clc431 National Semiconductor Corporation, clc431 Datasheet - Page 4

• Manufacturer Part Number: clc431
• Description: Dual Wideband Monolithic Op Amp With Disable
• Manufacturer: National Semiconductor Corporation

Introduction
The CLC431 and the CLC432 are dual wideband current-
feedback op amps that operate from single (+10V to
+33V) or dual (±5V to ±16.5) power supplies. The
CLC431 is equipped with a disable feature and is offered
in 14-pin DIP and SOIC packages. The CLC432 is
packaged in a standard 8-pin dual pinout and is offered
in an 8-pin DIP and SOIC. Evaluation boards are available
for each version of both devices. The evaluation boards
can assist in the device and/or application evaluation and
were used to generate the typical device performance
plots on the preceding pages.
Each of the CLC431/CLC432's dual channels provide
closely matched DC & AC electrical performance
characteristics making them ideal choices for wideband
signal processing. The CLC431, with its disable feature,
can easily be configured as a 2:1 mux or several can be
used to form a 10:1 mux without performance degradation.
The two closely-matched channels of the CLC432 can be
combined to form composite circuits for such applications
as filter blocks, integrators, transimpedance amplifiers
and differential line drivers and receivers.
Feedback Resistor Selection
The loop gain and frequency response for a current-
feedback operational amplifier is determined largely by
the feedback resistor (R
influence ac response. Since the package parasitics of
the CLC431 and the CLC432 are different, the optimum
frequency and phase responses are obtained with different
values of feedback resistor (for A
CLC432: R
http://www.national.com
f
=750 ). The Electrical Characteristics and
f
). Package parasitics also
V
=+2; CLC431: R
Application Discussion
f
=866 ,
4
Typical Performance plots are valid for both devices
under the specified conditions. Generally, lowering R
from its recommended value will peak the frequency
response and extend the bandwidth while increasing its
value will roll off the response. Reducing the value of R
too far below its recommended value will cause overshoot,
ringing and eventually oscillation. For more information
see Application Note OA-20 and OA-13.
In order to optimize the devices' frequency and phase
response for gains other than +2V/V it is recommended
to adjust the value of the feedback resistor. The two plots
found in the Typical Performance section entitled
"Recommended R
selecting the feedback-resistor value that optimizes
frequency and phase response over the CLC431/
CLC432's gain range. Both plots show the value of R
approaching a nonzero minimum at high non-inverting
gains, which is characteristic of current-feedback op
amps and yields best results. The linear portion of the
two R
placed on R
adequate input impedance for the inverting configuration.
It should be noted that for stable operation a non-
inverting gain of +1 requires an R
the CLC431 and the CLC432.
CLC431 Disable Feature
The CLC431 disable feature can be operated either
single-endedly or differentially thereby accommodating a
wide range of logic families. There are three pins asso-
ciated with the disable feature of each of the CLC431's
two amplifiers: DIS DIS and V
f
vs. Inverting-gain curves results from the limitation
g
(i.e. R
,
f
vs. Gain" provide the means of
g
50 ) in order to maintain an
RTTL
f
(please see pinout on
equal to 1k for both
f
f
f