HD74BC620A
Octal Bus Transceivers With 3 State Outputs
ADE-205-024 (Z)
Rev. 0
June 1993
Description
The HD74BC620A 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. 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.
Features
Input/Output are at high impedance state when power supply is off.
Input pins can be open, when not used, owing to built in input pull up circuit.
Input is TTL level.
Wide operating temperature range
Ta = 40 to +85C.
Function Table
Enable Inputs
GBA
GAB
Operation
L
L
B
data to A bus
H
H
A
data to B bus
H
L
Isolation
L
H
B
data to A bus
A
data to B bus
H :
High level
L
:
Low level
HD74BC620A
2
Pin Arrangement
(Top view)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
V
CC
GBA
B1
B2
B3
B4
B5
B6
B7
B8
GAB
A1
A2
A3
A4
A5
A6
A7
A8
GND
Absolute Maximum Ratings
Item
Symbol
Rating
Unit
Supply voltage
V
CC
0.5 to +7.0
V
Input diode current
I
IK
30
mA
Input voltage
V
IN
0.5 to +7.5
V
Output voltage
V
OUT
0.5 to +7.5
V
Off state output voltage
V
OUT(off)
0.5 to +5.5
V
Storage temperature
Tstg
65 to +150
C
Note:
1. The absolute maximum ratings are values which must not individually be exceeded, and
furthermore, no two of which may be realized at the same time.
HD74BC620A
3
Recommended Operating Conditions
Item
Symbol
Min
Typ
Max
Unit
Supply voltage
V
CC
4.5
5.0
5.5
V
Input voltage
V
IN
0
--
V
CC
V
Ouput voltage
V
OUT
0
--
V
CC
V
Operating temperature
Topr
40
--
85
C
Input rise/fall time*
1
t
r
, t
f
0
--
8
ns/V
Note:
1. This item guarantees maximum limit when one input switches.
Waveform: Refer to test circuit of switching characteristics.
Logic Diagram
B1
B2
B3
B8
A1
GBA
A8
A3
A2
GAB
HD74BC620A
4
Electrical Characteristics (Ta = 40 to +85C)
Item
Symbol
V
CC
(V)
Min
Max
Unit
Test Conditions
Input voltage
V
IH
2.0
--
V
V
IL
--
0.8
V
Output voltage
V
OH
4.5
2.4
--
V
I
OH
= 3 mA
4.5
2.0
--
V
I
OH
= 15 mA
V
OL
4.5
--
0.5
V
I
OL
= 48 mA
4.5
--
0.55
V
I
OL
= 64 mA
Input diode voltage
V
IK
4.5
--
1.2
V
I
IN
= 18 mA
Input current
I
I
5.5
--
250
A
V
IN
= 0 V
5.5
--
1.0
A
GAB or
GBA
, V
IN
= 5.5 V
5.5
--
100
A
An or Bn, V
IN
= 5.5 V
5.5
--
100
A
GAB or
GBA
= 7 V
Output short circuit current*
1
I
OS
5.5
100
225
mA
V
IN
= 0 or 5.5 V
Off state output current
I
OZH
5.5
--
100
A
V
O
= 2.7 V
I
OZL
5.5
--
250
A
V
O
= 0.5 V
Supply current
I
CCL
5.5
--
29.5
mA
V
IN
= 0 or 5.5 V
All outputs is "L"
I
CCH
5.5
--
2.5
mA
V
IN
= 0 or 5.5 V
All outputs is "H"
I
CCZ
5.5
--
4.5
mA
V
IN
= 0 or 5.5 V
All outputs is "Z"
I
CCT
*
2
5.5
--
1.5
mA
V
IN
= 3.4 or 0.5 V
Notes: 1. Not more than one output should be shorted at a time and duration of the short circuit should not
exceed one second.
2. When input by the TTL level, it shows I
CC
increase at per one input pin.
HD74BC620A
5
Switching Characteristics (C
L
= 50 pF)
Ta = 25
C
V
CC
= 5.0 V
Ta = 40 to +85
C
V
CC
= 5.0 V
10%
Item
Symbol
Min
Max
Min
Max
Unit
Test Conditions
Propagation delay time
t
PLH
3.0
6.0
3.0
7.0
ns
An to Bn
t
PHL
3.0
6.0
3.0
7.0
t
PLH
3.0
6.0
3.0
7.0
ns
Bn to An
t
PHL
3.0
6.0
3.0
7.0
Output enable time
t
ZH
3.0
9.0
3.0
11.0
ns
GAB to Bn
t
ZL
3.0
9.0
3.0
11.0
t
ZH
3.0
9.0
3.0
11.0
ns
GBA
to An
t
ZL
3.0
9.0
3.0
11.0
Output disable time
t
HZ
3.0
8.0
3.0
10.0
ns
GAB to Bn
t
LZ
3.0
8.0
3.0
10.0
t
HZ
3.0
8.0
3.0
10.0
ns
GBA
to An
t
LZ
3.0
8.0
3.0
10.0
Input capacitance
C
IN
3.0 (Typ)
--
pF
V
IN
= V
CC
or GND
Output capacitance
C
I/O
15.0 (Typ)
--
pF
V
I/O
= V
CC
or GND
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