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TPS2493: Reduction of Q current.

Aidan Walton
Expert 1095 points
Part Number: TPS2493
Other Parts Discussed in Thread: LM5060

Hi,

I'm designing an battery powered system using the TPS2493 as an ORing power controller for battery or mains power sources. I note the datasheet for the TPS2493 indicates that Q current in the 'disabled' state is around 120 - 250uA. This is not entirely insignificant.

Do you have any recommendations/feasibility of using a FET on its ground pin and other associated GND connections that could be floated when the battery is not required. I am trying to simulate with TINA, but I'm not convinced of the model behaviour in this configuration. 

I'm considering using a FET with around 100mohm RDS and approx 3A capable, that will pull down all the ICs ground referenced connections when required. Has this approach to reducing Q current been tried before with the TPS2493?

Thanks

Aidan

  • 0
    TI__Guru** 106251 points

    Hi Aidan,

    We have not tried ground disconnect approach with TPS2493.
    Can you share more information to suggest suitable options.
    1. what is the mains power source and battery (min, max) voltages
    2. max load current
    3. which protection features are important: overload, reverse current, reverse battery protection ?

    Best Regards,
    Rakesh

  • 0 in reply to Rakesh
    TI__Guru** 106251 points
    Hi Aidan,

    Please provide details on the requirement

    Best Regards,
    Rakesh
  • 0 in reply to Rakesh
    Expert 1095 points

    Hi Rekesh,

    Hmm, I shall give you the data, but I don't understand why this is so important in this case. Max voltages are 62V, load current 17A, all features needed, but I'm using LM5050 as reverse protection. 

    What I am trying to avoid is having the TPS2493 sitting pulling 200uA constantly from a battery that is not active. My incoming battery connection, is directly connected to the TPS2493, with only fuse and TVS before its VCC pin. Therefore even when the system is not active there will be Q current through the TPS2493. 

    Now I realise that 200uA is very little, however, I am simply trying to ensure that Q draw from the battery as at absolute minimum.  If this turns out to be impossible, then I might just have to live with this.

    However, if I can float the entire IC with an FET then potentially I can overcome this trickle. I realise there are other implications such as probably having to use diodes on the pins interfacing low voltage control circuits, but to be honest I will probably do this anyway, just in case the IC fails.

    Still, I wonder if the TPS2493 will be happy having a small resistance in its ground path?

    Aidan

  • 0 in reply to Aidan Walton
    TI__Guru** 106251 points
    Hi Aidan,

    LM5060 is a good option to meet low IQ (in off mode) 15uA.

    Still, I wonder if the TPS2493 will be happy having a small resistance in its ground path?
    It should not be a problem. However, I suggest to validate under all fault conditions and proceed.

    Best Regards,
    Rakesh