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a cool piece of silicon: Integrated SMPS controller and power switch

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Dr. Shark

Thu Jun 15 2006, 10:19AM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711

I just discovered this chip on ebay: "5H0380R Fairchild Power Switch(FPS)" which appears to be the simplest way to build a SMPS ever. Running at a fixed frequency, it has only four pins, and it requires no external components. I think it could be great for driving flyback transformers and other small gadgeds where you need an inverter but can't bother designing one. Finally no more messing around with NE555s or even TL494s when you need to drive and PWM something.

At 1â‚¬ / piece and 100 available, I think I'll get a few.

Data sheet:

Marko

Thu Jun 15 2006, 10:50AM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

It can withstand only a hundred or two miliamps in real operation and it will really be a puny thing to drive flybacks.

It may only serve as a small SMPS, cool for some aplications as we won't need a mains transformer.

Interestingly fairchild didn't give any schematics regarding transformer and feedback, output voltage adjust, and not doing neural network's bidding would probably just result in heaps of blown IC's.

Such weaklings are pretty hard to get going actually, and they use to be more unreliable than a simple mains transformer.

Same is with single-transistor SMPS's we see in ATX supplies wich are actually impossible to get going unless they are completly copied, exactly same transformer must be used and nothing must be changed in circuit (otherwise it will just blow up).
And their duty cycle control is also poor.

I guess you need to find an example application schematic for this IC.

Dr. Shark

Thu Jun 15 2006, 11:13AM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711

Firkragg wrote ...

It can withstand only a hundred or two miliamps in real operation and it will really be a puny thing to drive flybacks.

Why would that be, the data sheet says it can handle 3A continously and dissipate 75W. Maybe the DIP version is worse, but I am talking about the TO220 here.

Marko

Thu Jun 15 2006, 11:27AM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

whoops, i watched the table of 5M0365 wich is 400mA CW only.

I vote it to be a small, neat low-voltage SMPS, flyback driver may be a try altough there are things that can pump much more power at much higher efficiency, until the transformer dies, for just few more conponens.

Dr. Shark

Thu Jun 15 2006, 12:01PM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711

Sure, it could be used for that. I imagine hooking it up to the transformer from an ATX PSU or from a solid state 12V halogen lamp supply it could make for a very nice 200W 12V supply, hopefully without all the hassle of hacking the ATX / halogen supply itself.

I do think however that it would be great for flyback transformers too. I am blowing them faster than I can aquire new ones, so if this chip works to drive them at 100W reliably, I would be happy.

Marko

Thu Jun 15 2006, 12:48PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

You will have to rewind transformer since you need a feedback winding.
Sometimes you can find ones that have it but they are pretty rare in ATX (I had one mini 80W atx supply that used HV side flyback converter and IC was powered by feedback winding, all others use just one primary and a halfbridge.)

Number of turns must match frequency, and you need an example schematic if you wish to start anything with that IC (guessing you don't want to blow heaps of them up before succeding something)

Steve Conner

Thu Jun 15 2006, 12:49PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Reliability is a function of the whole system. If you screw up the design of the transformer and snubber network in a flyback converter, such that it sends big spikes back into the switching device, you'll blow it just the same, no matter if it's an integrated device or a good old IRFP460. The way to make a reliable SMPS is to understand how it works and design it properly, not to buy some magic chip.

Having said that, if the chips are only 1e each, who cares.

Dr. Dark Current

Thu Jun 15 2006, 03:25PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

joe wrote ...

Sure, it could be used for that. I imagine hooking it up to the transformer from an ATX PSU or from a solid state 12V halogen lamp supply it could make for a very nice 200W 12V supply, hopefully without all the hassle of hacking the ATX / halogen supply itself.

I dont think so. Once I dismantled an old VCR SMPS, it had one of those self-oscillating drive ICs. I guessed the SMPS to be about 50W. When I looked at the datasheet, it said the FET has 600V and 6A. so I think the IC you found, will be ok for maybe 30W.

J.M.

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