10

MS7200L/7201AL/7202AL

MOSEL VITELIC

MS7200L/01AL/02AL Rev. 1.0 January 1995

Width Expansion Mode

Word width may be expanded by connecting the

corresponding control input signals of multiple

devices together. The EMPTY, HALF FULL and

FULL FLAGS (

EE, HF and FF) can be detected by

any particular device. Figure 4 shows an 18 bit wide

configuration using two devices. They may be

configured to any word width in this manner.

Figure 4. Width Expansion Mode

NOTES:

Flag detection is accomplished by monitoring the

EF, HF and EF pins on the device used in

the Width Expansion Mode. Do not connect output control signals together.

DATA IN

WRITE

READ

FULL FLAG

RESET

(W)

(D)

(FF)

(RS)

(R)

(Q)

(EF)

(RT)

MS

7201A

BITS

0-8

MS

7201A

BITS

9-17

DATA OUT

XI

9

9

9

9

18

18

EMPTY FLAG

XI

RETRANSMIT

(HF) HALF FULL FLAG

HALF FULL FLAG (HF)

Depth Expansion (Daisy Chain) Mode

Word depths may be expanded in multiples of

512 words by Daisy Chaining the devices together

as follows:

1. The FIRST LOAD (

FL) control signal of the first

device must be grounded. This FIFO repre-

sents word 1-512.

2. All other devices in the Daisy Chain must have

the FIRST LOAD (

FL) control signal tied to V

CC

in the inactive-high state.

3. The EXPANSION OUT (

XO) pin of each device

must be connected to the EXPANSION IN (

XI)

pin of the next device as shown in Figure 5.

4. External logic is required to generate a com-

mon FULL FLAG (

FF) and EMPTY FLAG (EF)

signal by ORing all of the

FFs together and

ORing all of the

EFs together.

5. The RETRANSMIT (

RT) fuction and HALF

FULL FLAG (

HF) are not available in Daisy

Chain Mode.

W

MS

7201

WORDS

1025-

1536

FF

EF

XO

MS

7201

WORDS

1513-

1024

FF

EF

XO

MS

7201

WORDS

1-512

FF

EF

XO

XI

XI

XI

FL

FL

FL

RS

FULL

D

Q

EMPTY

VCC

R

9

9

9

9

9

Figure 5. Diagram of a 1536 x 9 FIFO in Depth Expansion Mode