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TPS25982: Power OR functionality

james calvert
Prodigy 65 points
Part Number: TPS25982
Other Parts Discussed in Thread: LM7480, TPS25940,

Dear Team

I would like to use two TPS259824 devices in power-OR situation from two batteries (as I like the features of this device: very low on-resistance, low on and off Iq etc etc)

Propose to have two identical paths, both paths comprising front-end LM74700 ideal diode controller (for reverse battery protection) followed by TPS259824. 

Outputs of TPS259824 are proposed to be connected directly together. Note, one battery will be absent at some times (during hot-swap of batteries)

Would use enable inputs on TPS259824 to turn each path on and off as required (would do this in overlap fashion to ensure power continuity on output, so system would at times be in power-OR situation.

To satisfy spec of max output voltage range of TPS259824, I would propose to add low voltage drop schottky in parallel with body diode in TPS259824 (to ensure Vout is never more than Vin +0.3V when device is switched off)

I'm aware of LM7480 device, but as not available yet in production quantity, so does not seem to be an option for me at the moment.

TPS25940 was also considered for this project, but possibly prefer above solution, as potentially offers a lower on-resistance solution.

Please can you advise if above proposal using dual paths of LM74700 & TPS259824 with connected together output is acceptable please?

Thank you for your consideration in this. James

  • 0
    TI__Guru 57737 points

    Hi James,

    Can you let me know your system specifications below,

    Vin(max)=

    Max Load Current in each path = 

    Max Cout =

    Minimum Rdson required/ Maximum allowable drop across FET = 

    The more information you can share with us about the application and needs, the better we can suggest you right parts from our portfolio.

  • 0 in reply to Praveen GD
    Prodigy 65 points

    Hi Praveen

    Thank you for your prompt response.

    Vin Max = 16V (The input on each channel is nominal 12V battery, but these may have elevated battery voltage due to just coming off charge)

    Max I in each path is 4.5A, but nominal I will be around 1A each path

    Max Cout is still to be determined on final design testing, but likely to be no more than 1000uF

    At 1A current flow in each path, would ideally like voltage drop (from battery to combined output) to be 0.05V max (the design is energy sensitive).

    Would also like quiescent current per channel to be ideally no more than 3mA when channel is on and ideally no more than 1mA when channel is off (again, due to being an energy sensitive design)

    Each channel will need the requirement to be turned on/off independently. Power-OR function also required to allow hot-swapping of single battery, and also allow for switching energy draw from each battery as desired with uninterrupted output.

    Inputs must allow for protection of circuit against accidental connection of reversed battery voltage.

    Thank you in  advance for your consideration in this.

  • 0 in reply to james calvert
    TI__Guru 57737 points

    Hi James,

    Thanks for your detailed response. I agree with you that LM74700 + TPS25982 would be the best solution for your required specifications.

    Do let me know if you have any further questions.