# Parasitic capacitance of a bridge rectifier diode

Discussion in 'General Electronics Chat' started by uwed, Jun 19, 2015.

1. ### uwed Thread Starter Member

Mar 16, 2015
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17
I need to know a good estimate for the parasitic capacitance of a bridge rectifier diode (50/60Hz) roughly in the parameter range 1.2V and 10A. I can't find anything in datasheets. I would like to know if this capacitance is in the range of 10pF or 100pF or 1nF or even higher.

2. ### #12 Expert

Nov 30, 2010
17,887
9,286
datasheet, page 1
datasheet, page 2

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• ###### Shot8A45V.pdf
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3. ### uwed Thread Starter Member

Mar 16, 2015
64
17
Thank you, a good starting point! Do you think the capacity would increase in case such rectifier diode dies would be in a little power module (diode bridge)? Probably not ... ?

4. ### #12 Expert

Nov 30, 2010
17,887
9,286
A dead diode that is shorted, therefore is not a capacitor, it's a conductor.
A dead diode that is open is probably still a capacitor.

5. ### uwed Thread Starter Member

Mar 16, 2015
64
17
Thank you for the datasheets! That answered my question.

6. ### crutschow Expert

Mar 14, 2008
16,503
4,439
But probably a much smaller capacitor since an open diode likely means a break in the internal connection so you would not see the normal junction capacitance.

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7. ### dl324 Distinguished Member

Mar 30, 2015
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1,059
Are you talking about reverse biased junction capacitance, or forward? When reverse biased, junction capacitance will decrease with increasing voltage. The opposite happens when forward biased.

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8. ### uwed Thread Starter Member

Mar 16, 2015
64
17
It is about a simple model of common mode current paths in a converter. So I thought about a parasitic capacitor in parallel to an ideal diode for the diode bridge. But according to comments from crutschow and dl324 it wouldn't work like this? I know there are good spice models available for such a task but for this project I use a simulator that works with ideal diodes and switches.