Lm2595 Saturation voltage

Discussion in 'General Electronics Chat' started by mendiola_loyola, Feb 19, 2011.

  1. mendiola_loyola

    Thread Starter New Member

    Sep 18, 2010
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    Dear All:

    Is Saturation voltage part of the regulator Dropout voltage?

    The datasheet states that the Vsat is 1 Volt with a Load of 1A.

    Could you help me please?

    Regards
    Alfredo Mendiola Loyola
    Lima, Perú
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    1,728
    Well, "dropout" is usually used in terms of linear regulators, where the LM2595 is a "buck"-type switching regulator.

    If your required output voltage is within a couple of volts of your input voltage, you should be looking at a different type of regulator.
     
  3. mendiola_loyola

    Thread Starter New Member

    Sep 18, 2010
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    What does "Saturation voltage" mean on a Buck regulator?

    Regards
    Alfredo Mendiola Loyola
    Lima, Perú
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    That's with no output inductor, no output diode, and the feedback shorted to ground - basically, the regulator is putting out all the current it can, and there is still a voltage decrease from the input to the output. In this context, it is similar to the "dropout voltage" of a linear regulator.

    However, when you add the inductor, diode, and connect the feedback normally, you'll see a further decrease in the output voltage due to the parasitics involved. So, the saturation voltage is related to the minimum voltage input required to maintain an output voltage, it's not the same.
     
  5. mendiola_loyola

    Thread Starter New Member

    Sep 18, 2010
    16
    0
    Thank you Sergeant Wookie.

    Regards
    Alfredo Mendiola Loyola
    Lima, Perú
     
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