clc5632 National Semiconductor Corporation, clc5632 Datasheet - Page 16

• Manufacturer Part Number: clc5632
• Description: Dual, High Output, Programmable Gain Buffer
• Manufacturer: National Semiconductor Corporation

www.national.com
Application Division
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.
V
NOTE: Channel 2 not shown
75
o
Coaxial Cable
FIGURE 15. Response After 10m of Cable
10m of 75
FIGURE 14. Single Supply Cable Driver
V
V
in
in
= 10MHz, 0.5V
0.1 F
75
+5V
5k
5k
0.1 F
0.1 F
pp
20ns/div
2
3
1
4
(Continued)
1k
CLC5632
1k
+
1k
-
-
+
1k
8
7
6
5
+5V
DS015003-53
DS015003-54
6.8 F
0.1 F
+
16
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
V
Output Current.
Match the line’s characteristic impedance:
Select the transformer so that it loads the line with a value
very near Z
of the CLC5632 also affects the match. With an ideal trans-
former we obtain:
where Z
and |Z
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.
V
max
in
V
FIGURE 16. Differential Line Driver with Load
is the output Voltage Range, and I
R
d/2
O
t
(5632)(j )|
O
eq
(5632)(j ) is the output impedance of the CLC5632
is the transformed value of the load impedance,
3
1
2
4
O
over frequency range. The output impedance
1k
CLC5632
1k
Impedance Conversion
1k
-
+
+
-
<<
1k
R
m
8
7
6
5
.
R
R
R
-V
R
m/2
m/2
t2
eq
d/2
R
R
n
1:n
L
m
Note: Supplies and bypassing not shown.
max
R
Z
R
R
o
eq
is the maximum
eq
L
UTP
Z
o
DS015003-55
I
o
R
L