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LM5069 Pch FET drive

K. Sasaki14
Guru 10200 points
Other Parts Discussed in Thread: LM5069, LM5060

Our customer is considering the use of LM5069 as attached file.
They would like to drive Pch FET. They don't use current and power limit.

Is there any concern about attached file circuit? If you have any, please let me know.
I think this using method has no problem, however I think they should connect OUT pin to GND.

Best Regards,
Kohei Sasaki

  • 0
    TI__Genius 12570 points

    Hi Kohei,

     

    What are their application requirements?

     

    The LM5069 features a charge pump so that customers may use an NFET, which is typically cheaper than a PFET for the same Rds-on performance. The LM5069 also features active current limiting and power limiting.

     

    If they do not need these features, then there may be a better part suited for their requirements, such as the LM5060:

     

    Thanks!

    Alex

  • 0 in reply to Alex Triano
    Guru 10200 points

    Their requirement is FET ON/OFF and slew rate control.

    The reason for using Pch FET is because they don't have registered Nch FET which is meet their requirement size and on-resistance.
    The reason for using LM5069 is because LM5069 is registered component.

    Does this their using method have any problem? 

    Best Regards,
    Kohei Sasaki

  • 0 in reply to K. Sasaki14
    TI__Genius 12570 points

    Hi Kohei,

    As mentioned, PFETs are typically more expensive than NFETs for the same Rds-on requirements (and power capability/SOA).

    Therefore, this implementation greatly differs from our typical application circuits. We believe it should work for basic on/off control without current limiting, power limiting, or circuit breaker shutdown. However, we would recommend the customer test this topology on our EVM.

    As you mentioned, the OUT pin should not be floating.The GATE voltage is clamped using an internal zener from GATE to OUT. Thus in this topology, OUT would need to connect to GND.
     
    Thanks,
    Alex.