IRFP360 mosfet driver

[cosminnci]

Hello,

I want to drive a 220V led strip using the IRFP360 mosfet
for driving from an arduino pin I use a 4n25 optocoupler like the schematic attached.

so far I am having troubles driving the mosfet, over a limit the output voltage goes down.
I am using the pwm from the atmega, the default 976hz is too small I would like 7812hz or 62500hz
I was thinking the optocoupler cannot handle the switching and consider using a 6n137

is the 4n25 suited for this application or should I use something else?

[T3sl4co1l]

What is the light string?
What is the "8.3V" supply?
Do you have to do this with an utterly ancient MOSFET?
What significance is the frequency?  What purpose does it serve?

Whatever the frequency, to get useful switching, you need risetime < 1 / (20*frequency).  If this is for dimming, you should use an even steeper ratio.

MOSFETs can also switch only in one direction.  If this is an AC powered light, you need two MOSFETs.  I'm assuming you're switching a DC light here.

Single transistor optoisolators, like 4N25, aren't capable of switching much faster than a microsecond, suggesting a frequency below 50kHz.  In a circuit like this (with a weak pull-down and an incredibly massive gate charge), you'll be lucky to succeed at 1kHz.  Which I'm guessing is your problem?

Tim

[singapol]

Use a logic level mosfet, reason being normal type mosfet cannot be fully turned on by microprocessor output resulting in high resistance and heat built up in mosfet that's why your circuit failed. You can use faster opto coupler like 6N137.

http://selfbuilt.net/shop/Logic-Level-N-Channel-MOSFET-FQP30N06L

[Psi]

Check the pic again, He's using 8.3V from an opto not the mcu direct.
8.4V should be fine for a normal mosfet.

[cosminnci]

Thank you for the reply,
by light string I mean an 220V led strip
in the irfp360 datasheet I understood that the vgs is 10V
the purpose is for dimming the led strip
I use a rectifier bridge so the led strip is powered with DC

could you recommend a logic level mosfet that can handle more than 300V dc and more than 10A current.
so I should use an 6N137optocoupler.

[Performa01]

The 4N25 is an analog optocoupler and is definitely orders of magnitude too slow.

6N137 would be fine, except for the fact that it cannot stand more than 7V at the receiver end (the output transistor). This voltage cannot turn an IRF360 (or any IRF MOSFET I'm aware of) fully on, but might still be sufficient as I figure your LED string would not draw that much current anyway.

[BloodyCactus]

for driving mosfets I use the awesome MCP1407, has a logic level input and its output goes straight to the fet.

[han]

220V is it ac/dc?

[Seekonk]

I use the opto method for driving FET all the time at 10A with UNO, 490Hz.  The 10K resistor is too high, make it 1K or under.  There is no need for the 300 ohm which just reduces your drive.  In software I always eliminate short pulses at either end which only cause heating. Like to see a little higher drive voltage to fully turn on the FET.

[cosminnci]

@han 220v AC and passing trough a rectifier bridge for converting to DC
@Seekonk 490Hz still has a flicker I would try the 7Khz, how do you eliminate the short pulses, in my case it was heating too.

could I use 6N137 for optoisolation and MCP1407 for driving the IRFP360 ?

[bktemp]

Using a 6N137 and a MCP1407 is the correct way to drive the mosfet, but using several kHz for driving a large led strip is not good and not necessary unless you add an inductor for smoothing the current.
The flickering is probably the result of the PWM signal beeing modulated by the mains frequency. Try adding a capacitor after the rectifier to get a better dc voltage.

[electrophiliate]

+1 for the MCP1407 as a decent MOSFET driver, which will allow you to use a low value series gate resistor e.g. 10R or so for faster switching. For opto-isolation, if I recall even the 6N136 should be fast enough for this application, and can handle higher voltages than the 6N137 if 7V is too low for driving the gate of the FET. It may not be easy finding a logic level FET capable of 300V and 10A as requested, what is the current consumption of the lighting strip when fully on? The 8.3V intended for driving the gate should be OK for the IRFP360 even when considering the minor voltage drop of the gate driver. Where is the 8.3V from and is that all that is available? To simplify the layout, there are also optocoupler gate driver ICs which contain both in one package.

[cosminnci]

@bktemp I tried the capacitor after the rectifier but the dc voltage after the cap goes to 300+V and I think it would burn the led`s in the strip.

The 8.3v was produced by a RC transformerless supply from mains especially to power the optocoupler but it was a very low power supply.
for testing I use a different power supply or a battery.
the consumption is 14W/m and I need to power aprox 100m

[bktemp]

@bktemp I tried the capacitor after the rectifier but the dc voltage after the cap goes to 300+V and I think it would burn the led`s in the strip.

It depends on how the led strip works. Does it only use resistors to limit the current or are there active current sources?

The 8.3v was produced by a RC transformerless supply from mains especially to power the optocoupler but it was a very low power supply.

Maybe the problem was the rectifier. Since both use the same source, a rectifier and a simple capacitive dropper do not work very well together without modifications.

the consumption is 14W/m and I need to power aprox 100m

I would not use PWM for such a large load. 100m will form a large enough antenna to radiate the pwm frequency.

[cosminnci]

It is 60 leds /m and as I see it is 1 resistor 2 led groups, no other components.

I tried running the optocoupler from a battery and same results.

I will use 6N137 for optoisolation and MCP1407 for driving the IRFP360 and see how it behaves
should be much better than the current setup

[Seekonk]

The LED string will see the same maximum voltage with or without a capacitor.  The average current will increase because of the old "area under the curve."  You will not see 490Hz flicker, that is the mixing of the two signals.  I think you would be better playing with lower voltages.  Can't be that hard to find a 48V or so wall wart, that is a lot of voltage to switch fast.   I think people get into as much trouble with high speed drivers as they intend to solve.  I have no trouble switching with opto isolators.  I remember one case where this guy went through $120 in FET & IGBT trying to use a high speed driver at 490Hz because it would turn into an oscillator.   

[cosminnci]

I measured the dc voltage on the strip without and whit caps and there was a almost 50v difference if I recall right.

I have considered the 12v led strip option, but the price would be much higher,
for 12v I would need a supply at each 5 m and much more amps to drive

[cosminnci]

Hello,

I got the MCP1407 and want to do a test circuit for driving the IRFP360 mosfet I used a 300R gate resistor and a 10K pulldown.
while the MCP1407 is a mosfet driver can I just use a 10R resistor for the gate? I couldn`t find how should I do this setup.

[cosminnci]

Hi,
thank you for your answer, this is non commercial and is intended for a very large room, and is intended for use at probably under 10% that is why all the dimming and pwm needs.
ok, I will try with an 20-22 ohm resistor and no pulldown.

[T3sl4co1l]

A room-sized installation will definitely be a source of EMI!

Tim

[BloodyCactus]

when i use MCP1407's with my IRF640's, I use pull down on the MCP1407 input pin and no resistors on the outputs of the 1407 to the fet.

[cosminnci]

I made a test setup like the img attached

without c1 it was very unstable.

[oldway]

Another option would be to use a phase controlled triac with MOC3020 optocoupler.

[cosminnci]

I have tried the phase control but my coding isn`t that good, it worked but it didn`t had power at full, probably I did something wrong.
this version with opto and mcp does the job for now, soon I`ll make the test on the real deal and will see the results

Thank you for your help.

[oldway]

Life without Arduino still exist. 

There are very simple dimmers on internet.

For exemple,

http://www.powerguru.org/want-to-dim-your-leds-with-a-triac-dimmer/

Use your bridge rectifier to minimize flickering. (100 Hz instead of 50 Hz)

The only concern is with safety as this circuit is not isolated from mains.

For this reason, use a plastic potentiometer PIHER PC16SH for R1.

http://www.conrad.fr/ce/fr/product/445229/Potentiometre-rotatif-Piher-PC16SH-10IP06102A2020MTA-mono-02-W-1-k-1-pcs