Diode question

[Holger Barske]

I am looking for a reliable rectifier vor 15V transformer secondary voltage. The load is going to take 20A of current.
I would like to use four MBR2045CT (datasheet), which is a double diode with common cathode. I would like to parallel both halves. Will this work without problems?
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Thanks, Holger

 

[ashok]

Parallel diodes

Hi Holger,
You need to be careful about using diodes in parallel. Unless they have the exact same characteristics they will not share the current equally. It would be safer to use higher current diodes . Check it out.
Cheers

 

[subwo1]

Hi. Even though it is true that due to the negative temperature coeffcient that diodes have they don't share current evenly, they in practice, can come pretty close if their temperatures are close and they are the same diodes, of course. I have done it often. Even if instead of getting a new ratiing of 40 amps you end up with 35 amps, that is still a big increase. The reason it increases is that they still suffer from an increased voltage drop with increasing current. Also, being in the same package will tend to greatly negate the temperature differences between the two diodes.