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LM5026: How to reduce light load loss and no-load loss?

Part Number: LM5026

Dear Pros,

100W, DC-DC module use LM5026 ,24Vin,5Vout ,Topology: active clamp synchronous rectification 

 no-load current of more than 100 ma, Is there any way to reduce the no-load loss to improve efficiency ?tks.

  • Hello Cris,

    The major components that take in power at no load are:
    1. Xcap discharge resistor contributes significantly in high line conditions. One way is to reduce the x-cap value this will increase the discharging resistance and lower the power dissipated. Note: This will impact the EMI performance.
    2. If the leakage current of the input capacitors is high then that will contribute to standby performance @ high line.
    3. The snubber circuit dissipates the energy stored in the leakage inductance of the transformer to prevent a voltage spike at the start of the switching cycle. It is important to manage the dissipation of this energy for no-load conditions at no load the primary current will be Vin_peak/Rsense. substituting this in power equation= 1/2LIpk^2Fsw will give you the loss there.
    4. The RDson of the Mosfet can have a big impact on conduction loss.
    5. Transformer leakage inductance should be minimized.

    Are you using an SR driver on the output when it goes to low power mode?

    In general, you can check your design to reduce any static losses across Vin and Vout due to resistive dividers and bias currents for control circuits, minimizing these currents will help.

    I hope this helps.

    Regards,
    Sonal