Functional Description
Single Device Mode
A single M67204F may be used when the application requirements are for 4096 words
or less. The M67204F 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
(HALF-FULL FLAG)
(W)
(R)
(Q)
READ
)
WRITE
HF
9
9
DATAOUT
DATAIN
(I)
(EF)
EMPTY FLAG
RETRANSMIT
FULL FLAG (FF)
(RS)
(RT)
RESET
EXPANSION IN (XI)
M67204F
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 M67204F. Any word width can be
attained by adding additional M67204F.
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.
6
M67204F
4141F–AERO–06/02
ATMEL [ ATMEL ]
