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Author Topic: Suggestion for SMD N and P channel Mosfets ~12V / 10A  (Read 1688 times)

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Offline TrickyNekroTopic starter

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Suggestion for SMD N and P channel Mosfets ~12V / 10A
« on: June 26, 2010, 01:05:51 PM »
As the title simply suggests I need some good suggestions for SMD Mosfets...

Both N channel and P channel needed, I'm building a H bridge...
I not really a fan of IC either....
Simple things ;-)

So any tried suggestion??? I need SMD parts...

Thanks in advance, Lefteris
Greece
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P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

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Offline klims

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Re: Suggestion for SMD N and P channel Mosfets ~12V / 10A
« Reply #1 on: June 26, 2010, 08:25:28 PM »
Look at something called an 'external turbo' for mini rc cars. I designed and built one myself a little while ago now.
There are a few different SO-8 package mosfets used, some more exotic and harder to get than others.

There aren't many (if any) SMD mosfets that can handle 12V/10A constant so what people do is stack the mosfets to run them in parallel. Works fine till you get to about 4 or 5 high where you start to lose responsiveness, although I'm not sure if this was due to the limitation of the RC car or something else.

Offline TrickyNekroTopic starter

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Re: Suggestion for SMD N and P channel Mosfets ~12V / 10A
« Reply #2 on: June 27, 2010, 10:47:26 AM »
Basically if should be from the receiver not being able to drive so many mosfets....
But that's another case...

I'll definitely look at it!!! Thanks!!!
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

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Offline Soeren

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Re: Suggestion for SMD N and P channel Mosfets ~12V / 10A
« Reply #3 on: June 27, 2010, 10:56:28 AM »
Hi,

There is a plethora of SMD MOSFETs at this low current  ;)
I prefer to go a little higher than needed currentvise, without overdoing it, as it's usually a tradeoff between I_d and C_iss.
 
40V/17A/N+P
http://www.fairchildsemi.com/pf/FD/FDD8426H.html

40V/20A/N+P
http://www.fairchildsemi.com/pf/FD/FDD8424H.html

In SO package
http://www.fairchildsemi.com/pf/FD/FDS4465.html
http://www.fairchildsemi.com/pf/FD/FDS6670A.html
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
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Offline klims

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Re: Suggestion for SMD N and P channel Mosfets ~12V / 10A
« Reply #4 on: June 27, 2010, 02:46:44 PM »
Also not sure if you know this, but p-chan MOSFETs need the same gate voltage as the input voltage: ie if you are driving motors at 12v your logic needs to be 12v. You will need MOSFET drivers to do this.

Offline TrickyNekroTopic starter

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Re: Suggestion for SMD N and P channel Mosfets ~12V / 10A
« Reply #5 on: June 27, 2010, 02:50:44 PM »
Hey Soeren thanks for the reply...

Yeah, I know... I just don't like the idea of having a failure board again....
Plus this time, I'm doing a 250$ order on raw parts, and these days money don't come that easy...
I'll shall hit of course the local supplier before buying anything from the net...  ;) I get a nice nice discount...

Thanks for the information!!! I had the first two in mind two... but unfortunately mouser doesn't stock them...
And a lead time of 14 weeks if far long for the project goal time.... :-/

I'm thinking of getting some of these SO8... Still.... I'm just kinda worries cause these would overheat faster due to higher on resistance....

Also I just check that the peak current of the motor (stall current) should be around 12 - 13A...
On a not fully charged battery the stall current was around 11 - 11,5A... So I pretty much guess here...
Also I don't really want to go dual cause of the theoretical need of resistors... (Yes with any kinda diode you should place them in series cause of the difference of the junction temperature than may occur and totally screw the poor mosfet)...

Of what if we play with some higher amperage... I'm asking not because I can't search, but because I don't want to get
burnt  :P

Best regards, Lefteris
Greece
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

Cheers!

Offline TrickyNekroTopic starter

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Re: Suggestion for SMD N and P channel Mosfets ~12V / 10A
« Reply #6 on: June 27, 2010, 02:53:09 PM »
Also not sure if you know this, but p-chan MOSFETs need the same gate voltage as the input voltage: ie if you are driving motors at 12v your logic needs to be 12v. You will need MOSFET drivers to do this.

You probably mean simple general purpose switching transistors... Yup, I got that handled...

BC856 and BC846 behave themselves well, tested ;-)

Thanks for the tip anyways :-D

Lefteris, Greece
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

Cheers!

Offline Soeren

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Re: Suggestion for SMD N and P channel Mosfets ~12V / 10A
« Reply #7 on: June 27, 2010, 04:53:40 PM »
Hi,

Also not sure if you know this, but p-chan MOSFETs need the same gate voltage as the input voltage: ie if you are driving motors at 12v your logic needs to be 12v. You will need MOSFET drivers to do this.
A P-ch. MOSFET can be driven by pulling its gate to ground by eg. a NPN BjT, no need for 12V logic - let's not overcomplicate it please.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

 


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