any address, and is valid
after the rising edge of the final WE or CE, whichever
happens first, in the command sequence(prior to the pro-
gram or erase operation), and during the sector time-
out.
During an Automatic Program or Erase algorithm opera-
tion, successive read cycles to any address cause Q6
to toggle. The system ma y use either OE or CE to con-
trol the read cycles. When the operation is complete, Q6
stops toggling.
After an erase command sequence is written, if all sec-
tors selected for erasing are protected, Q6 toggles and
returns to reading array data. If not all selected sectors
are protected, the Automatic Erase algorithm erases the
unprotected sectors, and ignores the selected sectors
that are protected.
The system can use Q6 and Q2 together to determine
whether a sector is actively erasing or is erase sus-
pended. When the device is actively erasing (that is, the
Automatic Erase algorithm is in progress), Q6 toggling.
When the device enters the Erase Suspend mode, Q6
stops toggling. Howe v er, the system m ust also use Q2
to determine which sectors are erasing or erase-sus-
pended. Alternatively, the system can use Q7.