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LM5165: Purpose of Input ESR resistor?

Jonathan Jodoin36
Prodigy 20 points
Part Number: LM5165

Hello, 

The LM5165 EVM has a input ESR resistor of 4.7 ohms in series with a 1uF capacitor, and has another 1uF capacitor in parallel.  

I'm curious what the purpose of this input ESR is? and whether or not it can be removed or replaced with a 0 Ohm Jumper? 

I'm assuming it is to minimize inrush current and therefore can be removed with little impact on functionality.  I believe doing so will help with some emissions issues i've been having, as it will increase the effective capacitance at my switching frequency (300KHz). 

Thanks, 

  • 0
    TI__Mastermind 23845 points
    Hi,

    The purpose for R1 i believe is for dampening the input voltage if there is a long cable (inductance) from power supply to the input for the converter.
    You can try to put a 0 ohm resistor in there but make sure that the input does not exceed the abs max of the part

    Thanks
    -Arief
  • 0 in reply to Arief Hernadi
    Prodigy 20 points
    Hello,

    Thank you for your feedback. I have other components on the Input power and ground lines of this circuit that will to some pre-conditioning of the power (and a clamp to limit the input to the converter). I will remove the Resistor and see if it improves my results.

    Thanks,