EL5293, EL5293A
capable of driving 50 loads to both rails, making it 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 EL5293 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 output to eliminate
most peaking. The gain resistor (RG) can 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 feedback
resistor (RF) to reduce the peaking.
Current Limiting
The EL5293 has 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 EL5293, it is
possible to exceed the +125°C Absolute Maximum junction
temperature under certain very high load current conditions.
Generally speaking when RL falls below about 25, it is
important to calculate 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 EL5293 to remain in the safe operating area.
These parameters are calculated as follows:
TJMAX = TMAX + JA n PDMAX
(EQ. 1)
where:
TMAX = Maximum ambient temperature
JA = Thermal resistance of the package
n = Number of amplifiers in the package
PDMAX = Maximum power dissipation of each amplifier in
the package
PDMAX for each amplifier can be calculated as follows:
PDMAX = 2 VS ISMAX + VS - VOUTMAX -V----O----U--R--T---L-M-----A----X--
(EQ. 2)
where:
VS = Supply voltage
ISMAX = Maximum supply current of 1A
VOUTMAX = Maximum output voltage (required)
RL = Load resistance
FN7193 Rev 3.00
July 26, 2007
Page 14 of 16