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LM5021: Power management forum

Nelly Lin
Prodigy 20 points
Part Number: LM5021
Other Parts Discussed in Thread: UCC28C41, LM5022

does LM5021 can support 20W Vin 9~36V Isolator DC to DC power design ? and how to design small size transformer ?

B/R 

  • 0
    TI__Expert 8210 points

    Nelly

    No, LM5021 cannot support such a low input voltage.  The abs max UVLO turn on threshold on VIN pin is 23 V, so it cannot be guaranteed that LM5021 will startup with any input voltage lower than this.  Alternative devices that can meet your specifications are UCC28C41 and LM5022.

    To have a small transformer the switching frequency needs to be very high.  Both LM5022 and UCC28C41 are fixed frequency so they can be programmed with external resistor and/or capacitor to set a high frequency to enable small transformer size.  As for details on how to manufacture such a transformer we recommend that you reach out to your preferred magnetics vendor.

    Best Regards,

    Eric