Drive RGB Led using MOSFET IRF9530

Hello,

I have everything working except the IRF9530 part.. When I use a simple transistor BC547 it works but gets too hot because of the high current.

The RGB leds are common anode LED if I am correct ( one + and three - for the colors ).

Does someone have a example how to hook up the IRF9530 with arduino? Thanks!

this image isnot the one you are using but have same pin in

G : the gate to turn it on or off

D : Drain use it to power your led or other(D -> Led -> Gnd)

S : Source where you take your current to send it to your Drain (your is a P-Ch so connect it to Vcc +)

Remember to add a resistor between the arduino and the Gate

I have everything working except

Hey we are not mind readers, everything working on what? What sort of current is too much / too hot.

These things matter and will help us give you the best advice. :slight_smile:

Mosfets and microcontrollers can be a nightmare sometimes.

A mosfet requires much more than 5V across the Gate and the Source to trigger it. Unless its a logic level mosfet which can work off 5V.

The IRF9530 is a power mosfet and as such hooking it up directly to the output of a microcontroller won't work properly. It will turn on but not completely, so it will still be in its linear region which could make it overheat and be innefficient. There is also the problem of the Gate to Source and Gate to Drain capacitances, which is why you need to properly drive a mosfet to turn in on.

How much current is flowing in your LED? Perhaps you could consider using a power BJT like a TIP32. Or a logic level mosfet. The International Rectifier logic level mosfets I have used have "IRL" in the part number, or an "L" somewhere.

You could try building a driver circuit, but its better to buy a driver IC. You get high side drivers and low side drivers. Low side drivers are the simplest to work with but it all depends on how you want to wire stuff up.

Thx al.

I am building standalone moodlight with RGB strips.
At the moment the strips are using 500ma each channel ( test setup ). in the end I need about 5A - 7,5A per channel.

Thx to Madrang I got it working but like zageek is saying, the leds are not on/off 100%.

I want to try to get it working with the 9530 mosfet since I already bought them.

If that fails I can still get those devices from my local store:
TIP127
BD677
TIP122
STP80NF10
IRF3205
IRF830
IRF530
2N3055 (TO-3, 15A, 60V)
2N2955 (TO-3, 15A, 60V PNP)
MJ15003 (TO-3, 20A, 140V)
MJ15004 (TO-3, 20A, 140V)
BTA08-600
BTA16-600
FDP6035AL (logic FET 48A 12mOhm TO-220)

Edit:
zageek, do you have some driver circuit example to use with arduino?!

you could use your transistor to drive the Mosfet just send Vin to your transistor Collector and use it to power the Mosfet gate... if you need a schematic i will make one.....

Thx I tried that but then the led's just stays on.

It would be very handy if you could a schematic so I can compare it with my setup.

You can try this.

It not the best solution especially if you are using 5V to supply the driver. If possible try and power the driver and LED/Mosfet section using a higher voltage like 12V or 15V from a separate power supply.

Or you can buy a driver IC like an IR2110 if available. They can get a little costly depending upon where you get them, but they "generate" the right voltage to drive the mosfet as well giving enough current to fully charge up the mosfet's capacitances.

Picture link does not work here...

I already have 12 Volt beside the 5 Volt for arduino, so that's not a problem ( the RGB strips are 12 Volt ).