AM29BDS640G datasheet(30/65 Pages) SPANSION

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Am29BDS640G

25903C1 October 1, 2003

Prelimin ary

Table 8. Programmable Wait State Settings

Notes:

1. Upon power-up or hardware reset, the default setting is seven wait states.

2. RDY will default to being active with data when the Wait State Setting is set to a

total initial access cycle of 2.

3. Assumes even address.

It is recommended that the wait state command sequence be written, even if the

default wait state value is desired, to ensure the device is set as expected. A

hardware reset will set the wait state to the default setting.

Reduced Wait-State Handshaking Option

If the device is equipped with the reduced wait-state handshaking option, the

host system should set address bits A14–A12 to 010 for a clock frequency of 40

MHz or to 011 for a clock frequency of 54 MHz for the system/device to execute

at maximum speed.

Table 9 describes the typical number of clock cycles (wait states) for various

conditions.

Table 9. Initial Access Cycles vs. Frequency

Note: In the 8-, 16- and 32-word burst read modes, the address pointer does not

cross 64-word boundaries (addresses which are multiples of 3Fh).

The autoselect function allows the host system to determine whether the flash

device is enabled for reduced wait-state handshaking. See the “Autoselect Com-

mand Sequence” section for more information.

A14

A13

A12

Total Initial

Access Cycles

System

Frequency

Range

Even

Initial

Addr.

Odd

Initial

Addr.

Even

Initial

Addr.

with

Boundary

Odd Initial

Addr.

with

Boundary

Device Speed

Rating

6–11 MHz

40 MHz

12–23 MHz

24–33 MHz

34–40 MHz

40–47 MHz

54 MHz

48–54 MHz

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