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LM66100: Dual Power Rail Oring

Jebin Satheesh Kumar
Intellectual 280 points
Part Number: LM66100
Other Parts Discussed in Thread: TPS2116, TPS2121, BQ24295, BQ21040

Hi Ti Team,

     I have used LM66100 for Dual Power Rail Oring Purpose. I would like to understand this circuit will work in all scenarios.

Battery Charging Condition : Battery 0V and increasing voltage from  0V - 4.3V(based on Charge current) 

Battery Discharging Condition : from 4.3V 2.8V then 0V.

Jebin 

   

  • 0
    TI__Genius 10652 points

    Jebin, 

    Yes, the circuit will work in this configuration for what you are trying to achieve. Please also take a look at TPS2116  or TPS2121 which has the same functionality in 1 IC, along with other features. 

    Best

    Dimitri

  • 0 in reply to dimitri james
    Intellectual 280 points

    Hi Dimitri,

       What is the minimum voltage difference required between the rails, for the change over? 

    Can  TPS2116  or TPS2121  are can be used as a Dynamic power path management controller in the Place of BQ24295(for Battery charging planning to use BQ21040)?

    The reason being replace BQ24295 with TPS2116 and BQ21040 is when the battery drained and goes to 0-Volt and kept the battery without charging for couple of days.  In this condition BQ24295 output not maintaing 3.7V as mentioned in the datasheet. To reach a 3.7V its takes some time 5-10Min! during this time our HOST controller(Host min voltage 3.4V) will restart continuously and some of the memory blocks are getting corrupted.

    Let me know can this combination will solve my problem.

     

    Jebin

     

  • +1 in reply to Jebin Satheesh Kumar
    TI__Genius 10652 points

    Jebin,

    In the configuration with LM66100, the battery once the battery voltage drops several 10s of mV below the 3.3V rail you have, it is possible to use a resistor divider here as well to adjust the voltage, but i don't commonly see it. 

    The advantage of a powermux is that you can configure with a resistor divider at what voltage you want to switch from the battery to the PRI_3.3V source. E.g. you can configure it to switch at 1.5V, 2.2V. Additionally , you can add hysteresis, selectable current limit and OV and both channels are using back-to-back NFETs which are extremely effective at blocking reverse current compared with LM66100 which have single FET toplogy. Furthermore, the Powermux can take power from either the 3.3V or 3.7V supply whichever is online. This would mean that the IC will be ON and monitoring both supplies at all times. 

    Disadvantage is that there is no integrated boost function with the solution you have proposed with Powermux. 

    Best

    Dimitri