A short circuit protection is a current-limiting with foldback type. Foldback is desirable since the short circuit power dissipation of the series-pass transistor Q1 can be limited, preventing damage to it. The emitter of Q2 is connected to the output which effectively reverse biases transistor Q2. If the negative and positive output terminals are accidentally short circuited, the emitter of Q2 will be grounded. Current flowing through R2,R4< and R5 will force saturation, thereby limiting the current to almost zero. On the other hand, when the short circuit is removed, the output voltage will be back again since Q2 becomes reverse biased again.