Input protection setting for DC-DC converter

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MD MUBDIUL HASAN

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Hi there,

This post is very easy one for you who knows better.


I am confused to set some values.
My DC-DC conveters input is 250-650VDC and output is 24V/5A. Its use for PV battery charger.
Take a look here,


I have few more query,

1. My boss want me to put some common ground ZNR” Transient/Surge Absorbers, in folloing manner, https://www.farnell.com/datasheets/2244565.pdf

2. Dont you think he needs it unnecessary for protection since there is 2 cap, 1 noise suppreser and rersistor are available.

3. He wants to add a fuse in pin 1 to R24, not sure why?

4 Can you imagine any idea to use R1-3? Those are 1 Mohms.

6. He wants to add a LED indecator for power output, for 5A current whats your idea?
 
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We do not understand the relationship between 250-650VDC and ground. Pin-1 could be at 650 while pin-4 is at 0V. OR Pin-1 = +300 and pin-4=-300.
I think you want to limit Pin1 to 4 at 700V and limit Pin1,4 to ground at 700. Three parts!
3. bad idea.
4. R1,2,3 are to discharge the capacitors. (C2)
6. Need to see more circuit.
 
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Yes, well noticed.
Let assume pin 2 and 3 are not connected
1. You did not talk about ZNR, does it meaningfull configuration.
2. Does L1 works with this datasheet? https://www.we-online.com/catalog/datasheet/74482210002.pdf.
3. Discharging resistor values are ok? Do you want me to see here, http://hyperphysics.phy-astr.gsu.edu/hbase/electric/capdis.html
Take a look the image below, my minimum required ripple current is 11.04 A. The output filter is a simple LC filter consisting of L2 and C7 in the typical circuit. We need to design the filter to have a cutoff frequency much lower than the operating frequency, so that it will effectively reduce the switching noise observed at the output.

Where the LED indicator should add?
 
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MD MUBDIUL HASAN said:
Discharging resistor values are ok?
Click to expand...
The laws I live under said, ' unplug power, open box (screwdriver) reach in and touch capacitor. By this time the voltage needs to be below 48V. ' It takes two pages of words to say that. LOL
MD MUBDIUL HASAN said:
reduce the switching noise observed at the output.
Click to expand...
What frequencies do you see on the output? A big L and C will help at the switching frequency. But there might be 100mhz noise that will pass though the big L and the big C is not good at mhz. You might need a small LC right at the output connector. I cannot test from here.
MD MUBDIUL HASAN said:
You did not talk about ZNR, does it meaningfull configuration.
Click to expand...
I would use 3 parts. Or one part. I do not see how 2 parts helps.
 
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