parallel diodes?

[net-david]

Sorry for the basic electronics 101 question, but I really did search and even googled for this...

What happens when you parallel identical diodes, specifically in a power supply rectifier? I would assume double the current capacity, but are there any other advantages and/or disadvantages?

Thanks for your help,
David

 

[JOE DIRT®]

you can do that but with power resistors on each anode...its a really inefficient way to do something when diodes are so cheap


DIRT®

 

[peranders]

You don't do this! Why? They will share current and when one of the diodes gets hotter, the other one gets cooler, and the first one gets even hotter because of this. The whole thing ends up with only one diode taking most of the current.

In a non-critical situation you can use a double diode (parallel connected) in a TO220 package or similar but normally you should use a diode which fits the application. Inserting resistors is possible but isn't it cheaper/easier to just get a larger diode?

 

[net-david]

Okay! I won't do it!!

I was just wondering if there was some technical or sonic benefit of parallel diodes, I understand that there isn't.

I have ISL9R860P2 and ISL9R460P2, I was contemplating using two of the 4 amp instead of one 8 amp.

Thanks again for the help,
David

 

[jackinnj]

You don't do this! Why? They will share current and when one of the diodes gets hotter, the other one gets cooler, and the first one gets even hotter because of this. The whole thing ends up with only one diode taking most of the current.

In a non-critical situation you can use a double diode (parallel connected) in a TO220 package or similar but normally you should use a diode which fits the application. Inserting resistors is possible but isn't it cheaper/easier to just get a larger diode?

I think that ON-Semi has no problems using some of their double-diodes in this fashion, something like the MBR20100CT.