6

M67204H

4141J–AERO–04/07

Functional Description

Single Device Mode

A single M67204H may be used when the application requirements are for 4096 words

or less. The M67204H is in a Single Device Configuration when the Expansion In (XI) control

input is grounded (see Figure 2). In this mode the Half-Full Flag (HF), which is an active low out-

put, is shared with Expansion Out (XO).

Figure 2. Block Diagram of Single 4096 bits x 9

Width Expansion Mode

Word width may be increased simply by connecting the corresponding input control sig-

nals of multiple devices. Status flags (EF, FF and HF) can be detected from any device.

Figure 3 demonstrates an 18-bit word width by using two M67204H. Any word width can be

attained by adding additional M67204H.

Figure 3. Block Diagram of 4096 bits × 18 FIFO Memory Used in Width Expansion Mode

Note:

Flag detection is accomplished by monitoring the FF, EF and the HF signals on either (any) device used in the width expansion

configuration. Do not connect any output control signals together.

)

WRITE

(W)

(R)

READ

DATA

IN

9

(I)

DATA

OUT

9

(Q)

FULL FLAG

RESET

(FF)

(RS)

EMPTY FLAG

RETRANSMIT

(EF)

(RT)

EXPANSION IN (XI)

HF

M67204H

(HALF-FULL FLAG)