This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LP2951-Q1: Output capacitor ESR values at what frequency

Part Number: LP2951-Q1

Tool/software:

Datasheet only show the output capacitor ESR value, but the relevant ESR value at what frequency is not specified. I want to know the specifical frequency. Does it relevant to 500kHz? See below

  • Hello Aman.

    The range for ESR of the output capacitor is 30 mΩ - 5Ω across all frequencies. The output capacitor must have a resonant frequency greater than 500 kHz. The output capacitor will suffice so as long as:

    • Its minimum impedance (at resonance) occurs at a frequency > 5090 kHz
    • This minimum impedance (ESR) is 30mΩ
    • The maximum ESR is 5Ω
    • The capacitance value is met with tolerance and derating included

    Hope that helps

  • Hello Ishaan.

    I used a ceramic capacitor the ESR and resonant frequency see below. and a ceramic capacitor ESR at low frequency(400Hz) hit the upper limit. I look up a lot of ceramic capacitor specification, it seems that higher ESR value at low frequency is the common characteristics of ceramic capacitors.

    Can this ceramic capacitor use as the output capacitor 

  • Hi Aman,

    This capacitor cannot be used as is. The minimum ESR at resonance is less than 30 mΩ. This can be addressed by adding a resistor in series with the capacitor such that the minimum ESR requirement is met. The maximum ESR is evaluated at resonance as well so that will not be an issue here