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TPS7A49: TPS7A4901 as replacement of Semtech TS31223

PVERA
Prodigy 90 points
Part Number: TPS7A49

Please find the attached design based on Semtech TS31223 regulator (figure A). I would like to replace TS31223 with TI TPS7A4901 as indicated in figure B. I would like to know if I have correctly used TPS7A4901. My new designing is overheating, so would to know if I made a mistake in the new design.

  • 0
    TI__Guru 55940 points
    Hi Pvera,

    Since you mention that your LDO is overheating, could you provide Vin (PDC) and Iout?

    Also, since TS31023 has a different pinout from TPS7A49, when you relaid out the board, please confirm that you provided ample copper particularly around the thermal pad to sink the heat dissipated by the LDO.

    Very Respectfully,
    Ryan
  • 0 in reply to Ryan Eslinger
    Prodigy 90 points
    Thanks Ryan. I am looking at adding ample copper. In the mean time do I need the Zener Diode as in figure A for the design in figure B connecting to PDC.
  • 0 in reply to PVERA
    Prodigy 90 points
    The Vin(PDC) is 25VDC
  • 0 in reply to PVERA
    TI__Guru 55940 points
    Hi Pvera,

    Due to the large voltage drop (Vin - Vout = 25 - 3.3 = 21.7 V), it is not surprising that your application is generating a lot of heat. The amount of heat will be dependent on Iout and the amount of copper you are able to put around the LDO to sink the heat (the more copper you can put around the LDO the better). If you would like to reduce the heat in the LDO, you could also consider reducing the headroom (Vin - Vout). You can do this by placing a DCDC (most efficient method), another LDO (highest system level PSRR), or even a power resistor in series before Vin of your current LDO. The first method (DCDC) will reduce the amount of power dissipated in your system, while the other two will simply spread the heat more efficiently across your board.

    Very Respectfully,
    Ryan