High frequency square waves through a standard rectifier, how to test functionality?

Thread Starter

LikeTheSandwich

Joined Feb 22, 2021
151
So I have a bridge rectifier, I think it's the 8A from this data sheet (although I'd swear it said 1000V on the package when I got it...packaging I no longer have...) but anyway, I want to test it with 15kHz square wave AC to see how it performs. How do I test it exactly, that is what do I look for on my oscilloscope to determine its performance, or if its leakage current is too high, etc?

EDIT: I understand that with diodes there may be some sort of delay time between switching between allowing current to pass through and blocking it (hence schottky diodes which allow for high speed switching). But I don't know what sort of switching frequencies are good for what sort of diodes/rectifiers, so I want to test for that.
 
Last edited:

Ian0

Joined Aug 7, 2020
5,097
The figure you need is the reverse recovery time. As that is not present on the datasheet, it would suggest to me that this rectifier is designed for 50/60Hz operation and is not suitable for high frequency use.
 

Thread Starter

LikeTheSandwich

Joined Feb 22, 2021
151
I assumed that to be the case, but how would I test it? I managed to test it with no load at 5V using an Arduino device and it seems to be OK (I'm getting about 4.7V on the other side), but it's an Arduino so I can't put very much load on it anyway.
 

Ian0

Joined Aug 7, 2020
5,097
I would insert a shunt resistor on the AC side, and monitor the current that way. If there is a reverse-recovery problem, whenever the AC changes polarity you will see a spike in the current as the diode continues to conduct when it should have turned off. Something like a 1N4001 has a reverse recovery about 1.5us, a big bridge rectifier is probably even slower.
 

Papabravo

Joined Feb 24, 2006
18,408
What are the high and low voltages of the square wave? From an Arduino it would probably be 0 to 5 volts. I don't know how you were measuring 4.7 volts, given my understanding of your description of the circuit. WARNING: yelling begins here -->
WHY IN BLAZES DO YOU THINK A VERBAL DESCRIPTION OF WHAT YOU ARE DOING IS ADEQUATE TO HELP US HELP YOU?!!
A schematic diagram of your setup is essential, including the voltage levels on the square wave.
 

Thread Starter

LikeTheSandwich

Joined Feb 22, 2021
151
What are the high and low voltages of the square wave? From an Arduino it would probably be 0 to 5 volts. I don't know how you were measuring 4.7 volts, given my understanding of your description of the circuit. WARNING: yelling begins here -->
WHY IN BLAZES DO YOU THINK A VERBAL DESCRIPTION OF WHAT YOU ARE DOING IS ADEQUATE TO HELP US HELP YOU?!!
A schematic diagram of your setup is essential, including the voltage levels on the square wave.
I made a square wave with +5 to -5 with the Arduino. 4.7V is the rectified voltage I was measuring through the rectifier.
 

DickCappels

Joined Aug 21, 2008
8,705
I think @Ian0 did a good job of answering your question.

Also look at the capacitance vs reverse voltage plot. That suggests that to get a good idea of how good it is at switching while using Ian0’s method is to have a filter capacitor with a load across it on the bridge’s output.
 

crutschow

Joined Mar 14, 2008
29,779
Below is the LTspice simulation of a 1N4007 diode.
Note the large reverse recovery current and time.
Edit: That will generate about 5mA average of reverse current for the conditions shown.

1652885994703.png
 
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Papabravo

Joined Feb 24, 2006
18,408
Using a standard bridge rectifier with a bipolar supply (-5,...,+5) you will experience more losses than you will get by making a discrete bridge rectifier from Schottky diodes. In the case of the bipolar supply you can see the difference in the average values when the input source swings between 0V and +5V

1652897377133.png
 

Thread Starter

LikeTheSandwich

Joined Feb 22, 2021
151
I've tried googling for high frequency bridge rectifiers and couldn't find anything. Does anyone know how to find one online, or should I just DIY one with 4 Schottky diodes?
 

Papabravo

Joined Feb 24, 2006
18,408
I've tried googling for high frequency bridge rectifiers and couldn't find anything. Does anyone know how to find one online, or should I just DIY one with 4 Schottky diodes?
If this is a one-off project, I would use the discrete Schottky approach if you feel it offers an advantage and can handle the voltage and current. What Schottky diode were you considering for this purpose? If you have not picked one out, might I suggest the selection guides from Digi-Key or Mouser. They will also give you the quantities they have in stock, which in these days will save you the agony of designing in a part and then finding it is pure unobtainium.

I'm not sure I have ever seen one that was characterized for high frequency operation. If you like, I'll do a frequency response simulation of one if I can locate a model for a potential diode you might use.
 
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