motor driver (without pre-driver ICs)-possible?

[sjd.aliyan]

I want to use this driver for both servos and steppers.

i think a processor like STM32F3xx or STM32F4xx and couple of logic level mosfets could do this job.
is it possible or i forgot something?

[danadak]

Its a problem because the UP outputs cannot get the charge out of the
motor driver fets fast enough. The result is driver fets spending too much
time in linear region, overheating. Possibly not even getting fets into
saturation. This is all dependent on PWM frequency, thermals, etc..

A good motor driver H bridge has thermal management, gate charge
management, current limiting...Wise to use one.

Infineon, On Semi, TI, ST......

Regards, Dana.

[sjd.aliyan]

Almost all cortex series(A-M) theoretically have up to 24 mhz IO pins.
and new mosfets can be driven at high frequencies.
so i don't see a problem about speed
I agree logic level mosfet have less diversity than normal mosfet so gate driver is necessary .
current limit needs a DAC and a Op-AMP

Pre designed ICs are limitation and they're designed for a specific rules and applications.I prefer to design from scratch.

anyone can help?

[langwadt]

Almost all cortex series(A-M) theoretically have up to 24 mhz IO pins.
and new mosfets can be driven at high frequencies.
so i don't see a problem about speed
I agree logic level mosfet have less diversity than normal mosfet so gate driver is necessary .
current limit needs a DAC and a Op-AMP

Pre designed ICs are limitation and they're designed for a specific rules and applications.I prefer to design from scratch.

anyone can help?

the 24MHz are at no load, there is a reason for the gate drivers that can deliver several amps of current. The gate of a mosfet is basically a big capacitor it takes a lot of current to switch it fast

[danadak]

"Almost all cortex series(A-M) theoretically have up to 24 mhz IO pins.
and new mosfets can be driven at high frequencies."

Yes, at 20 pF Cload, but looking into gate of low Rdson power mosfet
answer is  a problem of large gate charge that has to be removed/added
to effect switching, to avoid spending much time in the linear region, the
miller region. Typical gate drivers handle amperes of current when driving
gates, clearly not ARM I/O pin capable.

http://www.infineon.com/dgdl/mosfet.pdf?fileId=5546d462533600a4015357444e913f4f

https://www.fairchildsemi.com/application-notes/AN/AN-558.pdf

http://www.microsemi.com/document-portal/doc_view/14692-mosfet-tutorial



Regards, Dana.

[sjd.aliyan]

OK,i accept your reasons on gate driver i would use a lm5109,it think it would be good enough it supports current up to 1 amp.

what mosfet do you suggest for 10 amp brushless motors?
witch one of mosfet or power transistor is suitable for this application?

[danadak]

If you contact sales rep/fae at vendor of choice they can guide
you based on your requirements. Plus they will have market knowledge.
"For example we MAKE 25,000,000 of these a year, they are a high
runner, and costs are reflected by that whereas your other choice
does not get much volume (read won't be around much longer)"................

If you go to vendor site they have tools that filter out for the package,
current, V you want to make life easy.


Regards, Dana.