EL5166, EL5167

FN7365 Rev 6.00

Page 11 of 16

September 14, 2010

supplies, the EL5166 and EL5167 have an input range

which spans ±3.2V. The output range of the EL5166 and

EL5167 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.

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

 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.) These currents were typically comparable to

the entire 8.5mA supply current of each EL5166 and

EL5167 amplifier. Special circuitry has been incorporated in

the EL5166 and EL5167 to reduce the variation of output

impedance with the current output. This results in dG and

dP specifications of 0.01% and 0.03°, while driving 150

 at

a gain of 2.

Output Drive Capability

In spite of their low 8.5mA of supply current, the EL5166 and

EL5167 are capable of providing a minimum of ±110mA of

output current. With so much output drive, the EL5166 and

EL5167 are capable of driving 50

 loads to both rails,

making them an excellent choice for driving isolation

transformers in telecommunications applications.

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 EL5166 and EL5167 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

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

then be chosen to make up for any gain loss which may be

created by this additional resistor at the output. In many

cases it is also possible to simply increase the value of the

Current Limiting

The EL5166 and EL5167 have no internal current-limiting

circuitry. If the output is shorted, it is possible to exceed the

Absolute Maximum Rating for output current or power

dissipation, potentially resulting in the destruction of the

device.

Power Dissipation

With the high output drive capability of the EL5166 and

EL5167, it is possible to exceed the +125°C Absolute

Maximum junction temperature under certain very high load

about 25

, it is important to calculate the maximum junction

power supply voltages, load conditions, or package type

need to be modified for the EL5166 and EL5167 to remain in

the safe operating area. These parameters are calculated as

follows:

where:

n = Number of amplifiers in the package

the package

where:







+

=

(EQ. 1)

2





----------------------------



–

+





=

(EQ. 2)