| 摘要 |
<p>A contact wetting circuit 100 is disclosed for supplying wetting current to sense the state of dry contacts of a switch SW1 setting for an electronic device 10. The contact wetting circuit includes an RC circuit 110 having a resistor R1 and a capacitor C1, and a controller 120 connected to a power supply 130 of the device. The controller supplies a first voltage to the RC circuit to produce a charging current having an average current and/or a peak current below the wetting current parameter of the dry contacts. The charging current is used to charge the capacitor C1 during the first time period. The controller stops the supply of the first voltage to the RC circuit after sufficient charging to allow the charged capacitor C1 to supply a second voltage, across the switch SW1, to produce a wetting current. Thereafter, the controller polls and senses the state of the switch SW1, and performs certain operations accordingly.</p> |
