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  1. #1
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    P-channel Mosfet inverting control

    Hello! I need activate load when ttl 3v input low. Is attached shematic will work good?Click image for larger version. 

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  2. #2
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    Re: P-channel Mosfet inverting control

    Yeah it looks generally sound.

    There are IC's that can do this too (load switches) such as FPF2700.



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    Re: P-channel Mosfet inverting control

    Hi,

    It may work,

    But I'd rather use a single part called " high side power switch, active low".
    Besides the desired function in a single tiny device, it additionally includes overvoltage protection, overcurrent protection, over temperature protection. And usually cheaper.

    Just do a search at an electronic parts distributor. The provide interactive selection guides.

    Klaus
    Last edited by KlausST; 25th February 2020 at 07:26. Reason: Active high --> active low
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  4. #4
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    Re: P-channel Mosfet inverting control

    The 1k should be in the Drain of Q5 ... else it affects the gate drive volts of Q5 ...



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    Re: P-channel Mosfet inverting control

    Quote Originally Posted by KlausST View Post
    Hi,

    It may work,

    But I'd rather use a single part called " high side power switch, active low".
    Besides the desired function in a single tiny device, it additionally includes overvoltage protection, overcurrent protection, over temperature protection. And usually cheaper.

    Just do a search at an electronic parts distributor. The provide interactive selection guides.

    Klaus
    Thanks, I also find switch same us BTS443P, it need connect input to GND to activate load. Can i connect input directly to 3v ttl output to inverting operate or i need some convertor



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  6. #6
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    Re: P-channel Mosfet inverting control

    Hi,

    The chosen high side switch has the desired "inverting" function.
    But it has an internal pull up current source. The voltage may go up to the input voltage.
    A simple TTL signal may be problematic.

    But there are more high side switches with logic level input. Use a online selection tool.

    Klaus
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