| 摘要 |
<p>The protection circuit has two components - a zener diode and an element having a positive temperature coefficient of resistance. The zener diode has voltage - current characteristics such that beyond a certain point, the voltage across its terminals remains stable. The two components are connected in series across the variable supply voltage, and are in intimate thermal contact. The load is connected across the zener diode terminals. The zener diode may alternatively be a varistor (VDR). This or the diode is bonded directly on to the PTC resistor or thermistor. Silicone grease may ensure a good thermal contact between the two components.</p> |
