| 摘要 |
A passive leakage management circuit 46 is connected across the output of a solid state power controller (SSPC) 48. Circuit 46 includes a voltage level detector circuit 58 comprising FET 66 and resistors 62 & R64, and a current sink circuit 60 comprising transistor 84 and resistor 92. When SSPC 48 is closed, 270V dc appears on supply line 52 and, via resistors 62 & R64, turns on FET 66, allowing a first current through resistor 80 to pass to ground, reducing the potential at node 94 and holding transistor 84 off. When SSPC 48 is opened, leakage current through the switch may lead to a lower voltage such as 25V on supply line 52. FET 66 then turns off. This allows the potential at node 94 to rise, turning on current sink transistor 84 and allowing a second current to flow from supply line 52 through transistor 84 and leakage resistor 92. It is disclosed that R92 may be a zener diode. The circuit responds autonomously to the voltage at the output of the solid state switch 48. A separate control input is not required. |
