HD74BC640A
Octal Bus Transceivers With 3 State Outputs
ADE-205-026 (Z)
1st. Edition
Feb. 1994
Description
The HD74BC640A provides high drivability and operation equal to or better than high speed bipolar
standard logic IC by using Bi-CMOS process. The device features low power dissipation that is about 1/5
of high speed bipolar logic IC. When the frequency is 10 MHz. The device has eight bus transceivers with
three state outputs in a 20 pin package. Each device has an active low enable input (G) and a direction
control input, DiR. When DiR is high, data flows from the A inputs to the B outputs. When DiR is high,
data flows from the B inputs to the A outputs. When enable inputs (G) is high, disables both A and B ports
by placing then in a high impedance.
Features
鈥?/div>
Input/Output are at high impedance state when power supply is off.
鈥?/div>
Input pins can be open, when not used, owing to built in input pull up circuit.
鈥?/div>
Input is TTL level.
鈥?/div>
Wide operating temperature range
Ta = 鈥?0 to +85擄C.
Function Table
Control Inputs
G
L
L
H
H :
L :
X :
High level
Low level
Immaterial
DIR
L
H
X
Operation
B
data to A bus
A
data to B bus
Isolation
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