LM101A National Semiconductor, LM101A Datasheet - Page 10

• Manufacturer Part Number: LM101A
• Description: Operational Amplifiers
• Manufacturer: National Semiconductor

www.national.com
Application Hints
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 resis-
tor. Low impedance sources do not cause a problem unless
their output voltage exceeds the supply voltage. However,
the supplies go to zero when they are turned off, so the iso-
lation 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-
Typical Applications
for
the
Standard Compensation and
Offset Balancing Circuit
integrated
(Note 9) (Continued)
circuit
(Note 9)
DS007752-29
never
become
Power Bandwidth: 15 kHz
Slew Rate: 1V/µs
10
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 k , 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.
Fast Voltage Follower
+
and V
DS007752-31
−
will always cause a