DM74ALS5245 Octal 3-STATE Transceiver
October 1986
Revised February 2000
DM74ALS5245
Octal 3-STATE Transceiver
General Description
This octal bus transceiver is designed for asynchronous
two-way communication between data buses. The inputs
include hysteresis which provides improved noise rejec-
tion. Data is transmitted either from the A bus to the B bus
or from the B bus to the A bus depending on the logic level
of the direction control (DIR) input. The device can be dis-
abled via the enable input (G) which causes the outputs to
enter the high impedance mode so the buses are effec-
tively isolated.
Features
s
Input Hysteresis
s
Low output noise generation
s
High input noise immunity
s
Advanced oxide-isolated, ion implanted Schottky TTL
process
s
Switching specification guaranteed over the full temper-
ature and V
CC
range
s
PNP inputs to reduce input loading
Ordering Code:
Order Number
DM74ALS5245WM
DM74ALS5245SJ
DM74ALS5245N
Package Number
M20B
M20D
N20A
Package Description
20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
20-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
20-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.
Connection Diagram
Function Table
Control Inputs
Operation
G
L
L
H
L
=
LOW Logic Level
DIR
L
H
X
H
=
HIGH Logic Level
B Data to A Bus
A Data to B Bus
High Impedance
X
=
Don't Care (Either LOW or HIGH Logic Level)
© 2000 Fairchild Semiconductor Corporation
DS009175
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DM74ALS5245
Absolute Maximum Ratings
(Note 1)
Supply Voltage
Input Voltage
Control Inputs
I/O Ports
Operating Free-Air Temperature Range
Storage Temperature Range
Typical
θ
JA
N Package
M Package
56.0°C/W
74.0°C/W
7V
5.5V
0°C to
+70°C
−65°C
to
+150°C
Note 1:
The “Absolute Maximum Ratings” are those values beyond which
the safety of the device cannot be guaranteed. The device should not be
operated at these limits. The parametric values defined in the Electrical
Characteristic tables are not guaranteed at the absolute maximum ratings.
The “Recommended Operating Conditions” table will define the conditions
for actual device operation.
7V
Recommended Operating Conditions
Symbol
V
CC
V
IH
V
IL
I
OH
I
OL
T
A
Supply Voltage
HIGH Level Input Voltage
LOW Level Input Voltage
HIGH Level Output Current
LOW Level Output Current
Free Air Operating Temperature Range
0
Parameter
Min
4.5
2
0.8
−15
24
70
Max
5.5
Units
V
V
V
mA
mA
°C
Electrical Characteristics
over recommended free air temperature range. All typical values are measured at V
CC
=
5V, T
A
=
25°C.
Symbol
V
IK
H
YS
V
OH
Parameter
Input Clamp Voltage
Hysteresis (V
T+
−
V
T−
)
HIGH Level
Output Voltage
V
OL
I
I
I
IH
I
IL
I
O
I
CC
LOW Level
Output Voltage
Input Current at
Maximum Input Voltage
HIGH Level Input Current
LOW Level Input Current
Output Drive Current
Supply Current
V
CC
=
Max, V
I
=
2.7V
V
CC
=
Max, V
I
=
0.4V
V
CC
=
Max, V
O
=
2.25V
V
CC
=
Max
Outputs HIGH
Outputs LOW
Outputs Disabled
V
OLP
V
OLV
V
IHD
V
ILD
Quiet Output Maximum
Dynamic V
OL
Quiet Output Minimum
Dynamic V
OL
Minimum High Level
Dynamic Input Voltage
Maximum Low Level
Dynamic Input Voltage
Note 2:
Plastic DIP package.
Note 3:
n
=
number of device outputs; n−1 outputs switching, each driven 0V to 3V one output @ GND.
Note 4:
n
=
number of device outputs; n outputs switching, n−1 inputs switching 0V to 3V. Input under test switching 3V to threshold (V
ILD
); 0V to threshold
(V
IHD
); f
=
1 MHz.
Test Conditions
V
CC
=
Min, I
I
= −18
mA
V
CC
=
Min
V
CC
=
4.5V to 5.5V
V
CC
=
Min
V
CC
=
Min
V
CC
=
Max
I
OH
= −0.4
mA
I
OH
= −3
mA
I
OH
=
Max
I
OL
=
12 mA
I
OL
=
24 mA
I/O Ports, V
I
=
5.5V
Control Inputs, V
I
=
7V
Min
Typ
Max
−1.5
Units
V
V
V
0.2
V
CC
−
2
2.4
2
0.32
3.2
0.25
0.35
0.4
0.5
100
100
20
−100
V
µA
µA
µA
mA
mA
−30
30
36
38
0.5
−0.2
1.6
1.0
−112
45
55
58
V
CC
=
5.0V, T
A
=
25°C
(Figures 1, 2; (Note 2)(Note 3))
V
CC
=
5.0V, T
A
=
25°C
(Figures 1, 2; (Note 2)(Note 3))
V
CC
=
5.0V, T
A
=
25°C
(Note 2)(Note 4)
V
CC
=
5.0V, T
A
=
25°C
(Note 2)(Note 4)
V
V
V
V
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DM74ALS5245
ALS Noise Characteristics
The setup of a noise characteristics measurement is critical
to the accuracy and repeatability of the tests. The following
is a brief description of the setup used to measure the
noise characteristics of ALS.
Equipment:
Word Generator
Printed Circuit Board Test Fixture
Dual Trace Oscilloscope
Procedure:
1. Verify Test Fixture Loading: Standard Load 50 pF,
500Ω.
2. Deskew the word generator so that no two channels
have greater than 150 ps skew between them. This
requires that the oscilloscope be deskewed first. Swap
out the channels that have more than 150 ps of skew
until all channels being used are within 150 ps. It is
important to deskew the word generator channels
before testing. This will ensure that the outputs switch
simultaneously.
3. Terminate all inputs and outputs to ensure proper load-
ing of the outputs and that the input levels are at the
correct voltage.
4. Set V
CC
to 5.0V.
5. Set the word generator to toggle all but one output at a
frequency of 1 MHz. Greater frequencies will increase
DUT heating and affect the results of the measure-
ment.
6. Set the word generator input levels at 0V LOW and 3V
HIGH. Verify levels with a digital volt meter.
V
OLP
/V
OLV
and V
OHP
/V
OHV
:
• Determine the quiet output pin that demonstrates the
greatest noise levels. The worst case pin will usually be
the furthest from the ground pin. Monitor the output volt-
ages using a 50Ω coaxial cable plugged into a standard
SMB type connector on the test fixture. Do not use an
active FET probe.
• Measure V
OLP
and V
OLV
on the quiet output during the
HL transition. Measure V
OHP
and V
OHV
on the quiet out-
put during the LH transition.
• Verify that the GND reference recorded on the oscillo-
scope has not drifted to ensure the accuracy and repeat-
ability of the measurements.
V
ILD
and V
IHD
:
• Monitor one of the switching outputs using a 50Ω coaxial
cable plugged into a standard SMB type connector on
the test fixture. Do not use an active FET probe.
• First increase the input LOW voltage level, V
IL
, until the
output begins to oscillate. Oscillation is defined as noise
on the output LOW level that exceeds V
IL
limits, or on
output HIGH levels that exceed V
IH
limits. The input
LOW voltage level at which oscillation occurs is defined
as V
ILD
.
• Next decrease the input HIGH voltage level on the word
generator, V
IH
until the output begins to oscillate. Oscil-
lation is defined as noise on the output LOW level that
exceeds V
IL
limits, or on output HIGH levels that exceed
V
IH
limits. The input HIGH voltage level at which oscilla-
tion occurs is defined as V
IHD
.
• Verify that the GND reference recorded on the oscillo-
scope has not drifted to ensure the accuracy and repeat-
ability of the measurements.
FIGURE 1. Quiet Output Noise Voltage Waveforms
Note 5:
V
OHV
and V
OHP
are measured with respect to V
OH
reference. V
OLV
and V
OLP
are measured with respect to ground reference.
Note 6:
Input pulses have the following characteristics: f
=
1 MHz, t
r
=
3 ns,
t
f
=
3 ns, skew
<
150 ps.
FIGURE 2. Simultaneous Switching Test Circuit
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