I set up an arduino with thefollowing code built a protoboard out with a 1Mohm potentionmeter
and some resistors and an n-fet. the n-fet is specced at 60v3amp i was figuring that at 12v~17 would be
ok for it with a heat sink. This is the first thing I have tried to do with big motor And it's failed. The thing
that happened is the motor just whined or "ringed". I thought about that and i believe that i need to
expand the the wave form by putting setting the pin high for a loned duration than the analog pwm
function does it for. Something like HIGH; Delay(Wiper / 50); Low. Something like that.
I believe that what is happening is using the pwm function the field doesn't enough time to build
and collapses basically instanly and at higher frequency it whines or rings like I hear.
Please excuse me if my assumptions are wrong or whatnot. I am not and EE I'm a carpenter who
grew up with a total love for computers, programming and electronics.
/* Wrote this to control my ac blower fan. The fan is currently
controlled by a five position switch. I have had hanesses and
connectors melted and catching on fire due to faulty wiring/
cheap, poor connectors. This is a known issue with Chevy Colorados
and continues to be an issue for me despite four replacements of
harness and resistor packs, and a replacement of the blower motor.
I'm over it chevy contracted to parts to a crappy company and I
be putting their garbage in my truck any more. */
int motorFet = 3; //The pin the motors n-fet is controlled by.
int motorSpeed = 0; //Current Motor speed.
int wiper = A0; //Position of 1Mohm Potentiometer.
int oldMotorSpeed = 0; //Really new motor speed but what ever.
void setup() {
pinMode(motorFet, OUTPUT); //Set motor fet pin as output
analogRead(wiper); //read position of potentiometer
// Serial.begin(9600); //used for watching that expected things happen
}
void loop() {
analogWrite(motorFet, motorSpeed); //set pulse width for motor speed
if (oldMotorSpeed < 35) { //cut off point to kill motor like having dial on 0
motorSpeed = 0;
} else if (oldMotorSpeed > motorSpeed + 5 || oldMotorSpeed < motorSpeed - 5)
{
motorSpeed = oldMotorSpeed;
//Serial.println(motorSpeed); //used for watching that expectedthings happen
}
oldMotorSpeed = analogRead(wiper) / 4; //read wiper position and make analog value
}
Post your schematic and we'll discuss the circuit. You realize that you don't need a uController to test you circuit. All you need is a switch.
If it doesn't work without Pwm it is not going to work with PWM.
I would suggest you don't do anything (that means don't touch it) , until we have had a chance to look at your circuit schematic. Draw the schematic on a piece of printer paper, take a photo and post it. The most important thing we need is the electrical specs for the system
(wattage, voltage, current, anything you can get).
What information did you use to choose the following device ?
MOSFETs are chosen by voltage and on-resistance, ignore the current rating and calculate the
dissipation from the actual load current and on-resistance - if thats more than your MOSFET/heatsink
combination can deal with its the wrong device.
A MOSFET driven from 5V must be logic-level, most MOSFETs require 10V of gate drive.
Both posts great questions.
The motor is really an unknown quantity. I've looked it up but can't get details. I know its 12v the switch goes to ground with 1 watt resistors and a larger than I can find at radio shack diode pointed towards the full ground pin on the resistor pack. Don't know the resistor values because unfortunately the pack has melted down again. I do know the fuse is 30amps but I know that's way above the actual load of the motor. From what I can gather nominal max is 6amps @ 12V. I was trying to just get it going and figured that as a permenent way to do it I would go with 2 of of those n-fets and phase them 180° apart so they could share the load.
As for the circuit I have that at home but the n-fet I was trying to use was an irf510 to220 60v 3amp max which I figured would be OK at 12v6amps with a standard to220 heatsink. The get never overheated and failed but the motor never spun either. The whine came from the motor certainly. I used a 10kohm pulldown resistor on the gate pin for the n-fet. And a 10kohm pulldown between the the ground and the A0 pin for the potentiometer.
I'll have to be home to get the circuit diagram. I'm working away fromfrom home during the week. I figured I'd ask now so maybe I have an idea of what to try to do this weekend.
I really think the pulse rate is too high. This circuit worked on a 3watt led with the n-fet acting as a ground switch and the potentiometer was dimming it and shutting it off as expected.
The whine or ringing I heard from that motor really makes me think it was just switching too fast for the field to build.
I had a similar problem with a 3hp 3phase motor being driven by a vfd that I purchased until I was able to understand the Chinese to English translated manual and figured out that the factory pulse rate was too high. Once I figured out how to change that and get it working I had, still have, a wicked strong wood working lathe with push button variable speed. Next thing is to put a pot and e-stop on it.
Thanks for your time and patience with me because I know I'm a neophyte with this stuff and I'm not giving a totally clear and concise picture of what's happening.
Great point about the n-fet on both posts I'll figure out what the switching level is on it and also try to see if I can turn it on with a steady solid voltage and make the fan spin.
We need a schematic. Something is definitely wrong but I don' t think any of this talk is getting us closer to the solution. I think we need a schematic and some hard facts . The absence of current measurements or motor winding resistance measurements or any model # or part number is really hindering the troubleshooting process. We neee some hard facts; a part number or some measurements. I don' t see any point in discussing software with a motor that doesn' t turn. Can you or can you not draw a schematic on a piece of paper , take a photo and post it ? (Is there anything preventing you from doing this ?)
Can you measure the motor winding resistance ? (I didn't see any reason why not in your previous comment )
Can you measure the current ? (same comment)
Can you measure the resistor pack resistance ? (Why does it being melted prevent you from measuring it ?)
Can you test the Mosfet with a meter on diode scale ? (couldn't see any reason why not)
These are the things that need to be done to move forward.
do it I would go with 2 of of those n-fets and phase them 180° apart so they could share the load
What does that mean 180 degrees apart ? Can you draw a schematic of what you mean ?
As for the circuit I have that at home but the n-fet I was trying to use was an irf510 to220 60v 3amp max which I figured would be OK at 12v6amps with a standard to220 heatsink.
If the blower is fused at 30A , even if the motor max current was only 20A (40 % less), that would still be 17A more that your 3A fet could handle. I don't want you to get offended but are you guessing on everything or is any of your plan based on any facts ?
This is a fair and reasonable question isn't it ? (given that we haven't seen any facts yet) . Is it not possible to look up the schematic for the vehicle online ?
MOSFET current ratings are usually thermal limits at exrteme conditions (infinite
heatsink, maximum working temperature).
A 3A MOSFET would rarely actually be used above 1A, and for switching 10A a 100A
MOSFET would often be chosen so that heatsinking is minimal.
The IRF510 is wholely inappropriate for your application as is has an on-resistance
of ~0.5 ohm and is not logic-level. Something logic level and nearer 0.01 ohm would
be a good starting point for devices to consider. BTW the IRF510 is rated at 5.6A, not 3A,
and 100V, not 60V, so have you got the right part number?
If you measure the resistance of the motor with a multimeter you'll be able to estimate
the stall current rating.
Sorry each don't mean to frustrate but like I said I'm not home I work away from home during the week so I can't provide a schematic at the moment but I will. I have one sitting on my desk with a soldering iron burn on it and all.
I do have a radio shack across the street and I bought an arduino and one of those MOSFETs on the way back to the room the model is irf510 and the max limits printed on the bag are 60v3amp. I was going to try it with setting the pin high but if it won't work anyways I'll just wait til Friday when I get home.
As for the motor I can find the part online at many different e-tailers but I can't find any hard specs on it. I have found some hints on forums for this particular truck but I haven't been able to find a data sheet on it.
Don't have a meter with me because for work I am a Carpenter and I didn't think to bring it because I'm so beat after work I don't have the energy to focus on this stuff.
Been reading alot more over the past few days about mosfets. interesting things they are.
Looks like there are 169Amp TO220 ones designed specifically for my application in the IRF
family.
another interesting thing I read is that unlike transistors they share loads better. As one
warms up it resists more allowing the next to breakdown and start taking on some load.
I understand that that is suboptimal, but they seem easier to manipulate into more even
load balancing than transistors and they handle higher loads.
so heres the idea now. I've ordered those 169Amp ones, 20 of them for future use and
experimenting. I'm thinking of heatsinking two of them onto a small copper block and
using that as my output as well since the tab is both heatsink and load. This will allow
load sharing. Then putting a .1mohm resistor on the gate pins for each one and then using
one pwm pin to switch them on and off. Thats the idea at the moment until they arrive.
To address the questions about the motor. I have no solid info I have found the wiring
schematics previously but they don't tell me what the specific for the motor are and I
still can't find a data sheet on it.
as for 180 degrees apart. i was thinking I could make two of them run at only half demand.
but have them serialized so that as one turns off the other turns on. So say there is 50%
demand one would be on for 25% then the other for 25%. I've abandoned that based on the
169Amp mosfets that I found and am awaiting delivery for.
I think I have it figured out. However if anyone has any input that could be useful I am all
ears.
There is no picture attached. Use "Additional Options " button below to add attachements.
as for 180 degrees apart. i was thinking I could make two of them run at only half demand.
but have them serialized so that as one turns off the other turns on. So say there is 50%
demand one would be on for 25% then the other for 25%. I've abandoned that based on the
169Amp mosfets that I found and am awaiting delivery for.
That may be how you think of it but describing it that way only confuses things. The use of the term "180 degrees apart" does not apply to complimentary or push-pull or inverted phase driving of power devices unless it is a bi-polar power supply .. What you are saying is not what you mean. Loose the "180 degrees " part unless your talking about a bi-polar power supply driven circuit with either + and - voltage supplies with some devices driving the positive phase and others driving the negative phase. There are many types of power circuits that use this positive & negative supply arrangement. Audio amplifiers is one . There are some motor drivers that use that . The same applies to an AC circuit where there are devices turning on during the positive phase and other during the negative phase. Your blower runs of a single rail with a voltage of +12V so the term 180 degrees apart has no meaning here. What you are describing is parallel devices with some driven by the inverted
signal of others, so when half of them are off , the other half are on. The only problem with that idea is the in order for the PWM to be correct, when it is LOW, everything should be OFF. When it is HIGH, everything should be ON. The power to the load is controlled by the duty cycle of the signal. If you are not an electronics technician or engineer with formal training, do your self a favor and stop thinking up ideas that are have no basis in research. Paralleled fets or mosfets is a widely used practice and usually involves devices with low on resistance. I realize your intention is good but you really shouldn't be coming up with these ideas. You should be researching on the web and posting documentation or code or schematics that support your idea, OR asking us what we think. If you have no electronics background, learning it by trial and error could have negative consequences. Not to exaggerate but I am reffering to something like hacking your truck blower circuit and having it catch fire while you are doing 70 mph on the freway with all that air coming in the front grill. It could turn you truck into a rolling blowtorch. If you were working with AC circuits I would say experimenting with no formal training or electronics experience could get you or someone else killed. In short. don't ever power up a circuit that you don't have any documentation to support. Get a second opinion first. I don't want to scare you but I'll tell you a little story. I was working in a lab one day and some guy had a little tiny 2n2222 transistor on a circuit. Now if you have ANY electronics experience WHATSOEVER , even the
tinyest bit, you MUST know immediately that it a little 3-pin device that can come in a little plastic package with a flat face and a round shape, like a semicircle . It is nowhere near the size of a TO-220 device. Something happened and there was a loud bang. About 50 to 100 mS after the bang , I could hear what sounded like a BB hitting the wall and the ceiling and then a table top and finally another wall and then landing on the floor. We all went over and looked at the circuit board that still had a little smoke hanging over it and saw a round crater in the face of the transister going all the way to the center of the device. I am not exaggerating one bit when I say that had anyone been in the path of that piece of plastic when it blew, it would not only have gone completely through their eyeball, but it could have gone all the way through their brain an stopped on the inside wall of their skull. If that is not enough to put the fear of God in you I don't know what is. Now imagine that happening with a TO-220 device. Now your are talking about a seriously lethal projectile. If you don't know what your doing , don't do it and if your working around circuits that are new or suspect, wear safety glasses. I am not trying to make you feel bad but this:
as for 180 degrees apart. i was thinking I could make two of them run at only half demand.
but have them serialized so that as one turns off the other turns on. So say there is 50%
demand one would be on for 25% then the other for 25%
Sounds to me like you are just making this up as you go along. If you are going to experiment, take precautions. Keep a fire extinquisher in your truck just in case. (you probably already have one after the last fire eh ?) and wear safety glasses.
Btw the Truck did catch on fire with the blower control circuit that comes in it ..
Guess it was designed and well researched by an EE of high calibre.
I am not a complete idiot with electrical and Don't fully appreciate you condescension.
Phasing the fets with pwm is possible. It will be DC not AC and I understand the Differences
between the two. But it is possible the to have one on for half the pulse duration and the other
on for the other half of the pulse duration.They would be sharing the load that way. The picture
was visible for a while from google drive, but here it is uploaded.
As I said before This did work as it was Driving a 3watt LED It faded up and down with the
potentiometer as it was.
Please in the future keep it professional or to yourself dude. I'm not some chump kid of yours.
I'm sorry you were offended. As I stated, in my comment, that was not my intention and I did not discourage you, I advised more research. You put a lot of time into the circuit and stated you had done some research. My concern was that there was no evidence
in that in your post . You did not post any schematics of motor driver circuits , such as the one I attached. Moreover , your drawing
hardly resembles a schematic. You diode appears to be backwards. The cathode should be at the positive terminal of the motor, not the negative terminal that connects to the mosfet drain. (see the attached schematic). I'm not going to comment on your code, although I would like to. My comments were solely based on the absence of any research documents or schematics in any of your posts that would indicate you have spent time with Google researching your topic. If you were offended, so be it. Post something that resembles a schematic
FYI,
resistors that are terminated at ground are usually shown vertical , not horizontal. The only exception is when the schematic is so cluttered that there is no room to show it in the vertical position. If for any reason it must be shown in the horizontal position,
the ground symbol is still represented vertically with the ground symbol toward the bottom of the page and the connection going up (and over if necessary). The ground symbol is never represented horizontally as you have represented in your illustration, which I prefer not to call a schematic.
I am a Hobby EE but a career Carpenter so far.
I think you need to learn how to draw a schematic before you can call yourself an "EE" , hobby or otherwise.
I call em like I see em. I don't see any research done on your part and that is what prompted my comments.
As far as your code is concerned, you might want to add comments for this part of it explaing your critera or objective with
these conditional statements so anyone else reading it will understand what your "target range" is . There is nothing in your
post explaining what part or parts of the 0 to 255 PWM range you are trying to use , and which part you are trying to avoid.
This decision making can also be done with CASE statements.
if (oldMotorSpeed < 35) { //cut off point to kill motor like having dial on 0
motorSpeed = 0;
} else if (oldMotorSpeed > motorSpeed + 5 || oldMotorSpeed < motorSpeed - 5)
{
motorSpeed = oldMotorSpeed;
This will be my last comment on this thread. Good luck.
I looked at your code and discovered your analogRead of the wiper was in the void setup() which means it is only executed ONCE.
I moved it to the loop and changed your code to this which works fine.
/* Wrote this to control my ac blower fan. The fan is currently
controlled by a five position switch. I have had hanesses and
connectors melted and catching on fire due to faulty wiring/
cheap, poor connectors. This is a known issue with Chevy Colorados
and continues to be an issue for me despite four replacements of
harness and resistor packs, and a replacement of the blower motor.
I'm over it chevy contracted to parts to a crappy company and I
be putting their garbage in my truck any more. */
int motorFet = 3; //The pin the motors n-fet is controlled by.
int motorSpeed = 0; //Current Motor speed.
int wiper = A0; //Position of 1Mohm Potentiometer.
int oldMotorSpeed = 0; //Really new motor speed but what ever.
void setup()
{
pinMode(motorFet, OUTPUT); //Set motor fet pin as output
Serial.begin(9600); //used for watching that expected things happen
}
void loop()
{
int val=analogRead(wiper); //read position of potentiometer
motorSpeed=map(val,0,1023,0,255);
analogWrite(motorFet,motorSpeed );
Serial.println(motorSpeed); //used for watching that expected things happen
delay(100);
}
I can see how a viewpoint can be had that someone didn't do any research and is just fishing for someone to do it for them.
I'm certainly not that guy. I guess without asking for it I was expecting the benefit of the doubt. When I say I've done something I've done it. I breadboarded the circuit ran the code and dimmed a 3watt led with it as is stands. I make a rough sketch of a circuit and code just to kind of flow chart. Then my empirical self kicks in and I have to put paper into the real worlds.
I can say that the circuit and code as shown did work as expected. It didn't need those modifications but I do appreciate the slimmed down code and alternative methodology. Hadn't seen that map function , or at least not in a way that made a lot of practical sense to me. But now I see it clearly.
So for the MOSFETs I'm looking at different ones in the 55v-100v range from 26-202amps.
Maybe I have a fundamental flaw in my understanding of this part of electrical theory.
VA=W so 55220=11110 watts peak delivery. I understand that it isn't really practically possible to use one at peak for any period of time without magic smoke. In reading I have found that for heat dissipation I should really only demand 10-20% of peak possible current or I will be needing some serious heat sinking.
Maybe this is where my fundamental failure of understanding lies. 11110 watts / 12 volts = 925Amps . I believe that would be more than suffice for the application I have in mind. Maybe its not that simple to convert power output on these things between different voltages. If not then why not?
One thing I see on the data sheets is the vgson. Not sure exactly what that means but from what I can gather that is the voltage differential between the source and gate. Also from what I can gather that is the limit of diffence between the two pins before the gate won't close and allow current flow. So running at 12v and switching at 5v is within 20v Only a 7v differential so I can't see how that wouldn't work . but again maybe there is something that I'm not understanding. If so please explain.
I want to know this stuff and understand it. Just for the sake of knowing and understanding for doing things with stuff that I think is cool.
Unfortunately, it seems to be hard to find a decent tutorial on Mosfets but I will try to cover the most important factors.
1- RDSON = This is the internal resistance. When VGSON is met , (VGS = VGSON, that means VGS > VGSTh , which is the Treshold voltage at which the mosfet begins to conduct. When it is in the ON state (above threshold) , it acts like a resistor, and the RDS varies with the amount of current and the VGS voltage.. If you look at page 3 of attached datasheet for a Logic Level Mosfet (which is all I use with the arduino) you will see that at 30 A , the Drain-Source voltage is 3V. If you look at page 4, you will see the Drain -Source Current is 60 A when the Gate-Source voltage is only 4.5V. That means that the output pin of an arduino in HIGH state will drive this mosfet to 60A. The RDS = 0.047 ohms, (47 mohms). At 60 A , power dissipation is 96W , which makes this device very efficient because if you do the math, 30 A @ 60V = 1800 W so POUT/PIN = 1800/1896= 95 % efficient. It is a TO-220 case and since
your heatsink needs to dissipate 96W you need a good TO-220 heatsink, not one of the those 15 cent ones. You need one like this:
If you go back and read all your posts in this thread, (Original +Replies #3,6,7,10, & 13) you will see you have providing nothing for us to research your choice of fet. In the electronics world , it is not enough to say you are using a device that does this or that, because the standard response is "show me your data ." (datasheet, or part number for a search , or link to the datasheet)., none of which you have done, so we have no idea what your VGSON voltage is for your 169 A mosfets. We can assume that they are NOT Logic Level simply because you did not state that. If you had ordered Logic Level Mosfets, you would have wanted us to know that you knew that was what you needed to control a mosfet from an arduino . Now we will have to wait and see if your devices will require external drive circuitry to boost your arduino 5V to +15V to get the drive you need, since most mosfet are turned ON with +15V and OFF with -15V (which you don't have), hence the advantage of Logic Level (0 to +5Vdc) mosfets. Since we (I) can't discuss the performance parameters of your devices, I will stick to the ones I use.
Basically, in a nutshell, you just need to make sure that VGSON is < VTh and VGSOFF is < VTh..
Another very interesting parameter is Peak Current Capability (A) vs Pulse Width (S) on page 3. It shows that the device can
conduct 400 A if the pulse width is 1 uS , but only 30 A if the pulse width is 1 S.
How can you use this information ? Well, one thing it would suggest is that multiple devices in parallel driven by a low PWM duty cycle could conduct a lot of current for very brief periods. The value of this depends on the load , since if you are driving a light emitting device where human perception comes into play, the POV factor (Persistence of Vision) would mean that a person's eye
would retain the image for some uS or mS even while the device is off. If the load is driving sound (such as a speaker or horn), once the sound wave is initiated, it will continue to push the air as it travels to dissipation so a brief pulse of a speaker or horn could generate some sound that would be heard AFTER the device has turned off due to the speed of sound delay. If the load is inductive, a solenoid or actuator or motor could begin to move with a brief pulse but it would have to be more that 1 uS. As you know, an object in motion tends to stay in motion so this means that multiple parallel devices could drive a motor even at a low duty cycle solely due to momenum..
What you should take away from this post is never talk about semiconductor devices without presenting your data.
That is rule #1.
Never order semiconductor devices without fully understanding the parameters on the datasheet.
That is rule #2.
Never apply power to a circuit until your have done two things:
1- checked the wiring against the circuit schematic or wiring list. (your circuit is simple enough I think we can skip this for now)
2- crunched the numbers to make sure your driving devices can support your load. In your case, since you are using a 105 mm Howizter to kill a fly, I think we can skip this step.
I am still curious about the polarity of the diode. As you can see from the schematic I found on the web, the cathode should be connected to your +12V supply and the anode should be connected to the drain of the Mosfet. I don't know how your circuit could work.
Why are you interested in the 169 A mosfets when you have already stated the blower is fused for 30A. Are you planning on using them for a different project ?
Is the motor in your truck REALLY connected to +12V with one lead and then switched to ground by PWM?
Most Auto Fan Motors have one lead inherently connected to GROUND and you then have to PWM the 12V lead.
If this is the case, your easiest bet is to use a P-Channel FET to switch the high side.
Most certainly Ground switched. there is a resistor pack in the main blower switcher assembly. This pack resists to ground with 3 I believe 1watt resistors a bypass and a thermo fuse from what I can gather. The Dealer and Parts Stores replacements are glopped over with some sort of epoxy so I can't put eyes on the resistors.
Speed four goes on the bypass to ground directly for full speed, I have done probing with a volt/ohmmeter and jumped this connection to a good ground, it is confirmed. speed three goes through one of the resistors. Speed two goes through one of the other resistors. speed one goes through the speed two resistor and the last one.
I have found and re-engineered the ground points throughout the truck. I cut the wires, stripped, and soldered them to ring terminals. I then sanded the paint off of the ground bolt points and tinned the metal. Then I bolted the ring terminals down and heated them up to sweat the ring terminals to the body and covered it all up with thick layers of liquid electrical tape.
The above was the root cause of the melted light bulb(turn signals) sockets and melted Blower fan stuff. I could just put the stock parts back in and have it working as good as new again. I'm more interested in doing something different though.
I appreciate you point of view Rasch. and all .
I would really like to know if my understanding of electrical fundamentals applies to these mosfets.
IE. 40V@202A max theoretical power handling = 8080Watts
so 12v@8080Watts = 673.3333Amps max theoretical power handling
^^^^^^^^^^^^^ Is that right do these principals apply to MOSFETs like they do to wrapped wire transformers?
That would be extremely helpful to know.
Also that VGS being +-20V means to me that as long as I'm within 20V of the system/line/supply voltage I want to switch I
should be able to switch the MOSFET on and off. With a RDS(on) of .004Ohm it should be 5V logic
switchable on a 12V system.
^^^^^^^^^^^^^^Is that right?
Haven't gotten the Things in the mail yet.
Actually ordered 10 of each IRF1404 and IRF1405
From this place IRF MOSFET Power Transistors
1404 Direct to Data Sheet IRF1404 Datasheet
1405 Direct to Data Sheethttp://www.futurlec.com/Transistors/IRF1405.shtml
Work is about to pick up To 12hours/day 7days a week so I'll be putting this on hold for
a bit. probably a month or so then of to Singapore for work for a month then I'll probably be able to pick this back up.
IE. 40V@202A max theoretical power handling = 8080Watts (this is the mosfet rating: P (W) = I*V)
Since the power rating of the mosfets is
so 12v@8080Watts = 673.3333Amps max theoretical power handling
This is true but you have to realize the current drawn is always determined by the load. Also , the rating assumes good heatisinking.
There is nothing in a vehicle that is going to draw 673 A . I don't even think the starter motor draws that.
Where :
V=12V
I = 673 A
P = 8080 W
The rating of the mosfets at 12V may not be the rating at 40V. You need to refer to the graphs in the data sheet.
Since it is a curve, it is likely the there is a different rating at 12V.
In general you math is correct but without looking at the graphs on the datasheet your conclusions could be inaccurate.
Fig.-1 on page 3 appears to show 500 A @ 12V., (not 673 A) You can check it for yourself.
fig-3 on page 3 appears to show the D-S current to be about 50 A with 5V Gate-S voltage. I don't know how the fact that it is on a 12V system has any relevance to the drain source current with 5V on the gate. If you can explain what you mean by that we can comment on it, otherwise , as I said , it is irrelevant.
raschemmel: Fig.-1 on page 3 appears to show 500 A @ 12V., (not 673 A) You can check it for yourself.
That should work for my blower fan and stay pretty cool too right? using a max , based on installed fuse, of 16.6667% of the
mosfets peak power handling at 12V. That puts it in the cool as a cucumber range right?
Should I maybe consider running two in parallel with a heatsink just to make sure there is some surge current handling capacity?
Now the other question is with the Gate. That should be logic switchable at 5v with a +-20v Vgs(on) and .004Ohm Rds(on) right?
If I'm missing some fundamental with the above please point it out. and if you have before I'm sorry but I didn't understand the information relayed.
