| 摘要 |
A current limited linear regulator including a pass transistor (56) is provided with a shutdown circuit (64) comprised of a shutdown transistor (90), base resistor (92), and zener diode (98). When an excessive load is placed on the regulator and the current level limit is reached, the output voltage begins to drop and the voltage drop V2 across the pass transistor (56) increases. When the voltage drop V2 across the pass transistor (56) is equivalent to the sum of the zener voltage of the zener diode (98) and the emitter-base junction bias voltage of the shutdown transistor (90), the transistor (90) switches a current into bias resistor (62) that prevents the control circuit from regulating the output, causing the pass transistor to become highly resistive and shut off. The shutdown circuit holds this condition until the offending load is effectively removed. The zener diode is chosen according to the power rating of the pass transistor (56) and the predetermined current level limit.
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