Hi,
I am using a DCP020515D to convert 5V to 15V. I would like to minimize the output voltage ripple to under 15 mV if possible. Can TI recommend any output capacitor (possibly 10uF with low ESR from my calculations) that would do the job assuming that the input voltage is perfectly flat. Thanks
Amish
Amish:
I attached a PI filter using ceramic capacitors and ferrite beads( 1-5uH) for this request.The average ripple reduction is 10 -15db.
Tom
3326.10411772_3.pdf7411.10411772_2.pdfHi Tom,
Thanks for the solution.
1) Is there a maximum ESR that the caps should have.
2) Does the size of the decoupling caps used at the loads matter?
I attached part of the design that uses the output.
Thanks
Amish3617.10411772_1.pdf
Thanks for the response .
1. The ESR on ceramic capacitors at this switching frequency is typically 3-6mΩ.
2.The ideal decoupling capacitors are ceramic types with X5R and X7R tolerance rating with 1.0uf to 4.7uF .Do not use Z5U or lower tolerance ceramic capacitors due their poor temperature ratings.
Ok sounds good. I will try it out. Thanks,
Hello together,
the post is already some months old but I have a question concerning the DCP02 series ripple filtering, too. I already wrote Tom an Email, but maybe it's better if I post it in the forum too:
There is one specific question which wasn't answered in different posts: What's about the Y-Capacitor between input GND and output GND? Other DCDC Manufactures propose this capacitor with high voltage durability and low capacity (2.2nF - 100nF).In our tests it was shown, that this capacitor has much more positive effects than all PI-filtering at the input or output side of the DC/DC-Converter.Does TI also recommend this GND/GND coupling? What's about the galvanic isolation? Are there any side effects that come with this coupling?
Thank you very much for your help!RegardsChristoph
The isolation coupling capacitor between Vin(-) and Vout(-) can be used for reducing EMI and reflected ripple. However, the voltage rating should be equal or greater than the converter 1 second isolation test or 2000V. The design of the DCx converters is fro ground fault isolation applications.