Philips Semiconductors

Product specification

74F621

Octal bus transceiver, non-inverting (open collector)

2

1996 Jan 05

853–0380 16185

FEATURES

(20

µA in High and Low states)

DESCRIPTION

The 74F621 is an octal transceiver featuring non-inverting open

collector bus-compatible outputs in both send and receive

directions. The outputs are capable of sinking 64mA, providing very

good capacitive drive characteristics.

This octal bus transceiver is designed for asynchronous two-way

communication between data buses. The control function

implementation allows for maximum flexibility in timing.

The 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 (OEBA and OEAB). The Enable inputs can be used to

disable the device so that the buses are effectively isolated.

The dual-enable configuration gives the 74F621 the capability to

store data by the simultaneous enabling of OEBA and OEAB. 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 the bus lines are at high impedance, both sets of bus

lines (16 in all) will remain in their last states.

PIN CONFIGURATION

20

19

18

17

16

15

14

13

12

10

11

9

8

7

6

5

4

3

2

1

VCC

B1

B2

B3

B4

B5

B6

B7

OEAB

A1

A2

A3

A4

A5

A6

A7

GND

OEBA

A0

B0

SF01135

TYPE

TYPICAL

PROPAGATION

DELAY

TYPICAL SUPPLY CURRENT

(TOTAL)

74F621

8.0ns

105mA

ORDERING INFORMATION

DESCRIPTION

COMMERCIAL RANGE

PKG

DWG #

20-pin plastic DIP

N74F621N

SOT146-1

20-pin plastic SOL

N74F621D

SOT163-1

INPUT AND OUTPUT LOADING AND FAN-OUT TABLE

PINS

DESCRIPTION

74F(U.L.)

HIGH/LOW

LOAD VALUE

HIGH/LOW

A0 - A7, B0 - B7

Data inputs

1.0/0.033

20

µA/20µA

OEBA, OEAB

Output Enable inputs

1.0/0.033

20

µA/20µA

A0 - A7

Data outputs

OC/40

OC/24mA

B0 - B7

Data outputs

OC/106.7

OC/64mA

NOTE: One (1.0) FAST unit load is defined as: 20

µA in the High state and 0.6mA in the Low state. OC = Open Collector.