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LM9061: Quiescent current and paralleling of MOSFET's

Supira Medical
Prodigy 130 points
Part Number: LM9061
Other Parts Discussed in Thread: LM5060-Q1, LM5060

Hi,

I have a couple of questions regarding the LM9061:

1. The quiescent current is too high for my application (5 mA when OFF).  Can I disconnect the power to the device after issuing an OFF command first and would this still provide bidirectional blocking with essentially zero Iq?

2. When using back-to-back MOSFET's, can one still parallel several FET's?  Are there any considerations for gate resistors, etc.?

Thanks for any assistance.

  • 0
    TI__Guru** 101911 points

    Hi,

    Thanks for reaching out!

    1A) The device needs to be powered to keep the MOSFETs in completely OFF state

    2A) Parallel FETs increases the effective gate capacitance and slows down the turn-off speed. The gate sink capability of LM9061 is very small. I would suggest to select a better option. 

    Can you share your requirements to suggest suitable solution. 

    • What is operating voltage and max load current?
    • Which protection features are needed ?
    • what is the target Iq-off ?

    Best Regards, Rakesh

  • 0
    Prodigy 130 points

    Hi Rakesh,

    Thanks for the quick response.  My application is for a reverse battery protection and disconnect switch for a 12 volt system and a max load of 100 A.  It will not be subject to PWM as it is primarily a static application.  The Iq needs to be as low as possible, ideally less than 50 uA since there will be extended periods of inactivity. The datasheet touts the ability of the LM9061 to drive several MOSFET's in parallel so I'd like to understand why you feel a better option is needed.

    TI's eFuse reference design (TIDUBK1B) has a bidirectional switch that meets my needs in that it allows for bidirectional current flow in the on state and bidirectional blocking in the off state.  I would like to find a way to use N-channel MOSFET's instead of the P-channel in a similar topology, if possible.

    Regards

  • 0 in reply to Supira Medical
    TI__Guru** 101911 points

    Hi,

    Thanks for sharing the requirements.

    For ON/OFF control in no fault mode, the controllers with even low gate sink/source capability would be fine. But in case of fault, large Vds gets developed across the MOSFET which will stress the FET with slow turn-off speed.

    LM5060-Q1 is better fit for your requirement. Please go through the datasheet and let us know if you have any questions.

    Best Regards, 

    Rakesh

  • 0 in reply to Rakesh
    Prodigy 130 points

    Hi Rakesh,

    Thanks for pointing out the fault conditions.  I have looked at the LM5060 in the past but it appears that this device will not allow inductive kickback current from returning to the battery, since the out pin is monitoring the voltage at the source.  Could you kindly confirm?

    Regards

  • 0 in reply to Supira Medical
    TI__Guru** 101911 points

    Hi,

    Correct. LM5060 won't serve here. You may need to go with discrete approach.

    Best Regards, Rakesh

  • +1
    Prodigy 130 points

    Hi Rakesh,

    Thanks for confirming.