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DM74ALS5245-1 Schematic ( PDF Datasheet ) - Fairchild Semiconductor

Teilenummer DM74ALS5245-1
Beschreibung Octal 3-STATE Transceiver
Hersteller Fairchild Semiconductor
Logo Fairchild Semiconductor Logo 




Gesamt 8 Seiten
DM74ALS5245-1 Datasheet, Funktion
March 1998
DM74ALS5245/74ALS5245-1
Octal 3-STATE Transceiver
General Description
This octal bus transceiver is designed for asynchronous
two-way communication between data buses. The inputs in-
clude hysteresis which provides improved noise rejection.
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 di-
rection control (DIR) input. The device can be disabled via
the enable input (G ) which causes the outputs to enter the
high impedance mode so the buses are effectively isolated.
The ALS5245-1 features the same performance as the
ALS5245 with the addition of increased current drive capa-
bility to meet the requirements of various bus architectures.
The recommended maximum IOL is increased to 48 mA.
Features
n Input Hysteresis
n Low output noise generation
n High input noise immunity
n Advanced oxide-isolated, ion implanted Schottky TTL
process
n Switching specification guaranteed over the full
temperature and VCC range
n PNP inputs to reduce input loading
n Maximum IOL is increased to 48 mA for ALS5245-1
Ordering Code:
Order Number Package Number
DM74ALS5245WM
M20B
DM74ALS5245SJ
M20D
DM74ALS5245N
N20A
DM74ALS5245-1WM
M20B
DM74ALS5245-1SJ
M20D
DM74ALS5245-1N
N20A
Package Description
20-Lead Small Outline Package – JEDEC (M)
20-Lead Small Outline Package – EIAJ (SJ)
20-Lead Molded Dual-in-Line Package (N)
20-Lead Small Outline Package – JEDEC (M)
20-Lead Small Outline Package – EIAJ (SJ)
20-Lead Molded Dual-in-Line Package (N)
Device also available in Tape and Reel. Specify by appending suffix letter “X” to the ordering code.
Connection Diagram
DS009175-1
© 1998 Fairchild Semiconductor Corporation DS009175
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DM74ALS5245-1 Datasheet, Funktion
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, 500.
2. Deskew the word generator so that no two channels
have greater than 150 ps skew between them. This re-
quires 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 cor-
rect voltage.
4. Set VCC 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 measurement.
6. Set the word generator input levels at 0V LOW and 3V
HIGH. Verify levels with a digital volt meter.
VOLP/VOLV and VOHP/VOHV:
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 50coaxial cable plugged into a standard
SMB type connector on the test fixture. Do not use an ac-
tive FET probe.
Measure VOLP and VOLV on the quiet output during the
HL transition. Measure VOHP and VOHV 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.
VILD and VIHD:
Monitor one of the switching outputs using a 50coaxial
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, VIL, until the
output begins to oscillate. Oscillation is defined as noise
on the output LOW level that exceeds VIL limits, or on
output HIGH levels that exceed VIH limits. The input LOW
voltage level at which oscillation occurs is defined as
VILD.
Next decrease the input HIGH voltage level on the word
generator, VIH until the output begins to oscillate. Oscilla-
tion is defined as noise on the output LOW level that ex-
ceeds VIL limits, or on output HIGH levels that exceed VIH
limits. The input HIGH voltage level at which oscillation
occurs is defined as VIHD.
Verify that the GND reference recorded on the oscillo-
scope has not drifted to ensure the accuracy and repeat-
ability of the measurements.
DS009175-2
FIGURE 1. Quiet Output Noise Voltage Waveforms
Note 8: VOHV and VOHP are measured with respect to VOH reference. VOLV
and VOLP are measured with respect to ground reference.
Note 9: Input pulses have the following characteristics: f = 1 MHz, tr = 3 ns,
tf = 3 ns, skew < 150 ps.
DS009175-3
FIGURE 2. Simultaneous Switching Test Circuit
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