LM101AW/883 National Semiconductor Corporation, LM101AW/883 Datasheet - Page 17

• Manufacturer Part Number: LM101AW/883
• Description: Lm101aqml Operational Amplifiers
• Manufacturer: National Semiconductor Corporation

Although the LM101A is designed for trouble free operation,
experience has indicated that it is wise to observe certain
precautions given below to protect the devices from abnor-
mal operating conditions. It might be pointed out that the
advice given here is applicable to practically any IC op amp,
although the exact reason why may differ with different de-
vices.
When driving either input from a low-impedance source, a
limiting resistor should be placed in series with the input lead
to limit the peak instantaneous output current of the source
to something less than 100 mA. This is especially important
when the inputs go outside a piece of equipment where they
could accidentally be connected to high voltage sources.
Large capacitors on the input (greater than 0.1 µF) should be
treated as a low source impedance and isolated with a
resistor. Low impedance sources do not cause a problem
unless their output voltage exceeds the supply voltage. How-
ever, the supplies go to zero when they are turned off, so the
isolation is usually needed.
The output circuitry is protected against damage from shorts
to ground. However, when the amplifier output is connected
to a test point, it should be isolated by a limiting resistor, as
test points frequently get shorted to bad places. Further,
when the amplifer drives a load external to the equipment, it
is also advisable to use some sort of limiting resistance to
preclude mishaps.
Precautions should be taken to insure that the power sup-
plies
reversed — even under transient conditions. With reverse
voltages greater than 1V, the IC will conduct excessive cur-
rent, fusing internal aluminum interconnects. If there is a
possibility of this happening, clamp diodes with a high peak
current rating should be installed on the supply lines. Rever-
sal of the voltage between V
problem, although reversals with respect to ground may also
give difficulties in many circuits.
The minimum values given for the frequency compensation
capacitor are stable only for source resistances less than
10 kΩ, stray capacitances on the summing junction less than
5 pF and capacitive loads smaller than 100 pF. If any of
these conditions are not met, it becomes necessary to over-
compensate the amplifier with a larger compensation capaci-
tor. Alternately, lead capacitors can be used in the feedback
network to negate the effect of stray capacitance and large
feedback resistors or an RC network can be added to isolate
capacitive loads.
Although the LM101A is relatively unaffected by supply by-
passing, this cannot be ignored altogether. Generally it is
necessary to bypass the supplies to ground at least once on
every circuit card, and more bypass points may be required
if more than five amplifiers are used. When feed-forward
compensation is employed, however, it is advisable to by-
pass the supply leads of each amplifier with low inductance
capacitors because of the higher frequencies involved.
for
the
integrated
+
and V
circuit
−
will always cause a
never
become
17
Typical Applications
Power Bandwidth: 15 kHz
Slew Rate: 1V/µs
Power Bandwidth: 250 kHz
Small Signal Bandwiidth: 3.5 MHz
Slew Rate: 10V/µs
Standard Compensation and
Fast Summing Amplifier
Offset Balancing Circuit
Fast Voltage Follower
(Note 11)
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