CLC5612IM datasheet(16/18 Pages) NSC

16 / 18 page

Application Division (Continued)

Application Circuits

Single Supply Cable Driver

Figure 14 below shows the CLC5612 driving 10m of 75

Ω

coaxial cable. The CLC5612 is set for a gain of +2V/V to

compensate for the divide-by-two voltage drop at V

o. The

response after 10m of cable is illustrated in

Figure 15.

Differential Line Driver with Load

Impedance Conversion

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 CLC5612’s output capabilities.

The single-ended input signal is converted to a differential

signal by the CLC5612. 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 CLC5612 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 CLC5612’s output drive capability

as follows:

meq

max

+= ⋅

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 CLC5612 also affects the match. With an ideal

transformer we obtain:

Return Loss

20 log

,dB

o 5612

=− ⋅

⋅

()

() ω

where Z

o(5612)(jω) is the output impedance of the CLC5612

and |Z

o(5612)(jω)| <<Rm

The load voltage and current will fall in the ranges:

Vn V

≤⋅

≤

max

The CLC5612’s high output drive current an low distortion

make it a good choice for this application.

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

CLC5612

NOTE: Channel 2 not shown

DS015001-53

FIGURE 14. Single Supply Cable Driver

20ns/div

Vin = 10MHz, 0.5Vpp

DS015001-54

FIGURE 15. Response After 10m of Cable

Rt2

Vin

Rm/2

UTP

Req

1:n

Vd/2

Ω

CLC5612

-Vd/2

Note: Supplies and bypassing not shown.

DS015001-55

FIGURE 16. Differential Line Driver with Load

Impedance Conversionn

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