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Simple POL module, what's with UL, CSA and CE approvals?

Hi

I am looking at POL module for a small run project

I stumbled across the CUI simple 3 pin module:

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It is UL, CSA and CE approved

Reference to a lot of standards:

_____________________________________________________ safety approvals UL 60950-1 EMI/EMC EN 55032, EN 55024 conducted emissions CISPR22/EN55022, class B (external circuit required, see Figure 4-b) radiated emissions CISPR22/EN55022, class B (external circuit required, see Figure 4-b)

radiated immunity IEC/EN61000-4-3, 10V/m, class A

see Figure 4-a)

required, see Figure 4-a) conducted immunity IEC/EN61000-4-6, 3 Vr.m.s, class A ____________________________________________________________

Ok. So it makes sense that it complies to for example EN 55032, which deals with emission, because you want to be able to pass EMC when you buy a POL module that you cannot modify in any way

Then there's a reference to UL 60950-1 which is a safety standard. This is a non-isolated POL, so not much safety about that, besides it must not catch fire in case of a short of the output or if 2 traces on the PCB is shorted (single fault injection on PCB due to distances less than the creepage requirements for ELV circuits)

Anything I am missing about the 60950 and the reason for complying to that standard?

Looking further, this Torex module does not mention any standards:

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The Recom module is encapsulated, so is probably easier to approve, since the potting makes the tests of shorts on the PCB void:

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Thanks

Klaus

Reply to
Klaus Kragelund
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Those little 3-lead switchers are great. Most will also convert positive to negative.

The XP SRH05 accepts up to 72 volts in.

Reply to
John Larkin

That one you specified has an input voltage of around 24V. Not much to be unsafe about there. Less than 30V. Maybe it doesn't catch on fire and burn the cheese cloth ?

It's just s simple buck converter.

If whatever you are putting it into needs a UL listing, then that spec might or might not be necessary. Then again, you might be needing some totally other spec to list to ?

Reply to
boB

Yes, if you use any component, it is not allowed to catch fire, so the design is critical to be sound from the POL supplier side

Also, for approval one does single fault injection on a PCB. For resistors that is open condition, caps closed AFAIR. So that also needs to be done on the POL module

What do you mean by other spec?

Reply to
Klaus Kragelund

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Don't be a jerk. Nobody likes jerks.

Most 3-lead step-down converters are.

My customers build airplanes and ships and rockets and gigabuck semiconductor fabs. They don't seem to care about UL or CE or FCC or ROHS.

--

John Larkin      Highland Technology, Inc 

The best designs are necessarily accidental.
Reply to
jlarkin

Not sure why you said this ?

Cheese cloth is what UL and others use to measure flamability.

Reply to
boB

Other UL documents or specifications to be listed to.

That would most likely depend on what UL specification your product is listed to

For instance, we certify a lot of our stuff to UL 1741

Reply to
boB

Seems like you were disputing the 72 volt rating on the XP part. Maybe not.

I thermal image boards and then measure surface temperature of anything that looks hot.

--

John Larkin      Highland Technology, Inc 

The best designs are necessarily accidental.
Reply to
jlarkin

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Huh, I didn't know that. I like the little three terminal switchers too. Wall wart with 24V out and you can make all sorts of voltages. I tested a number (3 or 4) of the CUI's to destruction. They all were fine with any resistive load... thermal and short circuit protection. I didn't try big capacitors, or inductors. They only way I broke 'em was with an over voltage.

Nice little units. I'd like a negative one that takes -24 Vin and gives

-15V out at 1 amp. No one likes negative voltages these days. :^)

George H.

Reply to
George Herold

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