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Mean Well D-60A power supply question??

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rfranzk

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Hello All,

I am working on a project that needs a 12 volt dc supply of 2 to 3 amps max. I found this Mean Well D-60A dual power supply in my stash and wondered if I needed to load the 5 volt side for it to operate properly of if it could be left floating as I don't need the 5 volt side at this time. I don't see anything in the datasheet other than current is .3A ~6A.

If I should load the supply I was thinking of a 10 ohm 5 watt power resistor. Is this sufficient and should it be the finned cooled type?

Thanks in advance for your help.

rfranzk.
 

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Tony Stewart

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This is a full range design so no preload of 10% needed. I would expect tight coupling between secondaries so you can tell even the forward converter is regulated by the 5V for 0.5% load regulation and the 12V tracks by coupling has 4% load regulation. You might be able to raise the 12V voltage by >1% by loading down the 5V with 10% of rated 5V power, this may not be necessary for your app.
 

spec

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Hello All,

I am working on a project that needs a 12 volt dc supply of 2 to 3 amps max. I found this Mean Well D-60A dual power supply in my stash and wondered if I needed to load the 5 volt side for it to operate properly of if it could be left floating as I don't need the 5 volt side at this time. I don't see anything in the datasheet other than current is .3A ~6A.

If I should load the supply I was thinking of a 10 ohm 5 watt power resistor. Is this sufficient and should it be the finned cooled type?

Thanks in advance for your help.

rfranzk.
Hy rfranzk,

Yes, you need to load both supply lines with at least the minimum current shown against each supply line on the data sheet. It your application does not achieve this, use a dummy resistor as you say.

If you do not do this the power supply may fail to regulate or do other weird things.

spec
 
Last edited:

MikeMl

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P = IE = 0.3*5 = 1.5W
P=I^2*R
R=P/I^2 = 1.5/(0.3*0.3) = 16.7Ω

D60A.png
 

Tony Stewart

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The min current is needed for tolerance on the high side, not for function or stability as often needed on old designs. Since the 5V is the primary feedback and 12V is feed forward, And if there is no load on either, you should still get 5 & 12 V but perhaps both may be on the higher tolerance end or above. There is a hiccup recovery for OVP. Since 5V is not loaded except share common flux with 12V that should give sufficient feedback for the 12V.


If you need better than 6% total tolerance error, one can always tweak it.

Test it both ways to see who is correct.

If necessary, one can make a light using a 1W White LED with a 1W 6.6Ω series to 5V.

What are you using it for ? LEDs?
 
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Nigel Goodwin

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My problem with this, is that (as always) a regulated SMPSU with two outputs is only regulated on a single output, this would normally be the 5V output in this case, the one the OP doesn't want.

In such a case the 12V output won't be very well regulated (as there's no feedback from it), and it's likely to need some load on the 5V rail in order to give the 12V rail at least a chance of been 'close' to 12V.

Personally I'd prefer to mod the PSU so it regulates from the 12V rail instead of the 5V one.
 

dr pepper

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That isnt always the case nige, I've modded a few old pc supplies for different purposes, and I found them all to have feedback on both 5v and 12v, a resistor from each going to a common point with another resistor to ground.
Doesnt mean to say the meanwell is the same, and also your still right regulation is designed for both rails to be loaded.

Fran if your load is constant then if you load the 5v rail by a similar amount %age wise to the load on the 12v rail you'll get reasonable operation, however if the load on the 12v rail isnt constant the only way you'll get good regulation is to mod the supply as Nige pointed out.
 

Nigel Goodwin

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That isnt always the case nige, I've modded a few old pc supplies for different purposes, and I found them all to have feedback on both 5v and 12v, a resistor from each going to a common point with another resistor to ground.
Fairly obviously it can't regulate two rails at once, as they don't adjust separately, presumably it's only to prevent catastrophic increases in one or the other rail?.

Incidentally, a common failure on Freesat boxes is the 1000uF on the 5V rail, and if you don't catch it in time it destroys other components (presumably big chips :D) rendering them unrepairable - as the PSU tries desperately to maintain the 5V rail the other rails go sky high.

Doesnt mean to say the meanwell is the same, and also your still right regulation is designed for both rails to be loaded.
The block diagram in the datasheet shows it only having feedback on the 5V rail.
 

Tony Stewart

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True the load regulation is 12x worse than 0.5% on the secondary output, but it is not correct so say there is "no feedback" because the feedforward mode shares mutual coupling flux so the primary output regulation is adequate shared flux so that with 6% overall worst case error on the secondary output,which is including, line, load and ratio error tolerances when the current ranges or max power is not exceeded.

As for minimum current, this used to be manditory on old designs with inadequate phase margin. These designs have significantly improved for phase margin. Typcially the voltage would keep rising with no load. But the user wants 2-3 Amps and has not specified 0-3 Amps or tolerance, so we can only guess. Usually 1% to 5 % on 5V and 10% on 12V for most applications.

A mod to change the feedback point to 12V with a 5/12 voltage ratio is certainly doable if the OP is comfortable doing that.

In having qualified such designs from OEM's and worked directly with world class designers, from Hammond, Brown, Power One, Murata, Lambda, Shindengen ,I am fairly confident. but your mileage may vary.

I am familiar with epic failures from Packard Bell PSU, but not Freesat, I realize if the OP did the opposite, and loaded the 5V only with Pmax, we would expect the 12V to rise 4%, but in underdesigned or mismatched loads on multi-output feed forward converters, lack of mutual coupling flux can become catastrophic.


Meanwhile, Meanwell :) has an excellent approach with hiccup, OCP, OVP, and OTP protection correction builtin.

Freesat market is often cost tradeoff with quality and HUMAX was known to use low quality caps.
 
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rfranzk

Member
Thanks for everybody's feedback. I am fabricating a project with multiple mass flow controllers and the controllers come with a 12v wall wort type supply. I want to chop these and replace with one larger capacity supply. Upon further digging I found another supply that is single voltage and has some current overhead available if needed.

Mike, I wasn't sure if the .3 A was considered minimum load hence my question.

Thanks again for all your help and the discussion was quite interesting.

rfranzk.
 

dr pepper

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Nige.

Yes probably, I think the idea is to regulate an average loading of both rails, its possible to get one rail low and the other high.

I have a freesat box, if it does that its going in the bin.

Didnt see the block diagram, sorry my bad.
 

KeepItSimpleStupid

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rfranzk

Did a project with Tylan FC-260 MFC's BUT it didn't work out for computer control. I forgot about the ground loops. It was a 6 channel readout box that someone in-house put together. I managed to modify it to make it easy to change the range. e.g. FS/Gain and decimal point. The potentiometer setpoints were referenced all the way to the MFC boards, so no ground loops there except when you try to connect a computer.
 

dr pepper

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Yep mines a grundig. I have 2 of em.
 

dr pepper

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Found it, doesnt state voltage, esr meter says its a fraction of an ohm, so I wont mess with it for now.
Had a look at some other caps too, the set sometimes switches off then back on a split second later, though that might be the telly, its a crt goldfish bowl pile of trash, I dont really care about spending a load of cash just to watch adverts in hd.
 

Tony Stewart

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since ESR is inverse with C, the product is constant for a given family of parts.

ESR*C ~100 us or Ohm-uF. this may generate too much ripple V for some power load ccts.

Low ESR is ~ 10us. more or less. one I have seen is <1 us
 
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