Have a circuit where i can use Zener diodes, but cannot find high enough wattage rating. Is it OK to parallel 2 zeners and should I worry about puttinga small resistor on leads to balance them out or as long as I use same batch should be fine?
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Can you parallel Zener Diodes?
- Thread starter Crusher
- Start date
No, you can't.
Since the breakdown voltage will never be identical between the two zeners, one diode will always swamp out the other and conduct the most current, until it burns out. Then the other diode will start carrying the load until it burns out, too.
Adding a resistor in series will help distribute the current more evenly. But unfortunately it will also add a linear section to the curve and the reason you're using zeners is specifically because they are NOT linear. You'll be destroying their ability to sharply clamp voltage.
Find a bigger diode.
Since the breakdown voltage will never be identical between the two zeners, one diode will always swamp out the other and conduct the most current, until it burns out. Then the other diode will start carrying the load until it burns out, too.
Adding a resistor in series will help distribute the current more evenly. But unfortunately it will also add a linear section to the curve and the reason you're using zeners is specifically because they are NOT linear. You'll be destroying their ability to sharply clamp voltage.
Find a bigger diode.
Alrighty then. Thanks for the reply.Kinda thought so but was not sure. Had some 50 watt zeners, but need just a bit more. Something like a 75 or 100 watt. Might try zener with heavy duty pass transistor.