PA241 Datasheet, PDF (6/6 Pages) List of Unclassifed Manufacturers – High Voltage Power Operational Amplifiers

PA241
OPERATING
CONSIDERATIONS
inches is recommended. This may be adequate heatsinking
but the large number of variables involved suggest temperature
measurements be made on the top of the package. Do not
allow the temperature to exceed 85°C.
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+Vs _Z1
-IN
+Vs
Q1
Q2
+IN
-Vs
OUT
Z2
-Vs
FIGURE 1
OVERVOLTAGE PROTECTION
Although the PA241 can withstand differential input voltages
up to 16V, in some applications additional external protection
may be needed. Differential inputs exceeding 16V will be
clipped by the protection circuitry. However, if more than a few
milliamps of current is available from the overload source, the
protection circuitry could be destroyed. For differential sources
above 16V, adding series resistance limiting input current to
1mA will prevent damage. Alternatively, 1N4148 signal diodes
connected anti-parallel across the input pins is usually sufficient.
In more demanding applications where bias current is impor-
tant, diode connected JFETs such as 2N4416 will be required.
See Q1 and Q2 in Figure 1. In either case the differential input
voltage will be clamped to 0.7V. This is sufficient overdrive to
produce the maximum power bandwidth.
In the case of inverting circuits where the +IN pin is grounded,
the diodes mentioned above will also afford protection from
excessive common mode voltage. In the case of non-invert-
ing circuits, clamp diodes from each input to each supply will
provide protection. Note that these diodes will have substantial
reverse bias voltage under normal operation and diode leak-
age will produce errors.
Some applications will also need over-voltage protection
devices connected to the power supply rails. Unidirectional
zener diode transient suppressors are recommended. The
zeners clamp transients to voltages within the power supply
rating and also clamp power supply reversals to ground.
Whether the zeners are used or not the system power supply
should be evaluated for transient performance including power-
on overshoot and power-off polarity reversals as well as line
regulation. See Z1 and Z2 in Figure 1.
APPLICATION REFERENCES:
For additional technical information please refer to the fol-
lowing Application Notes:
AN1: General Operating Considerations
AN3: Bridge Circuit Drives
AN25: Driving Capacitive Loads
AN38: Loop Stability with Reactive Loads
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PA241U REV B AUGUST 2005 © 2005 Apex Microtechnology Corp.