LM139AW/883 National Semiconductor, LM139AW/883 Datasheet - Page 11

• Manufacturer Part Number: LM139AW/883
• Description: Comparator Quad ±15V/30V 14-Pin CPAK Rail
• Manufacturer: National Semiconductor

Specifications of LM139AW/883

• Package: 14CPAK
• Typical Response Time: 5(Max) us
• Typical Response Time Range: 5 to 20 us
• Typical Voltage Gain Range: 90 to 110 dB
• Output Type: Open Collector
• Number Of Channels Per Chip: 4
• Minimum Single Supply Voltage: 5 V
• Power Supply Type: Single|Dual

Driving CMOS
Application Hints
The LM139 series are high gain, wide bandwidth devices
which, like most comparators, can easily oscillate if the output
lead is inadvertently allowed to capacitively couple to the in-
puts via stray capacitance. This shows up only during the
output voltage transition intervals as the comparator changes
states. Power supply bypassing is not required to solve this
problem. Standard PC board layout is helpful as it reduces
stray input-output coupling. Reducing this input resistors to <
10 kΩ reduces the feedback signal levels and finally, adding
even a small amount (1 to 10 mV) of positive feedback (hys-
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teresis) causes such a rapid transition that oscillations due to
Driving TTL
stray feedback are not possible. Simply socketing the IC and
attaching resistors to the pins will cause input-output oscilla-
tions during the small transition intervals unless hysteresis is
used. If the input signal is a pulse waveform, with relatively
fast rise and fall times, hysteresis is not required.
All pins of any unused comparators should be tied to the neg-
ative supply.
The bias network of the LM139 series establishes a drain
current which is independent of the magnitude of the power
supply voltage over the range of from 2 V
to 30 V
.
DC
DC
It is usually unnecessary to use a bypass capacitor across the
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power supply line.
AND Gate
The differential input voltage may be larger than V
+
without
damaging the device. Protection should be provided to pre-
vent the input voltages from going negative more than −0.3
V
(at 25°C). An input clamp diode can be used as shown
DC
in the applications section.
The output of the LM139 series is the uncommitted collector
of a grounded-emitter NPN output transistor. Many collectors
can be tied together to provide an output OR'ing function. An
output pull-up resistor can be connected to any available
power supply voltage within the permitted supply voltage
range and there is no restriction on this voltage due to the
magnitude of the voltage which is applied to the V
+
terminal
of the LM139A package. The output can also be used as a
simple SPST switch to ground (when a pull-up resistor is not
used). The amount of current which the output device can sink
is limited by the drive available (which is independent of V
+
)
and the β of this device. When the maximum current limit is
reached (approximately 16 mA), the output transistor will
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come out of saturation and the output voltage will rise very
OR Gate
rapidly. The output saturation voltage is limited by the ap-
proximately 60Ω R
of the output transistor. The low offset
SAT
voltage of the output transistor (1 mV) allows the output to
clamp essentially to ground level for small load currents.
Typical Applications
(V
+
= 5.0 V
)
DC
Basic Comparator
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