IS61DDB22M18A

IS61DDB21M36A

Integrated Silicon Solution, Inc.- www.issi.com

Rev. B

10/02/2014

10

Timing Reference Diagram for Truth Table

The Timing Reference Diagram for Truth Table is helpful in understanding the Clock and Write Truth Tables, as it

shows the cycle relationship between clocks, address, data in, data out, and control signals. Read command is issued

at the beginning of cycle “t”. Write command is issued at the beginning of cycle “t+1”.

DB

DB+1

QA

QA+1

t + 1

t

t + 2

t + 3

t + 4

t + 5

A

B

Cycle

K Clock

K# Clock

LD#

R/W#

Address

Data-

In/Out(DQ)

CQ

CQ#

C Clock

C# Clock

tCHQV

Clock Truth Table

(Use the following table with the Timing Reference Diagram for Truth Table.)

Mode

Clock

Controls

Data Out / Data In

K

LD#

R/W#

Stop Clock

Stop

X

X

Previous State

Previous State

No

Operation

(NOP)

L

→ H

H

X

High-Z

High-Z

Read A

L → H

L

H

Write B

L → H

L

L

Notes:

1.

X = “don’t care”; H = logic “1”; L = logic “0”.

2.

A read operation is started when control signal R/W# is active high.

3.

A write operation is started when control signal R/W# is active low.

4.

Before entering into stop clock, all pending read and write commands must be completed.

5.

For timing definitions, refer to the AC Timing Characteristics table. Signals must meet AC specifications at timings indicated in parenthesis with

respect to switching clocks K,K#,C, and C#.