Power module will be damaged by added Overcurrent limit circuit?

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Flyback

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Hi,

We are doing a 48V 7A5 PSU with TUNS500F ACDC power module.

We want it to limit current if a 10A load is connected, so the contractors made the attached overcurrent circuit as shown. Do you think it will damage the TUNS500F “TRIM” pin, due to >5V experienced on that pin? (>5V on TRIM pin when overcurrent happens)

Attached is a representative LTspice sim of the added overcurrent circuit, and a PDF schem of it

TUNS500F datasheet (page 8...)
https://en.cosel.co.jp/tool/tag/pdf/SFE_TU.pdf

Page “TUNS-27” of the below, says TRIM pin should not have >5V applied to it….
https://en.cosel.co.jp/tool/tag/pdf/CME_TU.pdf
 

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Flyback said:
Do you think it will damage the TUNS500F “TRIM” pin, due to >5V experienced on that pin? (>5V on TRIM pin when overcurrent happens)
Click to expand...
Quite likely. It's unwise to exceed module ratings. Your sim shows ~10V spikes on that pin.
I may be misunderstanding the circuit, but why is the over-current protection being applied to the VTRIM pin rather thn the ITRIM pin?
 
why is the over-current protection being applied to the VTRIM pin rather thn the ITRIM pin?
Click to expand...
Thanks, sorry i am not aware of an "ITRIM" pin on the TUNS500F module?
 
I'm confused. There isn't a 48V 7A5 version. There is a 6A5 and 10A5 version.

Mike.
 
Thanks, yes, our max load is 7A5....but we want to limit it when currents of 10A or more are drawn...which may happen sometimes
 
Silly suggestion, add a load that will always take 3A (10.5-7.5) and the automatic current limiting will kick in.

Can you reduce your current requirements to 6.5A and use a TUNS300F?

Mike.
 
Flyback said:
i am not aware of an "ITRIM" pin on the TUNS500F module?
Click to expand...
Mea culpa. I was looking at the wrong module.

Edit:
A ~12k resistor between D2 and the pot wiper seems to tame the 10V spikes and bring them down to 5V.
 
Last edited:
It's confusing to me. I don't see a 48V 7A5 version. There are 6A5 and 10A5 versions.
 
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