MSM5412222A-25JS データシートの表示（PDF） - Oki Electric Industry

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MSM5412222A-25JS

262,214-Word x 12-Bit Field Memory

Oki Electric Industry 

OKI Semiconductor

MSM5412222A

Read Operation

The read operation is controlled by three clocks, SRCK, RSTR, and RE. Read operation is

accomplished by cycling SRCK, and holding RE high after the read address pointer reset

operation or RSTR.

Each read operation, which begins after RSTR, must contain at least 80 active read cycles,

i.e. SRCK cycles while RE is high.

Read Reset : RSTR

The first positive transition of SRCK after RSTR becomes high resets the read address

counters to zero. RSTR setup and hold times are referenced to the rising edge of SRCK.

Because the read reset function is solely controlled by the SRCK rising edge after the high

level of RSTR, the states of RE and OE are ignored in the read reset cycle.

Before RSTR may be brought high again for a further reset operation, it must be low for at

least *two SRCK cycles.

Data Out : DOUT 0 - 11

Read Clock : SRCK

Data is shifted out of the data registers. It is triggered by the rising edge of SRCK when RE

is high during a read operation. The SRCK input increments the internal read address

pointer when RE is high.

The three-state output buffer provides direct TTL compatibility ( no pullup resistor required).

Data out is the same polarity as data in. The output becomes valid after the access time

interval tAC that begins with the rising edge of SRCK. *There are no output valid time

restriction on MSM5412222A.

Read Enable : RE

The function of RE is to gate of the SRCK clock for incrementing the read pointer. When RE

is high before the rising edge of SRCK, the read pointer is incremented. When RE is low, the

read pointer is not incremented. RE setup times (tRENS and tRDSS ) and RE hold times (tRENH

and tRDSH ) are referenced to the rising edge of the SRCK clock.

Output Enable : OE

OE is used to enable/disable the outputs. OE high level enables the outputs. The internal

read address pointer is always incremented by cycling SRCK regardless of the OE level.

Note that OE setup and hold times are referenced to the rising edge of SRCK.

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