EL2186CS datasheet(12/19 Pages) ELANTEC

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EL2186C, EL2286C

250MHz/3mA Current Mode Feedback Amp w/Disable

output. This results in dG and dP specifications of 0.05%

and 0.05° while driving 150

Ω at a gain of +2.

Video Performance has also been measured with a 500

Ω

load at a gain of +1. Under these conditions, the

EL2186C/EL2286C have dG and dP specifications of

0.01% and 0.01° respectively while driving 500

Ω at AV

= +1.

Output Drive Capability

In spite of its low 3mA of supply current, the EL2186C

is capable of providing a minimum of ±80mA of output

current. Similarly, each amplifier of the EL2286C is

capable of providing a minimum of ±50mA. These out-

put drive levels are unprecedented in amplifiers running

at these supply currents. With a minimum ±80mA of

output drive, the EL2186C is capable of driving 50

Ω

loads to ±4V, making it an excellent choice for driving

isolation transformers in telecommunications applica-

tions. Similarly, the ±50mA minimum output drive of

each EL2286C amplifier allows swings of ±2.5V into

Ω loads.

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 resis-

tor will decouple the EL2186C/EL2286C 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 peak-

ing. The gain resistor (RG) can then be chosen to make

up for any gain loss which may be created by this addi-

tional resistor at the output. In many cases it is also

possible to simply increase the value of the feedback

resistor (RF) to reduce the peaking.

Current Limiting

The EL2186C/EL2286C have no internal current-limit-

ing circuitry. If any output is shorted, it is possible to

exceed the Absolute Maximum Ratings for output cur-

rent or power dissipation, potentially resulting in the

destruction of the device.

Power Dissipation

With the high output drive capability of the

EL2186C/EL2286C, it is possible to exceed the 150°C

Absolute Maximum junction temperature under certain

very high load current conditions. Generally speaking,

when RL falls below about 25Ω, it is important to calcu-

late the maximum junction temperature (TJmax) for the

application to determine if power-supply voltages, load

conditions, or package type need to be modified for the

EL2186C/EL2286C to remain in the safe operating area.

These parameters are calculated as follows:

TJMAX = TMAX + (θJA * n * PDMAX) [1]

where:

TMAX=Maximum Ambient Temperature

θJA=Thermal Resistance of the Package

n=Number of Amplifiers in the Package

PDMAX=Maximum Power Dissipation of Each Ampli-

fier in the Package.

PDMAX for each amplifier can be calculated as follows:

PDMAX = (2 * VS * ISMAX) + (VS - VOUTMAX) *

(VOUTMAX/RL) [2]

where:

VS=Supply Voltage

ISMAX=Maximum Supply Current of 1 Amplifier

VOUTMAX=Max. Output Voltage of the Application

RL=Load Resistance

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