EL5293CSZ datasheet(14/16 Pages) RENESAS

14 / 16 page

EL5293, EL5293A

FN7193 Rev 3.00

Page 14 of 16

July 26, 2007

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

) 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:

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:

where:

VS = Supply voltage

ISMAX = Maximum supply current of 1A

VOUTMAX = Maximum output voltage (required)

RL = Load resistance

TJMAX

TMAX JA nPDMAX





(EQ. 1)

PDMAX



VS ISMAX



- VOUTMAX

VOUTMAX

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



(EQ. 2)

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