WEDPNF8M722V-1010BI 查看數據表（PDF） - White Electronic Designs Corporation

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WEDPNF8M722V-1010BI

8Mx72 Synchronous DRAM + 16Mb Flash Mixed Module Multi-Chip Package

White Electronic Designs Corporation 

White Electronic Designs WEDPNF8M722V-XBX

FIG. 4 CAS LATENCY

CAS LATENCY

The CAS latency is the delay, in clock cycles, between the

registration of a READ command and the availability of the

first piece of output data. The latency can be set to two or

three clocks.

If a READ command is registered at clock edge n, and the

latency is m clocks, the data will be available by clock edge

n+m. The I/Os will start driving as a result of the clock edge

one cycle earlier (n + m - 1), and provided that the rel-

evant access times are met, the data will be valid by clock

edge n + m. For example, assuming that the clock cycle

time is such that all relevant access times are met, if a READ

command is registered at T0 and the latency is programmed

to two clocks, the I/Os will start driving after T1 and the

data will be valid by T2. Table 2 indicates the operating fre-

quencies at which each CAS latency setting can be used.

Reserved states should not be used as unknown operation

or incompatibility with future versions may resuSELF SELF Test

modes and reserved states should not be used because

unknown operation or incompatibility with future versions

may result.

OPERATING MODE

The normal operating mode is selected by setting M7and M8

to zero; the other combinations of values for M7 and M8 are

reserved for future use and/or test modes. The programmed

burst length applies to both READ and WRITE bursts.

WRITE BURST MODE

When M9 = 0, the burst length programmed via M0-M2

applies to both READ and WRITE bursts; when M9 = 1, the

programmed burst length applies to READ bursts, but write

accesses are single-location (nonburst) accesses.

SPEED

-100

-125

TABLE 2 - CAS LATENCY

ALLOWABLE OPERATING

FREQUENCY (MHZ)

CAS

LATENCY = 2

CAS

LATENCY = 3

≤ 75

≤ 100

≤ 100

≤ 125

COMMANDS

The Truth Table provides a quick reference of available com-

mands. This is followed by a written description of each

command. Three additional Truth Tables appear following

the Operation section; these tables provide current state/

next state information.

White Electronic Designs Corporation • Phoenix AZ • (602) 437-1520

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