8

Supply Voltage Range and Single-Supply

Operation

The EL5106 and EL5306 have been designed to operate

with supply voltages having a span of greater than or equal

to 5V and less than 11V. In practical terms, this means that

the EL5106 and EL5306 will operate on dual supplies

ranging from ±2.5V to ±5V. With single-supply, the EL5106

and EL5306 will operate from 5V to 10V.

As supply voltages continue to decrease, it becomes

necessary to provide input and output voltage ranges that

can get as close as possible to the supply voltages. The

EL5106 and EL5306 have an input range which extends to

within 2V of either supply. So, for example, on ±5V supplies,

the EL5106 and EL5306 have an input range which spans

±3V. The output range is also quite large, extending to within

1V of the supply rail. On a ±5V supply, the output is therefore

capable of swinging from -4V to +4V. Single-supply output

range is larger because of the increased negative swing due

to the external pull-down resistor to ground. Figure 16 shows

an AC-coupled, gain of +2, +5V single supply circuit

configuration.

Video Performance

For good video performance, an amplifier is required to

maintain the same output impedance and the same

frequency response as DC levels are changed at the output.

This is especially difficult when driving a standard video load

of 150

Ω, because of the change in output current with DC

level. Previously, good differential gain could only be

achieved by running high idle currents through the output

transistors (to reduce variations in output impedance).

Special circuitries have been incorporated in the EL5106 and

EL5306 to reduce the variation of output impedance with

current output. This results in dG and dP specifications of

0.02% and 0.04°, while driving 150

Ω at a gain of 2.

Output Drive Capability

In spite of its low 1.5mA of supply current per amplifier, the

EL5106 and EL5306 are capable of providing a maximum of

±125mA of output current.

Driving Cables and Capacitive Loads

When used as a cable driver, double termination is always

recommended for reflection-free performance. For those

applications, the back-termination series resistor will

decouple the EL5106 and EL5306 from the cable and allow

extensive capacitive drive. However, other applications may

have high capacitive loads without a back-termination

resistor. In these applications, a small series resistor (usually

between 5

Ω and 50Ω) can be placed in series with the

output to eliminate most peaking.

-

+

325

Ω

325

Ω

IN-

IN+

-

+

325

Ω

325

Ω

IN-

IN+

FIGURE 17.

-

+

325

Ω

325

Ω

+5

0.1µF

1K

1K

0.1µF

+5

EL5106, EL5306