CLC5632 datasheet(16/19 Pages) NSC

16 / 19 page

Application Division (Continued)

Differential Line Driver with Load Impedance Conver-

sion

The circuit shown in the Typical Application schematic on

the front page and in

Figure 16, operates as a differential line

driver. The transformer converts the load impedance to a

value that best matches the CLC5632’s output capabilities.

The single-ended input signal is converted to a differential

signal by the CLC5632. The line’s characteristic impedance

is matched at both the input and the output. The schematic

shows Unshielded Twisted Pair for the transmission line;

other types of lines can also be driven.

Set up the CLC5632 as a difference amplifier:

•

Set the Channel 1 amplifier to a gain of +1V/V

•

Set the Channel 2 amplifier to a gain of −1V/V

Make the best use of the CLC5632’s output drive capability

as follows:

where R

eq is the transformed value of the load impedance,

max is the output Voltage Range, and Imax is the maximum

Output Current.

Match the line’s characteristic impedance:

meq

Select the transformer so that it loads the line with a value

very near Z

O over frequency range. The output impedance

of the CLC5632 also affects the match. With an ideal trans-

former we obtain:

where Z

O(5632)(jω) is the output impedance of the CLC5632

and |Z

O(5632)(jω)|<<Rm.

The load voltage and current will fall in the ranges:

The CLC5632’s high output drive current and low distortion

make it a good choice for this application.

Differential Input/Differential Output Amplifier

below illustrates a differential input/differential output con-

figuration. The bypass capacitors are the only external com-

ponents required.

Ω

0.1

µF

6.8

µF

Vin

Ω

+5V

0.1

µF 0.1µF

10m of 75

Ω

Coaxial Cable

Ω

0.1

µF

Ω

CLC5632

NOTE: Channel 2 not shown

DS015003-53

FIGURE 14. Single Supply Cable Driver

20ns/div

Vin = 10MHz, 0.5Vpp

DS015003-54

FIGURE 15. Response After 10m of Cable

Rt2

Vin

Rm/2

UTP

Req

1:n

Vd/2

Ω

CLC5632

-Vd/2

Note: Supplies and bypassing not shown.

DS015003-55

FIGURE 16. Differential Line Driver with Load

Impedance Conversion

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