Which Transistor to drive a 12V - 180W heater wire

Hello There !

i am looking for your advice and expertise on how to drive safely a 12V / 180Watt heating wire with an arduino.

The current would therefore be around 15 Amps.

this is my wire : Câble chauffant 2 m Arnold Rak HK-12,0-12 180 W noir | Conrad.fr

and i found this transistor : https://www.mouser.fr/datasheet/2/240/Littelfuse_Discrete_MOSFETs_N-Channel_Trench_Gate_-1856507.pdf

however, not sure if the arduino can deliver enough current to comfortably charge the gate, the Digital outputs being limited to around 40mA.

should I use 2 stages of transitors ?

thanks in advance for your feedback :slight_smile:

Regards,

Hi @
the bad news is that the arduino pin output does not support 40mA output.
The recomended maximum that must be drained from an Arduino output is 20mA.
But this is the maximum, and normally you don't work with the maximum.

PS: Sorry for my mistake, Mr. @wildbill is correct.

Somewhere on the web.

The good news is that this transistor (MOSFET) that you posted in the datasheet only only need 100 nA (nano amps) as a gate current.

GSS VGS =  100 nA

Another good news is that it has a maximum Vgs of 4.5V, which means it should work well with a 5V arduino.

VGS(th) VDS = VGS, 4.5 V

See suggested scheme below.
MOS_FET
ref: © groundFungus

I'd focus more on this;
IXTA60N10T

image

and look to dissipate 4 to 5 watts.

I'd also want to arrange the circuit such that, if the Arduino failed, the heater would be off.

Actually, the maximum is 40mA. People often suggest 20mA to ensure that your Arduino has a long life.

Thanks for your quick reply!

I will follow your schematic, but with another transistor that i found to be cheaper (less delivery costs in France) : https://www.farnell.com/datasheets/2616977.pdf

could you please indicate a suitable diode (D1) reference for this voltage and current ? I guess this is more useful for inductive loads than resistive load, but use it anyway?

thanks again !

Hello 6v6GT, can you please elaborate a bit on how to design the Arduino circuit so that if it fails, the heater is turned off ?

I will implement at software level, that in case of errors on temperature senor, the heater will be off. but on hardware level, I don't really see what I can do more?

Looking forward to your reply!
Thanks.

Hi,
Look closer;


The parameter is Vgs(threshold) = 4.5V
That is when the gate starts to get the MOSFET to conduct, NOT FULLY conduct.
IXTP60N10T is not a logic level MOSFET.

Tom... :grinning: :+1: :coffee: :australia:

Probably like this using an opto coupler as a level shifter:

Indeed it is not. The highlighted RDS(on) quoted at no lower than 10 volts makes that clear.

This looks OK as well:

PSMN018-100PSF

At 15 Amps, expect again a dissipation of around 5 watts.

EDIT

But don't ignore the absolute maximum ratings on the data sheet.

Thank you to all for your advice : i learned a lot on reading transistor data sheets!

  • using opto-coupler to separate arduino from the rest : found this one : https://www.farnell.com/datasheets/91015.pdf

  • Rds(on) is usefull to calculate power dissipation in the transitor :
    P=Rds(on)* I²
    5Watts would need a heatsink to dissipate properly i guess.

  • Pay attention to supply enough Voltage to the gate to exceed Vgs(th) in order to fully "open" the transistor

  • pay attention to supply enough current to the gate so it charges up correctly (Igss) (seems to be no issue when values are below 20mA for arduino, but this does not matter when using an optocoupler that has it's own power supply for the emmitter

  • pay attention to the absolute maximum ratings : Idrain (max) : which is 53Amp for the https://www.farnell.com/datasheets/2616977.pdf at 10Volts,

Thanks again everyone.

Which Arduino?
How about a logic level MOSFET like:
Logic Level MOSFET

But since it is again, not a logic-level FET, then it is only usable with your optocoupler circuit.

Not more useful, only required for an inductive load. Meaningless for a resistive load. :sunglasses:

Looong heating wire is not inductive?

That will depend on whether the wires run together as a pair, or around on opposite sides of the room. :grin:

Are they wound around an iron or ferrite core?

The Mosfet: IRLB3034PbF mentioned in post #12 looks good for direct drive by a 5 volt Arduino pin and has a very low RDS(on), quoted at 4.5 volts, of 1.7mOhms. This should dissipate less than 0.5 watts at 15 amps. You can then use a simple circuit similar to the one in post #2

Having said that, if you get a mosfet with a higher RDS(on), you may not need so much heating wire because the mosfet itself should get hot enough for most purposes.

Hello Everyone,

@JCA34F
I Will start with an arduino nano, but at some point i would also like to add connectivity thanks to a Wemos D1 or similar ESP8266, where the logic levels are only 3.3V so i think to go ahead with an optocoupler before the transistor, good idea ?

@6v6gt
Thanks for the additional info !

Regarding the logic level FET's like IRLB3034PbF, : no need for a heatsink if only dissipating 0.5Watt at 15Amp ?

The IRLB3034PbF comes at around 5€, I found a similar cheaper one https://www.farnell.com/datasheets/1915990.pdf ,
seems to be sufficient , and costs half :slight_smile: what do you think ?

Finally, do you know which Diode I can use for this setup (if driving an inductive load like an servo valve or a motor) at 12 V, and from 1A to 15Amp

looking froward to complete the project :slight_smile:

Cheers!

The IRFB7437PbF is similar to the IRLB3034PbF but, in exactly the area important for your application, not good enough. Look at the voltage at which the RDS(on) is quoted. It is 6 volts. Don’t even imagine some sort of linear interpolation between this 6 volts and the 5 volts you can drive it at directly with an Arduino of the Uno/Nano caliber. That resistance is critical to you. Every 4 mOhms means another watt to dissipate. If, however, you use the opto coupler circuit which effectively delivers 12volts to the mosfet gate, there is no problem with any of the mosfet options so far seen in that they are all within in specification but still go for the lowest resistance ones to avoid heat generation.

As for the diode, I guess a 1n4007 would be OK.

The rule for the "commutation diode" or whatever term you use, is that it is rated for at least the current drawn by the load and at least the voltage applied to the load. No more (is needed), and no less.