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Abs max voltage of TRM pin of Power module? (TUNS500F)

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cupoftea

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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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  • Overcurrent limit circuit.pdf
    167.7 KB · Views: 78
  • Overcurrent limit circuit.zip
    2.8 KB · Views: 67

Hi,
(Sorry to ask again about this power module, but i thought info could be useful to others too)
We want to use the TUNS500F ACDC power module for 48V, 7A5 PSU.
Does anyone know the absolute maximum voltage that can be applied to the "TRM" pin?
The Applications manual, on page "TUNS-26" talks about it, but doesnt give the value.
There's a family of modules, and the literature is a little unclear as to what page applies to which particular module.

datasheet
https://en.cosel.co.jp/tool/tag/pdf/SFE_TU.pdf

Instruction manual
https://en.cosel.co.jp/tool/tag/pdf/CME_TU.pdf

Applications manual
https://en.cosel.co.jp/tool/tag/pdf/TU300_500_700_manual.pdf
 

I think it's quite simple. TUNS500F is designed for optional external voltage divider to adjust the output voltage, not an active circuit connected to TRM pin. By having an internal series resistor resistor and standard substrate diodes at the connected error amplifier, I would nevretheless expect sufficient voltage tolerance for your application.

A problem not yet adressed is that the current limiting circuit is supplied by the SMPS itself, respectively the applicable voltage range is rather limited. It's particularly unable to perform a short circuit limit. The design doesn't look well considered.
 
A problem not yet adressed is that the current limiting circuit is supplied by the SMPS itself, respectively the applicable voltage range is rather limited. It's particularly unable to perform a short circuit limit.
Thanks, and thats a good point. In this case, the TUNS500F has current internal current limiting to 14A if ever the output current goes above that...so that would deal with the case of short circuit. I believe it hiccups back on if ever the 14A limit is reached.

Our normal load is up to 7A5.....but we still want current limit if current trys to go above 10A. I admit the circuit is cheap , but then again, its kind of all we need.
 

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