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Power Tip 70: Use Weighted Feedback in Multiple-Output Supplies to Meet Regulation Specs
4/2/2014

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Figure 3: Degrading 3.3-volt regulation brings the 5 volt into spec. (See full-size image.)
Figure 3: Degrading 3.3-volt regulation brings the 5 volt into spec. (See full-size image.)

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Sanjib.A
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CEO
Re: Purpose of R1 and R5
Sanjib.A   4/17/2014 1:47:59 PM
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@Robert K: Thank you for answering my question and providing the reference to Power Tips 54 & 55. Practically, that inductor part would have some small amount of parasitic series resistance. Won't that help in damping the second stage resonance? I understand why the resistance might be required in the circuit for SPICE simulation.   

Robert K
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Re: Purpose of R1 and R5
Robert K   4/15/2014 1:28:23 PM
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The 0.5 resistors damp the filter's second stage resonance and make it easier to compensate the control loop at the expense of the output ripple.  See Power Tips 54 and 55.

Sanjib.A
User Rank
CEO
Purpose of R1 and R5
Sanjib.A   4/2/2014 11:37:10 PM
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What are those 0.5 ohm resistors R1 and R5 for? Are those necessary? Also I see that you have a 150 ohm resistor at the 3.3V output. Is that necessary to provide a minimum load? I find this tip very useful and would like to try experimenting. Thanks!

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