50 watt led driver schematics required

[audiospecialist]

Hi


Did you see it's application note or datasheet ? did you see the example circuits which the manufacturer delivered ?



Best Luck
Goldsmith

I am trying to learn PI Expert Design app. I wonder do they show the final schematic for desired SMPS? I could not locate the schematic other than transformer infos. Am I missing something ?

I have checked some schematics and design examples.

Can I modify a computer ATX smps for the purpose ,it has IC2003. but whenever I turn it on the fuse blows. \checked the power transistors and diodes they are ok.what else could be the problem ?

 

[kam1787]

Can I modify a computer ATX smps for the purpose ,it has IC2003. but whenever I turn it on the fuse blows. \checked the power transistors and diodes they are ok.what else could be the problem ?

I am no expert on modifying ATX PSU but off-hand I would say you are reaching too far ----- 36V is far fom the nominal 5v. True you can get +- 12V but not at the current you want.

in the OP you said you wanted constant current - it is true that LEDs are current sensitive - but if the voltage is stable [unless you are changing the brightness in some manner] then the current is stable. A current limiter is easier to implement.

Unless you really know what you are doing I would never suggest 'experimenting' with mains-powered smps. "Goldsmith" went on a major rant about simpler smps [which are not mains-powered] but there is a reality you have to face.
Frying your LEDS is a distinct risk, and frying yourself is possible.

Learn to walk before you run...........if you are adament about mains-powered smps choose a project which is something smaller [in current], less critical. and easier to source.

 

[audiospecialist]

I am no expert on modifying ATX PSU but off-hand I would say you are reaching too far ----- 36V is far fom the nominal 5v. True you can get +- 12V but not at the current you want.

in the OP you said you wanted constant current - it is true that LEDs are current sensitive - but if the voltage is stable [unless you are changing the brightness in some manner] then the current is stable. A current limiter is easier to implement.

Unless you really know what you are doing I would never suggest 'experimenting' with mains-powered smps. "Goldsmith" went on a major rant about simpler smps [which are not mains-powered] but there is a reality you have to face.
Frying your LEDS is a distinct risk, and frying yourself is possible.

Learn to walk before you run...........if you are adament about mains-powered smps choose a project which is something smaller [in current], less critical. and easier to source.

Dear Kam,

I want to build something economical and compact. It is not for commercial purpose but for lighting a projector system at home.

At present the Led is working with a 120 va transformer coupled with a constant current source of 1500ma driven by 2n3773.all those components are which came handy.

I am trying to learn SMPS as well,which is quite a mystery and intriguing to me.

I have the resources of DIyer level(Tad above hobbyist) with my semi professional skills.

I do realize the hazards,but counting on experts onboard.

I am sure if I could successfully build this smps then I may be able to repair 3 nos ATX as well. probably hack them for something else

I have some hands on experience building couple of 100 watts invertors which was basic single transistor /capacitor oscillators to lighten Fluorescent lamps

Regards

 

[mtwieg]

The TOP261 should work fine for a 50W led driver, and it gives you isolation if you want it. But it's a flyback topology, so it's more complicated than the non-isolated buck types.

For current output regulation, you can just use a resistive shunt to sense LED current. If you want the feedback to be isolated, you will probably need an error amplifier on the secondary side, since the sense voltage will need to be boosted to drive and the isolator.

 

[audiospecialist]

The TOP261 should work fine for a 50W led driver, and it gives you isolation if you want it. But it's a flyback topology, so it's more complicated than the non-isolated buck types.

For current output regulation, you can just use a resistive shunt to sense LED current. If you want the feedback to be isolated, you will probably need an error amplifier on the secondary side, since the sense voltage will need to be boosted to drive and the isolator.

I haven't worked with IC smps, so I am being unsure .Does't mere adding a resistor effect the stability and oscillations?

I gues these circuits are highly sensitive to load and feedbacks.

would a lm339 suitable for voltage/error amplifier ?

One more question, How does the error is monitored with these chip? do they continually monitor and balance output or they trigger only when there is upsurge ? What I mean is how is Led driven ,does it sense the intensity of led corresponding to load variations?

 

[mtwieg]

I haven't worked with IC smps, so I am being unsure .Does't mere adding a resistor effect the stability and oscillations?

I gues these circuits are highly sensitive to load and feedbacks.

I wouldn't worry about a current shunt affecting stability. Certainly it's better than no feedback.

would a lm339 suitable for voltage/error amplifier ?

Ideally you should have a linear feedback loop, based on an op amp. A comparator will likely result in chaotic behavior or instability.

One more question, How does the error is monitored with these chip? do they continually monitor and balance output or they trigger only when there is upsurge ? What I mean is how is Led driven ,does it sense the intensity of led corresponding to load variations?

The duty cycle is normally controlled by a bias current driven into the control pin (C) by a phototransistor or something similar. That current is derived from whatever you're trying to regulate (output voltage or current). It's basically linear feedback, and is always active (except under fault or startup conditions).

 

[goldsmith]

I am trying to learn PI Expert Design app. I wonder do they show the final schematic for desired SMPS? I could not locate the schematic other than transformer infos. Am I missing something ?

Hi
The schematic that you have showed there , is good . it needs a bit change . if you are not an expert one in PCB design , you'll need the anti magnetize capacitor from primary to secondary to prevent unwanted damages .
Anyway
you can easily achieve what you need based on that circuit . you can use a TL431 instead of that zener but if precision isn't an important option for you a simple zener would suitable too .
You can use that schematic in forward mode which would be easier to design for you too . but if you're going to make a flyback one based on that you'll have to be careful of leakage inductance ( it should be as low as possible which depends on how you are winding your transformer )

Best Wishes
Goldsmith

 

[audiospecialist]

I am not an expert in pcb design,I have made some pcbs in cadsoft eagle which were audio related.

What is a forward mode?

what is an anti magnetize capacitor?


what are design consideration for the switching transformer?

Core permeability
winding pattern
air gap
winding tightness
winding insulation

I dont think leds would require high voltage regulation. high efficiency is welcome.I have two leds now ,making it 100 watts. i.e 36volts 3 ampere.

 

[Pato2010]

Also there is factory maded small compact transformers for these designs.

Can You tell me hoe to order such transformers ?
Can you give me contacts to these factories PLZ?