| 摘要 |
<p>TELEPHONE SUBSCRIBER LINE BATTERY FEED RESISTOR ARRANGEMENTS Battery feed resistors are constituted by thick film resistors on a substrate, electrically in series with switching type positive temperature coefficient (PTC) resistors which are closely thermally coupled to the thick film resistors by being mounted on the substrate behind the thick film resistors or on insulating layers over the thick film resistors. Precise battery feed resistances and matching of pairs of battery feed resistors are achieved by trimming the thick film resistors. The PTC resistors prevent excessively high temperatures being reached in the event that external high voltages are applied to a telephone subscriber line to which the battery feed resistors are connected.</p> |
