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Help me with designing MOSFET- bridge for Toshiba TB6575FNG

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v_c

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Re: Driver MOSFET's

looks like you can configure the IC with the OS pin (pin #3) on page 3, to take either all n-type or p-type for high-side and n-type for the lowside. Even though they say n-channel and p-channel on the first page, the application circuit has bipolars -- very confusing. I think maybe it is just a Japanese symbol issue .
 

artem

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Driver MOSFET's

as far as chip supplied current is enough you can use bjt or darlington or... The question is there motor which eat up to 20mA * beta of tranzistor?
 

v_c

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Re: Driver MOSFET's

Artem,
don't you think the usage of "n-channel" and "p-channel" is misleading on page 1 of the datasheet? When the word "channel" is mentioned, I would immediately think about a FET (field-effect transistor) of some kind.

If n-channel MOSFET were to be used I would expect the integrated circuit to have a charge pump inside to drive the n-channel MOSFETs on the high-side.

Best regards,
v_c
 

artem

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Driver MOSFET's

It is conventional to use mosfets , but igbt's as well . So if chip outputs, timing and load current are suitable for particular driver we can put whatever we can fit into requirements. For MOSFET there is Vgs does matter for bjt - Ib , so lets give a current via resistor and bjt will be happy to switch as long as motor current is less than mentioned above ?

I could not find a mistake from example aplication - except base resistor values where not mentioned - for bjt these are critical.

Am i wrong ?

Added after 3 minutes:

i dont assume that whatever is put into documenst is rule of must of course if one condition is met - design adaptation shold follow physical and logical sense. May be i dont have such .)
 

v_c

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Re: Driver MOSFET's

Yes, base resistors are very important for a BJT drive.
This IC would not be my first choice for a drive. I would suggest looking at the Infineon web site. I know that they have H-bridge and H-bridge drive for single phase stuff -- I have not used their three-phase stuff but I am sure it is there.

https://www.infineon.com
 

artem

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Driver MOSFET's

to be honest i never used them )).
 

Beffo

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Re: Driver MOSFET's

Thanks!
Probably the bjt in schematic is just a symbol issue.

And of course I could use the OS pin, just didn't se it. :)

I've had a hard time finding three-phase bridge drivers, but the infineon seems interesting...

v_c:
"This IC would not be my first choice for a drive"
why not?

My reason to use this ic is that it has an analog input, it can handle sensorless BLDC's, and I will use it in a hot or cold environment, like a truck.

I think it looks quiet simple, but it probably needs a lot of trial and error to determining the correct values for components and startup-cykle etc.

What do you think?
Regards
Beffo
 

jymoo30

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Re: Driver MOSFET's

i suggest u to change the MOSFET to IGBT since the MOSFET is unstable and it will always accidentally to be conducting in unwanted condition and this will result in short circuit in H bridge.
 

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