Datasheet

L78Sxx, L78SxxC Typical performance
Doc ID 2148 Rev 7 31/39
1. Application with high capacitance loads and an output voltage greater than 6 volts need an external diode
(see
Figure 30 on page 28 ) 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 37. Protection against input short-circuit with high capacitance loads