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LM5060: four 48V batteries for selective output

rengui sun
Intellectual 680 points
Part Number: LM5060

principle:

The MCU controls the turn-on and turn-off of the MOS by controlling the EN pin of the LM5060. There is only one battery output at a time.

The picture is the basic principle.Because the paper is limited, only three batteries are drawn.

problem:

One battery output is turned on and the other battery output is turned off. The LM5060 that shuts down the battery will burn off.

The analysis may be that when the LM5060 turns off the MOS, the G pole of the MOS is about 0V, the GS voltage is -48V,

which exceeds the manual's ±20V, and the GS breaks down and burns the 10-pin GATE of the LM5060.

But the picture is a hole burned between the 1 and 2 pins. Please help analyze it?

Our solution is to connect a diode to the back of the MOS, but because the current is 40A, the diode consumes too much power,

and the solution is not very reasonable. Is there a better solution for 4 battery selection outputs?


  • 0
    TI__Guru** 105361 points

    Hi Sun,

    Can you share me schematic of one battery path for review.

    Best Regards,

    Rakesh

  • 0 in reply to Rakesh
    Intellectual 680 points

    Hi Rakesh,

    My previous analysis was wrong. The current analysis is when EN is turned off, because the out pin has no current limiting resistor,causing the LM5060 to burn out.

    When the current limiting resistor of out is 0, why is the hole burned between the Vin and Sense pins?

    The picture is one of the battery output principles, the other three roads are the same as this one.

    When debugging, because we did not read the manual carefully, we directly changed R28 to 0Ω.We only control the EN pin.

    After reading the manual, we will later modify R28 back to 20kΩ, R24 to 33kΩ, and the current limit value to 50A.

    Best Regards，

    Sun

  • 0 in reply to rengui sun
    TI__Guru** 105361 points

    Hi Sun,

    Thanks for the details.

    Higher value for R28 helps.

    Can you help with more information to propose right solution to you

    • What is the application use case ? Is it for Automotive market?
    • Is it ok if we OR the four 48V batteries ? In this case, the battery having highest voltage feeds the load? Is it acceptable

    Best Regards,

    Rakesh

  • 0 in reply to Rakesh
    Intellectual 680 points

    Hi Rakesh,

    1. This is our customer's customized product, not a product for the industrial control industry;

    2. We are still debugging and can receive it now.

    I still have two questions, please help reply:

    1. In the principle picture of the last reply, we input a series diode in BAT + to prevent the reverse connection from burning LM5060?

    We debugged yesterday and accidentally reversed BAT + and BAT-, LM5060 burned out.

    2. When the out pin is connected in series with a 20K resistor, the input is 0V and the output is 48V, will the LM5060 not be damaged?

    In practice, the voltage of the battery after discharge is 0V, and other batteries are still in normal output.

    We haven't found any problems in our tests these days, but we still want to check with you!

    Best Regards，

    Sun

  • 0 in reply to rengui sun
    TI__Guru** 105361 points

    Hi Sun,

    1A) Which pins are damaged.? I suggest one change in the schematic. Connect UVLO pin to VIN pin

    2A) I don't see any risk. However, I suggest to evaluate under all your possible use cases

    Best Regards,

    Rakesh

  • 0 in reply to Rakesh
    TI__Guru** 105361 points

    Hi Sun,

    Can you update on the damage pins. 

    Do you have any followup questions ?

    Best Regards,

    Rakesh

  • 0 in reply to Rakesh
    Intellectual 680 points

    Hi Rakesh,

    Sorry, I'm late to reply.

    1. The chip is only GATE pin can't output normally, which can't be seen by naked eye. We have solved the problem by adding diodes.

    2. I have no other problems.

    Best Regards，

    Sun