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 150W at a gain of +2.
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 25W, 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:
Video Performance has also been measured with a 500W
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 500W 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 50W
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
50W loads.
TJMAX = TMAX + (qJA * n * PDMAX) [1]
where:
TMAX=Maximum Ambient Temperature
qJA=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:
Driving Cables and Capacitive Loads
PDMAX = (2 * VS * ISMAX) + (VS - VOUTMAX) *
(VOUTMAX/RL) [2]
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
where:
VS=Supply Voltage
ISMAX=Maximum Supply Current of 1 Amplifier
VOUTMAX=Max. Output Voltage of the Application
RL=Load Resistance
series resistor (usually between 5W and 50W) 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.
12
ELANTEC [ ELANTEC SEMICONDUCTOR ]
