How does one connect a high current device like a MOSFET to other components? My mosftet is an IRFZ44, and during operation, it will carry about 12 - 15 Amps. (the max current of the device is 55A).
Ordinary strip-boards or breadboards can't handle that much current.. so is direct soldering the only option?
I think yes, direct soldering will be the option for handling this much current. But the other device with which you will be soldering it, will that device be able to handle this much current???? :~
yup.. it's just a solenoid.
I'm still open to more suggestions..
There are several versions of IRFZ44 some have an other letter on the end. The type with no letter on the end is OK to switch with a logic level the others may not be so see your data sheet. However switching so much with a logic level with this FET is probbly not going to work. You should get a true logic level FET.
The maximum current of a FET is not a useful figure you can almost never get anything close to it in practice. This is because the limit is the power dissipation, this kicks in long before the current limit.
As you rightly say you must wire the FET up with suitable gauge wires and not let the current flow through the strip board.
I'm not using a +5 voltage to switch it. In my circuit, the MOSFET it turned on by supplying a +11 Voltage (or +12) to the gate.
I still haven't found out how to connect a high current device like that..
Does anyone know how it's done in cars? (apparently, cars have high current MOSFETs too)
I still haven't found out how to connect a high current device like that.
Do you mean high voltage?
It is normal for FETs to need 10V to turn them on.
Are you saying you want to generate this gate signal from the arduino?
If so:-
One thing I have done is use a small double-sided screw-type terminal strip and connect the 3 FET leads to one side, and on the other to the power supply - and the device, with #14 or so wire. Then a small size wire from power supply - to Arduino Gnd and small wire from (FET driver) to FET gate. The FET can get mounted on a heatsink if necessary.
I have put a large fast-recovery diode in the same terminal strip, and the leads to the device (DC motor in my case) came out of the same terminal strip.
So those connections are all compression in the terminal strip, no soldering of big leads...
YMMV...
Many thanks Terryking.. That's what I was looking for.
Grumpy_Mike:
I still haven't found out how to connect a high current device like that.
Do you mean high voltage?
It is normal for FETs to need 10V to turn them on.
Are you saying you want to generate this gate signal from the arduino?
If so:-
- There is no need if you use the right FET
- You use a transistor to boost the 5V output of the arduino to the higher voltage the FET needs. Arduino output to a 10K resistor, other end of resistor to the transistor base. Emitter to ground, collector to FET gate and 1K resistor. Other end of the 1K resistor to +12V. FET source to ground, FET drain to one end of your load, other end of your load to +12V.
You've misunderstood me. I have build a MOSFET driver and it supplies 12 Volts to the MOSFET, turning it on fully. My problem is that I don't know how to physically connect the MOSFET leads (drain and source) to anything else, since they will be carrying a very high current.
Also, Here's an example of a PC Board designed for high current FETS:
Note the wide circuit traces for the high-current paths. This board also uses (I believe) thicker than usual copper layers.
more about this board here : http://arduino-info.wikispaces.com/Brick-4ChannelPowerFetSwitch
DISCLAIMER: Mentioned stuff from my own shop...
You've misunderstood me..... My problem is that I don't know how to physically connect the MOSFET leads (drain and source) to anything else, since they will be carrying a very high current.
As I said you use wire, the FET and wire go through adjacent holes in the strip board, but instead of letting the copper carry the current you make the wire end a bit longer and wrap it round the FET leg. Then the copper strip just acts as the thing to provide mechanical stability.
Alternatively you use tinned copper wire on the back of the tracks to give them extra current carrying capability. Like this:-
Ok.. Thanks for the info guys.