AM29BDS640G datasheet(31/77 Pages) AMD

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May 9, 2006 25903C2

Am29BDS640G

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Sheet

Standard Handshaking Operation

For optimal burst mode performance on devices without the handshaking option,

the host system must set the appropriate number of wait states in the flash de-

vice depending on the clock frequency.

Table 10 describes the typical number of clock cycles (wait states) for various

conditions with A14–A12 set to 101.

Table 10. Wait States for Standard Handshaking

* 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).

Burst Read Mode Configuration

The device supports four different burst read modes: continuous mode, and 8,

16, and 32 word linear wrap around modes. A continuous sequence begins at the

starting address and advances the address pointer until the burst operation is

complete. If the highest address in the device is reached during the continuous

burst read mode, the address pointer wraps around to the lowest address.

For example, an eight-word linear burst with wrap around begins on the starting

burst address written to the device and then proceeds until the next 8 word

boundary. The address pointer then returns to the first word of the burst se-

quence, wrapping back to the starting location. The sixteen- and thirty-two linear

wrap around modes operate in a fashion similar to the eight-word mode.

Table 11 shows the address bits and settings for the four burst read modes.

Table 11. Burst Read Mode Settings

Note: Upon power-up or hardware reset the default setting is continuous.

Burst Active Clock Edge Configuration

By default, the device will deliver data on the rising edge of the clock after the

initial synchronous access time. Subsequent outputs will also be on the following

rising edges, barring any delays. The device can be set so that the falling clock

Conditions at Address

Typical No. of Clock Cycles after

AVD# Low

40/54 MHz

Initial address is even

Initial address is odd

Initial address is even,

and is at boundary crossing*

Initial address is odd,

and is at boundary crossing*

Burst Modes

Address Bits

A16

A15

Continuous

8-word linear wrap around

16-word linear wrap around

32-word linear wrap around

AM29BDS640G Datasheet(PDF) 31 Page - Advanced Micro Devices

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