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PTH08T220WA Ripple Question_Re

GO Dennis
Prodigy 20 points

Hi....

i am using  PTH08T220WA and Vin = 12V / Vout = 0.9

If the output vout to 0.9V, Ripple of 61.77mV occurs.(Measured waveform reference.)

What causes this problem to occur? What causes this problem to occur?

Thank you.

Schematic)

<Measured waveform>

  • 0
    TI__Mastermind 38230 points

    Dennis:

     PTH08T220WAx  requires a  minimum output capacitance of 220uf polarized . Your  70kHZ measured frequency is not related to the PTH08T220WAx switching ripple frequency of 300kHZ or 3.3usec period..

    The best  ripple  measure method   is use a close coupled scope probe  across a 10-22uF ceramic capacitor . The scope bandwidth should be 20MHZ  to eliminate "E"  stray field scope probe .

    My e-mail contact  is tguerin@ti.com for any addtional questions.

    Tom