Hi Excellent Ti Guys,
I build a circuits boot the +5V input from USB (after hot-swap) to +/-15V output with TPS61041.
But I it's output ripple (voltage ripple) is very high, peak to peak valued over 1V.
Ciucuits like picture up shows, and output are filter by circuits like below shows:
L1: 10uH; R1: 140k; R2: 12.1K; CFF:47pF;
I try to modified L1 and Cff as datasheet described but nothing improve.
Some formula have offered in it's datasheet, but they all have no units, I also use the tools link below for parameter calculation.
but it's result conflict with the datasheet shows. So, I am confused about how to reduce the output ripple to the value I want. (Example: 10~15mv).
Could you offer me some suggestion?
The TPS61040 is a hysteretic converter and so needs a minimal amount of ripple for operation. I have never seen it operate with less than ~50mVpp of ripple. To reduce the ripple, you will need the smallest inductor value to give you the maximum 1MHz switching frequency and a large ceramic (or other very low ESR) output capacitor. You should be able to reduce the ripple with a post output filter, similar to what you have shown above but the filter will need to have a roll off point at least 1 decade below the switching frequency.
If this doesn't work, then try moving to a TPS61080 or TPS61170. Figure 25 of the TPS61080 datasheet is your application.
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with respect to these materials. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.