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How do I explain TPS92511 efficiency up to 95%

Kuo Duke
Expert 2040 points
Other Parts Discussed in Thread: LM3405

Hi All,

Why Common anode CC buck led driver efficiency can up to 95%??
With floating buck topology have relation?

The efficiency compare to LM3405(buck topology) is better 10%

  • 0
    TI__Mastermind 25500 points

    Well there are multiple reasons. First off you have to compare the efficiency for the same input voltage, output voltage, and output current since duty cycle is a big factor in buck regulator efficiency. Having said that the LM3405 generally will have lower efficiency given a maximum switching frequency of 500kHz (the datasheet graphs were taken at 300kHz). The LM3405 switches at 1.6MHz. It is commonly known that a higher switching frequency (much higher in this case) will reduce the efficiency due to the extra gate drive current required and the additional AC losses in the switch and diode. 10% lower efficiency at over 5x the switching frequency is actually pretty decent.

    The main point in the end is the LM3405 was not designed for highest efficiency in mind but rather solution size. Due to the high switching frequency the overall circuit will end up much smaller since the cap and inductor values will be about 5x lower.