AM29DL640D datasheet(29/54 Pages) AMD

29 / 54 page

Am29DL640D

October 7, 2004

WRITE OPERATION STATUS

The device provides several bits to determine the status of a

program or erase operation: DQ2, DQ3, DQ5, DQ6, and

DQ7. Table 13 and the following subsections describe the

function of these bits. DQ7 and DQ6 each offer a method for

determining whether a program or erase operation is com-

plete or in progress. The device also provides a

hardware-based output signal, RY/BY#, to determine

whether an Embedded Program or Erase operation is in

progress or has been completed.

DQ7: Data# Polling

The Data# Polling bit, DQ7, indicates to the host system

whether an Embedded Program or Erase algorithm is in

progress or completed, or whether a bank is in Erase Sus-

pend. Data# Polling is valid after the rising edge of the final

WE# pulse in the command sequence.

During the Embedded Program algorithm, the device out-

puts on DQ7 the complement of the datum programmed 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 ac-

tive for approximately 1 µs, then that bank returns to the

read mode.

During the Embedded Erase algorithm, Data# Polling

produces a “0” on DQ7. When the Embedded Erase

algorithm is complete, or if the bank enters the Erase

Suspend mode, Data# Polling produces a “1” on DQ7.

The system must provide an address within any of the

sectors selected for erasure to read valid status infor-

mation on DQ7.

After an erase command sequence is written, if all

sectors selected for erasing are protected, Data# Poll-

ing on DQ7 is active for approximately 100 µs, then the

bank returns to the read mode. If not all selected sec-

tors are protected, the Embedded Erase algorithm

erases the unprotected sectors, and ignores the se-

lected sectors that are protected. However, if the

system reads DQ7 at an address within a protected

sector, the status may not be valid.

When the system detects DQ7 has changed from the

complement to true data, it can read valid data at

DQ15–DQ0 (or DQ7–DQ0 for x8-only device) on the

following read cycles. Just prior to the completion of an

Embedded Program or Erase operation, DQ7 may

change asynchronously with DQ8–DQ15 (DQ0–-DQ7

for x8-only device) while Output Enable (OE#) is as-

ser ted low. That is, the device may change from

providing status information to valid data on DQ7. De-

pending on when the system samples the DQ7 output,

it may read the status or valid data. Even if the device

has completed the program or erase operation and

DQ7 has valid data, the data outputs on DQ0–DQ15

may be still invalid. Valid data on DQ0–DQ15 (or

DQ0–DQ7 for x8-only device) will appear on succes-

sive read cycles.

Table 13 shows the outputs for Data# Polling on DQ7.

Figure 6 shows the Data# Polling algorithm. Figure 22

in the AC Characteristics section shows the Data#

Polling timing diagram.

Figure 6.

Data# Polling Algorithm

DQ7 = Data?

Yes

DQ5 = 1?

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 any sector address

within the sector being erased. 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.

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