Breaking News
Power Tips

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

NO RATINGS
View Comments: Threaded | Newest First | Oldest First
Sanjib.A
User Rank
CEO
Purpose of R1 and R5
Sanjib.A   4/2/2014 11:37:10 PM
NO RATINGS
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!

Robert K
User Rank
Blogger
Re: Purpose of R1 and R5
Robert K   4/15/2014 1:28:23 PM
NO RATINGS
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
Re: Purpose of R1 and R5
Sanjib.A   4/17/2014 1:47:59 PM
NO RATINGS
@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.   

Flash Poll
Radio
LATEST ARCHIVED BROADCAST
EE Times editor Junko Yoshida grills two executives --Rick Walker, senior product marketing manager for IoT and home automation for CSR, and Jim Reich, CTO and co-founder at Palatehome.
Like Us on Facebook

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
EE Times on Twitter
EE Times Twitter Feed
Top Comments of the Week