AM29BL802CB datasheet(17/46 Pages) AMD

17 / 46 page

November 3, 2006 22371C7

Am29BL802C

D A TA

SH EET

or while in the autoselect mode. See the “Reset Com-

mand” section, next.

See also “Requirements for Reading Array Data Array in

Asynchronous (Non-Burst) Mode” in the “Key to Switch-

ing Waveforms” section for more information. The Read

Operations table provides the read parameters, and Fig-

ure 15 shows the timing diagram.

Reading Array Data in Burst Mode

The device powers up in the non-burst mode. To read

array data in burst mode, the system must write the

four-cycle Burst Mode Enable command sequence

(see Table 4). The device then enters burst mode. In

addition to asserting CE#, OE#, and WE# control sig-

nals, burst mode operation requires that the system

provide appropriate LBA#, BAA#, and CLK signals. For

successful burst mode reads, the following events must

occur (refer to Figures 3 and 4 for this discussion):

1. The system asserts LBA# low, indicating to the de-

vice that a valid initial burst address is available on

the address bus. LBA# must be kept low until at

least the next rising edge of the CLK signal, upon

which the device loads the initial burst address.

2. The system returns LBA# to a logic high. The device

requires that the next rising edge of CLK occur with

LBA# high for proper burst mode operation. Typi-

cally, the initial number of CLK cycles depends on

the clock frequency and the rated speed of the de-

vice.

3. After the initial data has been read, the system as-

serts BAA# low to indicate it is ready to read the re-

maining burst read cycles. Each successive rising

edge of the CLK signal then causes the flash device

to increment the burst address and output sequen-

tial burst data.

4. When the device outputs the last word of data in the

32-word burst mode read sequence, the device out-

puts a logic low on the IND# pin. This indicates to

the system that the burst mode read sequence is

complete.

5. To exit the burst mode, the system must write the

four-cycle Burst Mode Disable command sequence.

The device will also exit the burst mode if powered

down or if RESET# is asserted. The device will not

exit the burst mode if the reset command is written.

Figure 3.

Burst Mode Read with 40 MHz CLK, 65 ns tIACC, 18 ns tBACC Parameters

CLK

LBA#

BAA#

Data

OE#

Step 1

Step 2

Step 3

25 ns

65 ns

25 ns

18 ns

Da +1

Da +2

18 ns

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