L7800 series

Typical performance

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1.

Application with high capacitance loads and an output voltage greater than 6 volts need an external diode

(see fig. 32) to protect the device against input short circuit. In this case the input voltage falls rapidly while

the output voltage decrease slowly. The capacitance discharges by means of the Base-Emitter junction of

the series pass transistor in the regulator. If the energy is sufficiently high, the transistor may be destroyed.

The external diode by-passes the current from the IC to ground.

Figure 36.

Protection against input short-circuit with high capacitance loads