Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Power module will be damaged by added Overcurrent limit circuit?

Flyback

Well-Known Member
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
 

Attachments

  • Overcurrent limit circuit.pdf
    167.7 KB · Views: 13
  • Overcurrent limit circuit.asc
    10.3 KB · Views: 9

alec_t

Well-Known Member
Most Helpful Member
Do you think it will damage the TUNS500F “TRIM” pin, due to >5V experienced on that pin? (>5V on TRIM pin when overcurrent happens)
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?
 

Flyback

Well-Known Member
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
 

Pommie

Well-Known Member
Most Helpful Member
Silly suggestion, add a load that will always take 3A (10.5-7.5) and the automatic current limiting will kick in. :D

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

Mike.
 

alec_t

Well-Known Member
Most Helpful Member
i am not aware of an "ITRIM" pin on the TUNS500F module?
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.
Limiter.jpg
 
Last edited:

noman113

New Member
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
It's confusing to me. I don't see a 48V 7A5 version. There are 6A5 and 10A5 versions.
 

alec_t

Well-Known Member
Most Helpful Member
our max load is 7A5....but we want to limit it when currents of 10A or more are drawn.
The module has a built-in current limit of 10.5A. Won't that suffice?
 

Latest threads

Top