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LM25141: schematic check

Part Number: LM25141

Hi

Could you help check the LM25141 schematic as below and any need to adjust ,Thanks

LM25141.pdf

  • Hi Gareth,

    Please use the LM25141-Q1 quickstart calculator to check your design. Here are some comments on the schematic:

    1. 4.7uH seems a bit high for a 2MHz design (check recommended value in the quickstart file based on the 15mOhm shunt).
    2. Set LOL gate resistor to 0 Ohms (no need for slow turn off of the SYNC FET)
    3. Change high-side gate resistor to the HO pin (a slower turn-on is usually used to control the SW voltage overshoot). However, beware of increased losses.
    4. Check the MOSFETs have Rdson rated for Vgs = 5V.
    5. Connect VCCX to GND when not used.
    6. Use an input electrolytic for input filter damping.
    7. 10nF RES cap seems low - try 220nF for longer hiccup interval.
    8. Add spot for cap from COMP to GND (high-frequency compensator pole).

    Regards,

    Tim

  • Hi Timothy

    Thank you for comment

    When vccx floting IC has internal 5v driver?

  • Hi Gareth,

    We recommend typing VCCX to GNDif not used. Otherwise, if VCCX flots high and above the changeover threshold of 4.3V, it will turn off the VCC regulator taken from VIN, leading to controller shutdown.

    Regards,

    Tim