This thread has been locked.
If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
Part Number: TPS7A84A
I am currently looking at my options for filtering out some 900KHz supply ripple using an LDO. The application requires that the LDO be able to source >= 2.2A (>3A preferred for derating), and be able to output 5.0V (external resistors OK).
I found the TPS7A84A and TPS7A85A in your catalog and they seems OK, but using the parallel capacitor combination suggested in 184.108.40.206 it seems I only get ~20dB of power supply rejection at 900KHz on either part.
Can I use the capacitor values I choose and the boost circuit described in 220.127.116.11 of both datasheets (http://www.ti.com/lit/ds/symlink/tps7a84a.pdf & http://www.ti.com/lit/ds/symlink/tps7a85a.pdf) to steer the PSRR transfer function to have more rejection at 900KHz? Do you have and application notes / reference designs about how to do this? Or should I look for other high current LDOs with wider bandwidth?
I understand you would like to filter 900KHz noise and the PSRR listed at this frequency is only 20dB. The built-in PSRR boost circuit in TPS7A85A is creating a peak between 200kHz and 1MHz as shown. The limitation with this kind of boost is that the peaking frequency cannot be accurately set and the peak will vary between 200KHz and 1MHz.
We currently are developing the next-gen of TPS7A84/5A and based on some of the test data, the PSRR near 900KHz should be able to improve to around 40dB. Samples of TPS7A52/53/54 will be available by the end of the year. Will this be something you would be considering with?
Regards, Jason Song
Please click the "Resolved" link at the bottom of this post if I have answered your question.
We are glad that we were able to resolve this issue, and will now proceed to close this thread.
If you have further questions related to this thread, you may click "Ask a related question" below. The newly created question will be automatically linked to this question.
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. 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.