1Mx36 & 2Mx18 Synchronous SRAM

- 6 -

Rev 2.0

Nov. 2003

K7A321800M

K7A323600M

FUNCTION DESCRIPTION

The K7A323600M and K7A321800M are synchronous SRAM designed to support the burst address accessing sequence of the

Power PC based microprocessor. All inputs (with the exception of OE, LBO and ZZ) are sampled on rising clock edges. The start and

duration of the burst access is controlled by ADSC, ADSP and ADV and chip select pins.

The accesses are enabled with the chip select signals and output enabled signals. Wait states are inserted into the access with

ADV.

When ZZ is pulled high, the SRAM will enter a Power Down State. At this time, internal state of the SRAM is preserved. When ZZ

returns to low, the SRAM normally operates after 2cycles of wake up time. ZZ pin is pulled down internally.

Read cycles are initiated with ADSP(regardless of WEx and ADSC)using the new external address clocked into the on-chip address

register whenever ADSP is sampled low, the chip selects are sampled active, and the output buffer is enabled with OE. In read oper-

ation the data of cell array accessed by the current address, registered in the Data-out registers by the positive edge of CLK, are car-

ried to the Data-out buffer by the next positive edge of CLK. The data, registered in the Data-out buffer, are projected to the output

pins. ADV is ignored on the clock edge that samples ADSP asserted, but is sampled on the subsequent clock edges. The address

increases internally for the next access of the burst when WEx are sampled High and ADV is sampled low. And ADSP is blocked to

All byte write is done by GW(regaedless of BW and WEx.), and each byte write is performed by the combination of BW and WEx

when GW is high.

Write cycles are performed by disabling the output buffers with OE and asserting WEx. WEx are ignored on the clock edge that sam-

ples ADSP low, but are sampled on the subsequent clock edges. The output buffers are disabled when WEx are sampled

Low(regaedless of OE). Data is clocked into the data input register when WE x sampled Low. The address increases internally to the

next address of burst, if both WEx and ADV are sampled Low. Individual byte write cycles are performed by any one or more byte

ated with ADSC, instead of ADSP. The differences between cycles initiated with ADSC and ADSP as are follows;

ADSP must be sampled high when ADSC is sampled low to initiate a cycle with ADSC.

WEx are sampled on the same clock edge that sampled ADSC low(and ADSP high).

Addresses are generated for the burst access as shown below, The starting point of the burst sequence is provided by the external

address. The burst address counter wraps around to its initial state upon completion. The burst sequence is determined by the state

of the LBO pin. When this pin is Low, linear burst sequence is selected. When this pin is High, Interleaved burst sequence is

selected.

BURST SEQUENCE TABLE

(Interleaved Burst)

LBO PIN

HIGH

Case 1

Case 2

Case 3

Case 4

First Address

Fourth Address

0

0

1

1

0

1

0

1

0

0

1

1

1

0

1

0

1

1

0

0

0

1

0

1

1

1

0

0

1

0

1

0

BQ TABLE

(Linear Burst)

Note : 1. LBO pin must be tied to High or Low, and Floating State must not be allowed

.

LBO PIN

LOW

Case 1

Case 2

Case 3

Case 4

First Address

Fourth Address

0

0

1

1

0

1

0

1

0

1

1

0

1

0

1

0

1

1

0

0

0

1

0

1

1

0

0

1

1

0

1

0

ASYNCHRONOUS TRUTH TABLE

Operation

ZZ

OE

I/O STATUS

Sleep Mode

H

X

High-Z

Read

L

L

DQ

L

H

High-Z

Write

L

X

Din, High-Z

Deselected

L

X

High-Z

Notes

1. X means "Don

2. ZZ pin is pulled down internally

3. For write cycles that following read cycles, the output buffers must be

disabled with OE , otherwise data bus contention will occur.

4. Sleep Mode means power down state of which stand-by current does

not depend on cycle time.

5. Deselected means power down state of which stand-by current

depends on cycle time.