| 摘要 |
An LED indicator circuit has first and second input nodes, the first input node being electrically connected to the first terminal of a positive temperature coefficient resistor (PTC). The second terminal of the PTC is electrically connected to the cathode of a first diode, the anode of the first diode being electrically connected to the second input node. A series of diodes are electrically connected anode to cathode in parallel with said first diode. The anode of the first in the series of diodes is electrically connected to the second terminal of the PTC while the cathode of the last in the series of diodes is electrically connected to the second input node. Further, connected in parallel with the first diode and the series of diodes is an LED indicator having its anode electrically connected to the second terminal of the PTC and the cathode electrically connected to the second input node. The LED indicator circuit is capable of withstanding mis-wirings in which high voltages of greater than 50 volts DC can be applied to the circuit without damaging the circuit, while during normal operation, the LED will operate properly between 0 and 2.5 volts DC with negligible effect from the protection circuit. <IMAGE> |
