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LM27403: LM27403 Vout Accurate question

Part Number: LM27403

Form my test by LM27403 EVM and my PCBA, find out different date code had different Accurate, How to solve this Issue?

Test condition: Vin = 12V, Vo = 5V, Io = 12A and target Vout +/- 1%.

Date code: 7CAK5NU / Full load = 5.008V / No load = 5.010V.

Date code: 8BA802U / Full load =5.004V / No load = 5.020V

B/R

James Su

  • Hi James,

        A +/-1% on 5V output is 50mV of tolerance. The measurements that you are showing are much lower than that. Any concerns with that?

    Regards,

    Gerold

  • HI Gerold,

    Sorry, I may not have expressed it clearly before. I mean that Load Regulation will have different measurement results on different date codes, and the difference is very big. Load Regulation = (No Load Vo – Full Load Vo)*2/ (No Load Vo + Full Load Vo)
    Therefore, the Vo value measured at the no-load and full-load values will be calculated. The Load-Regulation in the EVM manual is 0.2%, as shown below, and the EVM I adjust to Vo = 5V when the Load regulation is < 0.2%, but I am up. My pcb board,
    The Load-Regulation measured by different datecode is 0.04% and 0.32% respectively.
    Any recommend for layout or can help to check ?

    Regards,
    James

  • James,

    If you take the 8BA802U date Code IC and place on the 7CAK5NU date code IC board, and vice versa

    Does the load regulation stay with the IC or with the PCB. 

    If the load regulation stays with the board, a review of the layout may be helpful.   

    The voltage reference of the device is +/-1% over the temperature range so device to device there can be so variation.

    Regards,

    David