Why two mosfets in circuit for "N-MOSFET driver"

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christoffert
Posts: 1
Joined: Mon Jul 17, 2017 1:31 am

Why two mosfets in circuit for "N-MOSFET driver"

Post by christoffert » Mon Jul 17, 2017 1:46 am

Hi, I have been trying to wrap my head around why two mosfets are necessary in the circuit for the Addressable N-Mosfet Driver and not just one? What are the differences between the two and what is the meaning behind connecting them in that way?

Circuit: https://cdn.shopify.com/s/files/1/0045/ ... 1977644917

Mosfet 1 - RJU003N03 Datasheet: https://media.digikey.com/pdf/data%20sh ... 003n03.pdf
Mosfet 2 - NTD5867NL Datasheet: https://www.onsemi.com/pub/Collateral/NTD5867NL-D.PDF

Thanks a lot.

Cheers
Christoffer

Officialuser
Posts: 2
Joined: Fri Nov 16, 2018 9:04 am

Re: Why two mosfets in circuit for "N-MOSFET driver"

Post by Officialuser » Fri Nov 16, 2018 9:14 am

I thought the first one had a smaller drive threshhold requirement, but it doesn't seem to. I am at a loss as well.

ilium007
Posts: 10
Joined: Sat Jun 16, 2012 8:32 am

Re: Why two mosfets in circuit for "N-MOSFET driver"

Post by ilium007 » Wed Apr 10, 2019 10:02 am

I came here to ask the same question ! I can't understand why the RJU003N03 is being used, the NTD5867NLT4G N MOSFET can easily be driven by logic level input.

Did anyone get an answer on why the smaller MOSFET is being used ?

Brissieboy
Posts: 149
Joined: Fri Sep 20, 2013 7:25 am

Re: Why two mosfets in circuit for "N-MOSFET driver"

Post by Brissieboy » Wed Apr 10, 2019 11:57 pm

Just a suggestion, but maybe because the WS2811 is a current driver device it cannot be guaranteed to reach appropriate logic levels to fully drive the NTD5867.
You could try an email to support@freetronics.com.au and see if they have design details.

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