H BRIDGE, driver for a dc motor

[nuttaphong191]

i am designing a 6 amps h bridge bidirectional dc motor driver ckt.

the current rating is 4amps @ 12v..

i m using a pmos on top and nmos on bottom.

the prob is that the upper pmos is getting hot like anything.
i used a transisitor to drive the upper mosfet and a logic level +5v for the lower one.
i even tried connecting one cap(i microfarad) and one resistor(one kiloohm) b/w
gate and gnd,but in vain.

can anyone suggest some tested soln to this prob please...

 

[audioguru]

This is your 3rd website.
I answered you on your first website where you have the same question.

You forgot to attach your schematic on all of them.

 

[Optikon]

i am designing a 6 amps h bridge bidirectional dc motor driver ckt.

the current rating is 4amps @ 12v..

i m using a pmos on top and nmos on bottom.

the prob is that the upper pmos is getting hot like anything.
i used a transisitor to drive the upper mosfet and a logic level +5v for the lower one.
i even tried connecting one cap(i microfarad) and one resistor(one kiloohm) b/w
gate and gnd,but in vain.

can anyone suggest some tested soln to this prob please...

What PMOS FET are you using? How do we know that you havn't grossly undersized its package? How hot it gets will depend on your power losses in the device. They might be large. In any case, at your levels, you likely need to mount device on heatsink.

 

[Hero999]

This is your 3rd website.
I answered you on your first website where you have the same question.

Wow audioguru!

How many electronics sites do you normally visit in a day?

 

[audioguru]

I visit 4 electronic chat sites a few times a day. Many have the same noobies posting the same questions.

 

[blueroomelectronics]

I visit 4 electronic chat sites a few times a day. Many have the same noobies posting the same questions.

What are the other three?

 

[bananasiong]

What are the other three?

audioguru has told before, hasn't him?

 

[Gayan Soyza]

I met Audioguru in electronics lab site one time in that site also i saw he has over 8000 posts.

 

[bananasiong]

Just search:
https://www.google.com/search?hl=en&q=audioguru

 

[audioguru]

There are many AUDIOGURU people listed in Google. Only one is me and you have to guess which one I am.
Sometimes I have to guess which one I am.

 

[blueroomelectronics]

Ah yes Electronic Labs, I was there for a short while. I think Audioguru just likes debating with noobs who will not follow sound advice.

The place was chock full of often bad advice or simply wrong. Audioguru would attempt to fix and get often bizzare responses.

I could only take so much of it.

Lets see another fun forum is EDAboard, seems all those folks want is...

1. free books from rapidshare
2. do my homework for me
3. extemly vague questions expecting a detailed response
4. fix my unreadable code
5. build an ICD2 (good place for info on those acutally)
6. build a moving LED sign badly.

My personal #1 favourite goes like this

"My code / circuit isn't working, plz advize how 2 fix it"

That's it and when asked for code or circuit, nada. Or they post a small out of context fragment of no use to anyone. As if their top secret design has would be stolen by all.

And here's a link for all those students on finals who slept through class and want the forums to do their homework.
http://icanhascheezburger.com/

EDIT just in, I did a google for audioguru and got these forums... BUT THE BEST PART IS

MSTECHCA


was the first hit!
All must bow to MSTECHCA the master of bad design and misinformation.

JUST IN! Google MSTECHA and got this as hit #1
http://profile.myspace.com/index.cfm?fuseaction=user.viewprofile&friendid=88268775

Oh the horror.

LOL forgot the C.

 

[audioguru]

The big American woman called MSTECHA is not the misinformed Canadian guy called MSTECHCA.

I always laugh when the billions of noobies from India address us as SIR.

 

[blueroomelectronics]

Dear SIR, I would like to build a biometric retina scanner for a door lock. I am not familiar with electronics but I think this would make a good final term project.
Would you please post a retina scanner schematic and all code required. I have access to circa 1970 electronic parts pulled from old washing machines.
URGENT, need it in two day.
Thank you.

Now repeat this in EVERY forum.

 

[audioguru]

These worldwide forums are very confusing. Many people can't find the parts in their market (food market?) to make something so ask for substitutes but we don't know what they have available.
Some people talk about vacuum tubes and others talk about valves.
Some people weigh their money in pounds, while others use grams and dollars.
Inches or centimeters. Driving on the "wrong" side of the road or on the right side. Some people are addressed as SIR while others are called MATE.

Then we get noobies who come here to learn English instead of Electronics.

 

[Styx]

anyway back to the question at hand... if you are driving with 5V then you are not turning the FET's off and hence why they are getting hot

 

[bananasiong]

The big American woman called MSTECHA is not the misinformed Canadian guy called MSTECHCA.

She is 31

I always laugh when the billions of noobies from India address us as SIR.

Isn't SIR the title of respect for a guy? Any other meaning?

 

[audioguru]

Nobody is addressed as SIR in Canada for about 50 years. Now, most respect is given by actions, not by words. I might address the king of a big country by SIR.

I think 50 years ago important people were addressed by SIR here.

 

[bananasiong]

We address our male lecturer as SIR, but not Mr. (surname)..

 

[Nigel Goodwin]

We address our male lecturer as SIR, but not Mr. (surname)..

It's called 'politeness' - perhaps it's a concept they haven't heard of in Canada and North America?

 

[audioguru]

We are polite in Canada. We don't go around calling people names like many years ago. Exceptions:

1) Judges in a court of law are addressed as 'Your Honour".
2) The Prime Minister might be addressed as 'Your Excellency" or something.

Most people are addressed by their name today.