Take the 2-minute tour ×
Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It's 100% free, no registration required.

I am wondering what the effects are of putting diodes in parallel or putting them in series. (like current capabilities, voltage capabilities etc.) Let's say I have a datasheet of a diode. What characteristics would change ? My estimation is that putting parallel would increase the current capabilities, but may have a negative effect in reverse leakage. I have no idea if I am right or how to test it, so any info on diodes in parallel or series would be great.

share|improve this question
add comment

2 Answers

up vote 2 down vote accepted

Connecting diodes in series (AK-AK --|<--|<--) will increase the forward voltage of the resultant diode.

Connecting diodes in series (AK-KA --|<-->|--) will cause an open circuit until peak inverse voltage (smallest diode) is applied on total resultant.

Connecting diodes in parallel (AK/AK --|<-- + --|<--) will increase the current carrying capacity of the diode.

Connecting diodes in parallel (AK/KA --|<-- + -->|--) will not get you a resultant diode conduction in both sides.

I hope my illustrations are understandable :-)

share|improve this answer
5  
I am affraid you cannot increase current capability so easily. At least some small resistors in series would be handy in that parallel combination of diodes. –  Al Kepp Jan 7 '13 at 6:16
add comment

Putting diodes in series will add the diode drops together. Reverse leakage (and capacitance) should reduce in this configuration.

In parallel, the drop will stay the same (reverse leakage and capacitance will add), but the current capability may not be much higher, due to the possibility of thermal runaway (since as a diode gets hotter it's Vf drops, then it draws more current relative to the rest, gets hotter still, and so on). You can avoid this somewhat by placing the diodes in thermal contact with each other, and/or using a small resistor in series with each.

share|improve this answer
6  
The same applies to diodes in series; you cannot rely on increasing the voltage rating unless you add a HIGH value resistance across each diode - rated to conduct say 10x the worst-case reverse leakage current across the volt/temperature range. Otherwise one diode leaks, and the other breaks down... –  Brian Drummond Jan 7 '13 at 11:45
    
@BrianDrummond - Yes, good point, you're right - the figures cannot be accurately predicted. –  Oli Glaser Jan 7 '13 at 13:09
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.