What is the maximum volume for this offline power supply spec?

[treez]

Hi,
There is a need for an offline PSU of power up to 150W.
Vout is 24V
No fan
Open frame
Isolated

Eg, like EPP-400-24 which is £47 per 100 pces.

...Why does nobody buy these? People always say that they cant use them because...
1...they are likely to go obselete, leaving them with a mechanical fixture which is then useless.
2...They cannot be bought in high volume at short lead times.

Are the above true?

What is the maximum volume where above that, you would always design your own in-house (or from a consultancy)?

 

[Easy peasy]

anything above 1000pcs per batch ( anum ) you would consider doing in house - as you get guaranteed quality control, and you can get a manufacturing house to make 1000 in a batch no worries - you can also vary your own design easily ( e.g. 24V or 27V - float ) - and you get guaranteed supply in the shape you want.

 

[treez]

Thanks, good point about making your own so that you can have special features like variable output voltage.

However, even in that case, as you know, you can just by a post regulator to convert the 24V into 27V, or whatever.......or indeed, once the main offline conversion job has been done, its as you know, very easy to in-house design a DCDC converter to get from 24V to whatever voltage, even if variable vout.

So i am wondering, with the cost of these open frame offerings being so cheap, why should any company fork out money for a custom designed offline PSU?

 

[Easy peasy]

there are always limitations for cots psu's, often emi, or susceptibility, or crappy thermal performance, lack of transient immunity, but security of supply is the biggie, you mention post converters, but really for a 250 watt psu, at 24v out, why would you include a 24 - 27v converter requiring more space & loss of efficiency & cost, when you can just adjust your own psu ...?

 

[treez]

sorry, i forgot to add, the battery charger bit is only 350mA max (from the 24V). but yes i see your point......but i always hear that offtheshelf converters are so much cheaper, due to them having been made in some huge mass production process.

To be honest, this power supply will actually be on pretty much <10W load for the vast majority of its life.......

 

[Easy peasy]

In that case design in a PI solution for 15W, and have the other more powerful converter sitting there ready to go ( fet's off but ready to go flat out ) - this will give you good longevity and very good efficiency ...

 

[treez]

You're absolutely right, that is the way to get lowest standby power, which is potentially very important. However, as you know, the jack_the_lad cheapskate way is to just shove a 15W DCDC battery charger on the output of the offline PSU.

And many an engineer is often kept out of the purchasing loop, and so wont know the cost difference between doing this with a custom design, and doing it with off the shelf power supplies. And ditto that, but this time take the situation of a company that already owns its own SMD soldering business, and already does other PCBs (non-power) with that, (company populates its own PCBs with its own SMD machines).....how does the custom_design vs offtheshelf conundrum work in that case.

Its always been a mystery to me what the actual price differential is between custom design and offtheshelf buying. But thanks Easy Peasy for your post#2 above where you give actual figures.

I mean, i wouldnt mind betting that eg Meanwell , if one showed them significant volumes, would offer a phenominally cheap offtheshelf solution, and even modify one of their existing offline, open frame 150W solutions to suit.......and i almost bet my shirt that they'd viciously price it well under the cost of any company doing it as a custom design.......but as discussed, no engineer would know...as final purchasing "deals" are always done at the top level in a company, and the engineer hasnt got a clue.

I am always amazed about the way managers in companies always ask what is the price of a custom design for xxx Watts and xxx volume....when no engineer would ever know this. (unless they owned their own consultancy)

 

[Easy peasy]

The engineer can always request a chat with the CEO to get a perspective on pricing / outsourcing / other matters.