Transistors Q1 and Q2 form a voltage clamp network.This clamp performs a current-limiting function on the overload current to U1 at 10 mA during ohms and temperature overloads.

• Q1和Q2实现电压钳断网络，这个钳断会在欧姆或是温度过载时使得进入U1的电流在10毫安。