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LM5150-Q1: N-channel MOSFET selection

Part Number: LM5150-Q1

Hello Team,

My customer asked if the N-channel MOSFET of LM5150-Q1 can be changed from NVMFS5C466NLT1G to IPZ40N04S5L-7R4 or IPZ40N04S5L-7R4 due to limited PCB space. So please review and coment if the IPZ40N04S5L-7R4 and IPZ40N04S5L-7R4 MOSFET would be suitable for my customer's use case; VOUT=7.5V, IOUT=1A, fsw=500KHz, start-stop mode using LM5150-Q1.

Best regards,
DY

  • Hello Team,

    Let me correct a typo in the previous and modify the MOSFET part numbers as below.

    Best regards,
    DY

  • Hello Team,

    I have still not received any response on this.

    Best regards,
    DY

  • Hello DY KO,

    Thanks for your question. The important parameters to choose a mosfer properly are : VDS, IDS, dissipated power, parameters related to the efficiency of the converter (i.e. RDSon and gate charge) and temperature ranges. 

    For the NVMFS5C466NL:

    •  40 V Vds
    •  7.3mOhhm  RDSon
    •  Id 52A
    • power dissipation 37 W (room temperature)  

    The IPZ40N04S5L-7R4 might be a good replacement:

    • 40 Vds
    • 7.4mOhm RDSon
    • Id 40 A
    • 34 W of power dissipation (at 25 celsius degrees)
    • AEC Q101 compliant

    Please note that the MOSFETs also need to sustain the max peak inductor current of the design, so I would recommend to double check with the customer this parameter (since the original mosfet can sustain a higher current). I would also double check the VIN value that the customer is using. 

    The second transistor that you mentioned (SQ3418AEEV) might not be a good candidate because of the power dissipation capability (only 5W at room temperature which is lower than the mosfets above and it can also sustain an ID of only 8A). 

    To be sure, I would double check the complete design on WEBENCH as well (at the bottom of the page) https://www.ti.com/product/LM5150-Q1 

    Please let me know if I can help you furthermore. 

    Elisabetta 

  • Hi Elisabetta,

    Thanks for your response.

    I'll let you know if my customer has addional questions.

    Best regards,
    DY