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UCD9090: A question on voltage margining scheme

Ella KIM
Expert 4212 points
Part Number: UCD9090

Hello,

I'm looking at SLVA845A as my customer wants to vary the output voltage (nominal 48V, it varies in a range of 36 ~60V). It looks it can be implemented by controlling VOH, VOL, FPWM.

I also look at SLAAE22 and it just applies DC voltage on FB pin, not PWM+filter. Per my understanding both applying DC voltage on FB node and applying PWM thru RC filter results in the same result - output voltage scale. I wonder what the advantage of using PWM and filter. Why not UCD9090 just apply DC voltage to FB node?

Please help advise. Thanks.

  • +1
    TI__Guru 65610 points

    Hi

    UCD9090 does not have a DAC output to adjust the FB via DC directly so we use the PWM + filter to generate a DC voltage to impact the FB node.

    Both are the same from the principle as you understand. 

    The good thing is that PWM + Filter can provide more resolution but DAC requires less external components.

    Regards

    yihe