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LM2621 output ripple?

Arnie
Prodigy 115 points
Other Parts Discussed in Thread: LM2621

Hi,

looking at the LM2621 data sheet figure 3 it would seem that the output ripple is VHyst. VHyst is indicated to be 30 mV (typ). Is this really the case or does the output ripple actually scale with the feedback voltage divider so that Vripple = VHyst*(Rf1+Rf2)/Rf2? If I have (Rf1+Rf2)/Rf2=5.5 for output voltage of about 7 volts, the ripple at Vout will be 5.5*30mV = 170mV (typ)?

  • 0
    TI__Expert 3870 points

    Hello Arnie,

    VHYST is defined as the hysteresis value of the internal comparator used for the gated-oscillator control scheme.  In other words, this paramater specifies the internal comparator hysteresis only and will scale with the FB divider ratio to reflect the total output voltage ripple.  Your statement is correct.

    Best Regards,

    -JPF