P r e l i m i n a r y
Power-up/
Hardware Reset
Asynchronous Read
Mode Only
Set Burst Mode
Set Burst Mode
Configuration Register
Command for
Configuration Register
Command for
Synchronous Mode
(A19 = 0)
Asynchronous Mode
(A19 = 1)
Synchronous Read
Mode Only
Figure 1. Synchronous/Asynchronous State Diagram
Read Mode Setting
On power-up or hardware reset, the device is set to be in asynchronous read
mode. This setting allows the system to enable or disable burst mode during sys-
tem operations. Address A19 determines this setting: “1’ for asynchronous mode,
“0” for synchronous mode.
Programmable Wait State Configuration
The programmable wait state feature informs the device of the number of clock
cycles that must elapse after AVD# is driven active before data will be available.
This value is determined by the input frequency of the device. Address bits A14–
A12 determine the setting (see Table 8).
The wait state command sequence instructs the device to set a particular number
of clock cycles for the initial access in burst mode. The number of wait states that
should be programmed into the device is directly related to the clock frequency.
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Am29BDS320G
27243B1 October 1, 2003
SPANSION [ SPANSION ]
