When choosing a value for R6, ensure that Q2's base-emittervoltage is less than approximately 0.5V at the maximum permissible value of the load current.
选择R6的阻值时要确保在负载电流的最高允许值的条件下，Q2的基极-发射极电压大约低于0.5V。
2
Consequently, no load current flows through R6 because Q2, whose base-emittervoltage is now 0v, has turned off.
由于Q2的基极-发射极的电压为0 V而截止，因此没有负载电流流过r6。
3
In the event of an overload when ILOAD exceeds its maximum permissible value, the increase in voltage across R6 results in sufficient base-emittervoltage to turn on Q2.