SN74BCT2423A, SN74BCT2424A

16-BIT LATCHED MULTIPLEXER/DEMULTIPLEXER BUS TRANSCEIVERS

SDIS013 – JULY 1989 – REVISED AUGUST 1990

7

POST OFFICE BOX 655303

Terminal Functions

TERMINAL PINS

DESCRIPTION

A15 – A0

A bus. This 16-bit I/O port allows for transmission of data and/or address information to or from the AB bus.

Information transfer between the A bus and the AB bus is inverting for the ’BCT2423A and noninverting for the

’BCT2424A.

AB 15 – AB 0

(’BCT 2423A)

AB 15 – AB 0

(’BCT 2424A)

AB Bus. This 16-bit i/o port allows for multiplexed transmission of data and/or address information to or from the A

and B buses. Information transfer between the A, B, and AB buses is inverting for the ’BCT2423A and noninverting

for the ’BCT2424A.

ABENL

AB Bus Output Enable, Least Significant Byte. This active-low input is used to enable the AB7 – AB0 outputs. When

this input is high, the AB7 – AB0 outputs are in the high-impedance state allowing for data input.

ABENM

AB Bus Latch Enable, Most Significant Byte. This active-low input is used to enable the AB15–AB8 outputs. When

this input is high, the AB15 –AB8 outputs are in the high-impedance state allowing for data input.

ABLEA

AB Bus Latch Enable to A Bus. This active-low input is used to control the latch that holds data received from the

AB bus (AB15 –AB0) to be transferred to the A bus (A15 –A0). When ABLEA is low, the latch is transparent. When

ABLEA transitions to the high level, the data present at the AB15 – AB0 inputs is latched, and it remains latched while

ABLEA is high.

ABLEB

AB Bus Latch Enable to B Bus. This active-low input is used to control the latch that holds data received from the

AB bus (AB15 –AB0) to be transferred to the B bus (B15–B0). When ABLEB is low, the latch is transparent. When

ABLEB transitions to the high level, the data present at the AB15 – AB0 inputs is latched, and it remains latched while

ABLEB is high.

A / BSEL

A / B Select Control. This input controls the A / B multiplexer. When the input is low, the A15 – A0 is selected as input

to the AB15 – AB0 outputs. When the input is high, B15 – B0 is selected as input to the AB15 – AB0 outputs.

AENL

A Bus Output Enable, Least Significant Byte. This active-low input is used to enable the A7 – A0 outputs. When this

input is high, the A7 – A0 outputs are in the high-impedance state allowing for data input.

AENM

A Bus Output Enable, Most Significant Byte. This active-low input is used to enable the A15 – A8 outputs. When this

input is high, the A15 – A8 outputs are in the high-impedance state allowing for data input.

ALE

A Bus Latch Enable. This active-low input is used to control the latch that holds data received from the A bus

(A15 – A0). When ALE is low, that latch is transparent. When ALE transitions to the high level, the data present at

the A15 – A0 inputs is latched and remains latched while ALE is high.

B15 – B0

B Bus. This 16-bit I/O port allows for transmission of data and/or address information to or from the AB bus.

Information transfer between the B bus and the AB bus is inverting for the ’BCT2423A and noninverting for the

’BCT2424A.

BENL

B Bus Output Enable, Least Significant Byte. This active-low input is used to enable the B7 – B0 outputs. When this

input is high, the B7 – B0 outputs are in the high-impedance state allowing for data input.

BENM

B Bus Output Enable, Most Significant Byte. This active-low input is used to enable the B15 – B8 outputs. When this

input is high, the B15 – B8 outputs are in the high-impedance state allowing for data input.

BLE

B Bus Latch Enable. This active-low input is used to control the latch that holds data received from the B bus

(B15 – B0). When BLE is low, that latch is transparent. When BLE transitions to the high level, that data present at

the B15 – B0 inputs is latched and remains latched while BLE is high.