SN74ALS2238

32 × 9 × 2 ASYNCHRONOUS BIDIRECTIONAL FIRST IN, FIRST OUT MEMORY

SDAS182 − APRIL 1990

6

POST OFFICE BOX 655303

POST OFFICE BOX 1443

SELECT-MODE CONTROL TABLE

CONTROL

OPERATION

SAB

SBA

A BUS

B BUS

L

L

Real-time B to A bus

Real-time A to B bus

L

H

FIFO B to A bus

Real-time A to B bus

H

L

Real-time B to A bus

FIFO A to B bus

H

H

FIFO B to A bus

FIFO A to B bus

OUTPUT-ENABLE CONTROL TABLE

CONTROL

OPERATION

GAB

GBA

A BUS

B BUS

H

H

A bus enabled

B bus enabled

L

H

A bus enabled

Isolation/ input to B bus

H

L

Isolation / input to A bus

B bus enabled

L

L

Isolation / input to A bus

Isolation/ input to B bus

Program:

Step 1.

With RSTA at a high level, take DAF from a high level to a low level. The high-to-low transition on

DAF stores the binary value of A0 −A4 for use as the value of X in defining the depth of FIFO A.

Step 2.

With DAF held low, pulse the RSTA signal low. On the low-to-high transition of RSTA, FIFO A is set

to a depth of 32 − X, where X is the value of A0 −A4 stored above.

Step 3.

To redefine the depth of FIFO A to 32 words, hold DAF at a high level and pulse the RSTA signal low.

† The programming procedures used to define the depth of FIFO B are the same as the procedure above.

−0.5 V to 7 V

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Input voltage: Control inputs

7 V

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

I/O ports

5.5 V

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Voltage applied to a disabled 3-state output

5.5 V

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

0

°C to 70°C

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Storage temperature range

−65

°C to 150°C

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Maximum junction temperature

150

°C

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

‡ Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and

functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not

implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.