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LM5050-1: How to use multiple FETs in parallel

Sadanori Kato
Guru 36510 points
Part Number: LM5050-1
Other Parts Discussed in Thread: TPS2412

Hi,

For the following LM5050-1 schematic, can the multiple FETs be used in parallel to share the load current(~20A)?
If no, could you please provide me the recommended parts number which can be used in the following case?

Best regards,
Kato

  • 0
    TI__Guru 57737 points

    Hi Saadnori,

    Yes LM5050 can be used to parallel 2 FETs for a total of 20A load current. It would be a good idea to put resistor on each mosfet gate signals to prevent gate from ringing during fast turn-off events.

    If the load current is even higher and you require more FET's I would suggest you to consider using LM74700 as it has higher gate current to drive bigger MOSFETs for high current applications.

  • 0 in reply to Praveen GD
    Guru 36510 points

    Hi Praveen-san,

    Thank you for the information.

    There is mentioned in TPS2412 data sheet as follows if using the multiple FETs in parallel.
    So, does the LM5050-1 work normally even if the Rds(on) of each FET(Q1 and Q2) varies?
    Moreover, the power supply voltage VIN may be 2V, so the LM74700 cannot be used.

    Best regards,
    Kato

  • 0 in reply to Sadanori Kato
    TI__Guru 57737 points

    Hi Saadnori,

    LM5050-1 also has linear gate regulation control similar to that of TPS2412. The regulation threshold of LM5050-1 is VSD(REG) = 22 mV.

    When the FETs are in Saturation region there will not be natural current sharing between them like in triode/ohmic region.

    So, the statement you highlighted holds good for LM5050-1 as well. As worst case analysis you can consider that one FET takes the entire current as long as the voltage across the FET crosses VSD(REG).

  • 0 in reply to Praveen GD
    Guru 36510 points

    Hi Praveen-san,

    Thank you for your prompt reply.

    I understand.

    Best regards,
    Kato