AM29F016B datasheet(18/38 Pages) AMD

18 / 38 page

Am29F016B

P R E L I M I NARY

WRITE OPERATION STATUS

The device provides several bits to determine the sta-

tus of a write operation: DQ2, DQ3, DQ5, DQ6, DQ7,

and RY/BY#. Table 6 and the following subsections de-

scribe 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.

DQ7: Data# Polling

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

sys tem whether an Embe dded Algor ith m 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 pro-

g r amm i n g dur ing Er a s e S u s p end. W h e n 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 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 because DQ7

may change asynchronously with DQ0–DQ6 while

Output Enable (OE#) is asserted low. The Data# Poll-

ing Timings (During Embedded Algorithms) figure in

the “AC Characteristics” section illustrates this.

Table 6 shows the outputs for Data# Polling on DQ7.

Figure 4 shows the 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 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.

21444B-11

Figure 4.

Data# Polling Algorithm

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