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Original question:

LM5177: Power inductor selection

LM5177: LM5177

hakan özkahraman
Prodigy 30 points
Part Number: LM5177

Hello Sir,

In the LM5177 datasheet, at first page, it says, switching frequency is fixed for all three modes. And also max frequency is 600kHz. But in the 8.3.6 Section, the switching frequency can be changed to 2.2MHz, and also it says, "the switching frequency can be dynamically changed during operation by changing the current flowing through the resistor"  . And Fig.8-9 and 8-10 shows the ways to change the switching frequency. In fact, I prefer to change the switching frequency to get maximum performance. I want to ask you , is it possible? Our application specifications are below;

Vin : 10-55V

Vout : 24V

I out max : 7A

regards

  • +1
    TI__Mastermind 29710 points

    Hi Hakan,

    Thanks for using the e2e forum.
    The LM5177 has a frequency operation range of 100kHz - 600kHz. Section 8.3.6 describes how the fsw is set through external components.
    The example of fsw > 2MHz is for illustrating how the resistance is calculated. If the resistance would be set to 2.2MHz through external components, you would operate the device out of specs and damage or malfunctioning of the device would be expected.

    Operation in fixed frequency means the device does not change its fsw on its own. If the frequency setting resistor would be changed during operation, the fsw of the device would follow the settings.

    Best regards,
    Niklas