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Hi,
I design a board based on LM25148. I also got PCB review for it.
Now i am testing the board.
I noticed that as i increase the load current, the input voltage at converter start dropping drastically so the output voltages..
The board is designed to output 7.4V and minimum input voltages will be 8.4V.
In the given data, the input supply is setup at 8.4V on supply and 1st column show the voltages measure at input terminals of the converter.
Input Voltages V (drop shown at Meter) | Output Voltages V | Load current A |
8.4 | 7.39 | 0 |
7.7 | 7.38 | 2 |
6.9 | 6.79 | 4 |
6.2 | 5.95 | 6 |
If i increase the power supply voltages to maintain input voltages at 8.4V then it give desire output. Now the question is why input voltages are dropping? As input voltage drop so obviously output will be less than input.
Hello Ali,
Need to know what the input voltage is dropping, I suspect the input supply is in current limit, the LM5148 is doing what it needs to do to best regulate VOUT from a lower that expect VIN.
hope this helps,
David.
Hi David Baba
Thanks for your reply. The supply isn't ij current limit. I setup current at 10A on power supply.
When there is 0A load current then the input Voltages are 8.4V but same input start dropping as i increase the load current. The above table 1st column shows the voltage drop in input from 8.4V.
Thanks
Hello Ali,
Its not our device. There is nothing that would make the input supply drop other than the input supply itself, suggest getting another supply. Hope this helps.
David.
Hi,
I will test it on some other power source. Can you confirm me max current rating of this device?
I remember, on datasheet it was 20A and i designed 8A continues and 12 to 15A peak current for this board
Hello Ali,
Yes, the device is capable of these output currents, hope this helps,
David.
Hi David Baba
I found the problem. It was power supply cables issues. I recently bought new one that are counterfeit. The issue resolved when i changed the cables.
Thanks for all your help.