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LMZ22010 6pcs current share

PAN-M
Mastermind 8375 points
Other Parts Discussed in Thread: LMZ22010, LMZ22010EVAL

We are trying to configure the 60A power with six LMZ22010.

We have LMZ22010EVAL.

If the EVAL board is connected to four or more(Master/Slave) and connected to load, the output is the oscillation state.

Do you have not assumed that the EVAL board is connected a lot?

Or, this device impossible six current share ?

Regards,

PAN-M

  • 0
    TI__Genius 10115 points

    Hi,

    The eval board has been tested at 60 amperes.  You need to be very careful with the input supply as this can hit current limit very easily when drawing this much current.

     

    Also, make sure that only 1 board is configured as master. 

     

    Also check that the synchronization signal that is being used is clean.

    If the synchonization signal from the eval board is used, check that the clock signal is clean and that the peak voltage is higher than 1.8V.  This signal needs to have strong enough drive for the six boards, if it does not, you might need to decrease the resistance of resistor Rpull from 200 ohms to 100ohms so that it has enough drive.

     

    Let me know if this helps.

    Regards,

    Marc

     

  • 0 in reply to Marc Davis-Marsh
    Mastermind 8375 points

    Thank you Marc

    I checked the clock, and it worked.

    But, If the load of 30A, about 50mV voltage drops. (1.2V-4%)

    My request is within 3% at the 60A load.

    Is it possible if I make the new board?

    Regards,

    PAN-M

    1581.tek00015.tif

  • 0 in reply to PAN-M
    TI__Genius 10115 points

    Hi Pan,

    Glad to here that the change to the clock worked.

    In regards to the output voltage accuracy.  The evaluation boards are designed to regulate at the banana posts of the master board.  Make sure that you are measuring the output voltage right at these posts.  Also because the load current is quite high if you measure the output voltage at another point you will see additional IR drop.

     

    Regards,

    Marc

     

  • 0 in reply to Marc Davis-Marsh
    Mastermind 8375 points

    Hi Marc,

    I use banana posts. (source/load/mesure)

    When  the output load is 10A, 1.2V output becomes 1.08V.

    Regards,

    PAN-M

  • 0 in reply to Marc Davis-Marsh
    TI__Genius 10115 points

    Hi-Pan,

    Based upon your set-up it looks like you should be setting the bottom board (closest to the load) as the master.  You can then kelvin sense the output voltage at the banana connections of the bottom board.  Also, with this much current, i needed to create my own cables with much heavier gauge wire than the standard banana cable in order to keep the voltage drop between the boards and my load acceptable.

     

    Regards,

    Marc.

     

  • 0 in reply to Marc Davis-Marsh
    Mastermind 8375 points

    Thank you Marc

    I understood that it is the rough limit of the default evaluation board. I will try your suggestion, and will finish the evaluation on the EVM.

    Regards,

    PAN-M