HIT HD74HC623, HD74HC620 Datasheet

HD74HC620/HD74HC623

Octal Bus Transceivers (with inverted 3-state outputs)

Octal Bus Transceivers (with 3-state outputs)

Description

This octal bus transceiver is designed for asynchronous two-way communication between data buses. The
control fuction implementation allows for maximum flexibility in timing.

This device allows data transmission from the A bus to the B bus or from the B bus to the A bus depending
upon the logic levels at the enable inputs (GBA and GAB).

The enable inputs can be used to disable the device so that the buses are effectively isolated.

The dual-enable configuration gives these devices the capability to store data by simultaneous enabling of
GBA and GAB. Each output reinforces its input in this transceiver configuration. Thus, when both control
inputs are enabled and all other data sources to the two sets of bus lines are at high impedance, both sets of
bus lines (16 in all) will remain at their last states. The 8-bit codes appearing on the two sets of buses will
be identical for the HD74HC623 or coplementary for the HD74HC620.

Features

• High Speed Operation: tpd (Bus to Bus) = 12 ns typ (CL = 50 pF)

• High Output Current: Fanout of 15 LSTTL Loads

• Wide Operating Voltage: VCC = 2 to 6 V

• Low Input Current: 1 µA max

• Low Quiescent Supply Current: ICC (static) = 4 µA max (Ta = 25°C)

Function Table

Enable Inputs Operation
GBA GAB HD74HC620 HD74HC623

LLB data to A bus B data to A bus
HHA data to B bus A data to B bus
H L Isolation Isolation
LHB data to A bus, A data to B bus B data to A bus, A data to B bus

HD74HC620/HD74HC623

Pin Arrangement

Enable GAB V

A1

A2

A3

A4

A

A6

A7

A8

GND

Absolute Maximum Ratings

1

2

3

4

5

5

6

7

8

9

10 11

(Top view)

20

CC

Enable GBA

19

18

1

B

17

B2

16

B3

15

B

4

14

B5

13

B6

12

B7

B8

Item Symbol Rating Unit

Supply voltage range V
Input voltage V
Output voltage V
Output current I

CC

IN

OUT

OUT

DC current drain per VCC GND ICC, I
DC input diode current I
DC output diode current I
Power Dissipation per package P

IK

OK

T

GND

–0.5 to +7.0 V
–0.5 to VCC + 0.5 V
–0.5 to VCC + 0.5 V

±35 mA
±75 mA
±20 mA
±20 mA

500 mW

Storage temperature Tstg –65 to +150 °C

2

Block Diagram

HD74HC620

GBA

GAB

HD74HC620/HD74HC623

VCC

A1

A2

A3

A4

A5

A6

B1

VCC

B2

B3

B4

B5

B6

A7

B7

B8A8

3