http://www.national.com

10

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Components not used:

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The evaluation boards are designed to accommodate

dual supplies. The boards can be modified to provide

single supply operation.

For best performance; 1) do

not connect the unused supply, 2) ground the unused

supply pin.

SPICE Models

SPICE models provide a means to evaluate amplifier

designs. Free SPICE models are available for National’s

monolithic amplifiers that:

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Support Berkeley SPICE 2G and its many derivatives

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Reproduce typical DC, AC, Transient, and Noise

performance

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Support room temperature simulations

The

readme file that accompanies the diskette lists

released models, and provides a list of modeled parame-

ters.

The application note OA-18, Simulation SPICE

Models for National’s Op Amps, contains schematics and

a reproduction of the readme file.

Single Supply Cable Driver

The typical application shown on the front page shows

the CLC450 driving 10m of 75

Ω coaxial cable. The

CLC450 is set for a gain of +2V/V to compensate for the

Single Supply Lowpass Filter

Figures 9 and 10 illustrate a lowpass filter and design

equations. The circuit operates from a single supply of

+5V. The voltage divider biases the non-inverting input to

2.5V. And the input is AC coupled to prevent the need for

level shifting the input signal at the source.

Use the

on the desired Q and corner frequency.

Figure 9: Lowpass Filter Topology

Figure 10: Design Equations

This example illustrates a lowpass filter with Q = 0.707

sen to achieve a maximally flat, Butterworth response.

Figure 11 indicates the filter response.

Figure 11: Lowpass Response

Twisted Pair Driver

The high output current and low distortion, of the

CLC450, make it well suited for driving transformers.

Figure 12 illustrates a typical twisted pair driver utilizing

the CLC450 and a transformer. The transformer

provides the signal and its inversion for the twisted pair.

Figure 12: Twisted Pair Driver

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Application Circuits

+

-

1k

Ω

0.1

µF

5k

Ω

4

7

6

0.1

µF

0.1

µF

5k

Ω

CLC450

3

2

+5V

0.1

µF

100

Ω

1.698k

Ω

158

Ω

158

Ω

100pF

Gain

K

1

R

R

Corner frequency

1

RR C C

Q

1

RC

RC

RC

RC

(1 K)

RC

RC

For R

R

R and C

C

C

1

RC

Q

1

(3 K)

f

g

c

12 1 2

22

11

12

21

11

22

12

1

2

c

== +

==

=

++

−

==

=

=

=

=

−

ω

ω

Frequency (Hz)

-21

-15

-9

-3

3

1M

10M

100M

+

-

+

-

UTP

I:n

CLC450

3

2

6

A1

R

R

v

f

g

=+

V

n

4

AV

v in

=

V

-n

4

AV

v in

=

V

1n

2

AV

ov in

=