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: TPS61196
We got a question from our customer regarding abnormal phenomenon.
The phenomenon is that the anode voltage rise up to OVP point when the dimming duty is changed from 20% to 99.8% quickly. (then LED is light off because of OVP = 58.3V.)
The condition is ;
Vin=12V, 4 LED strings (Unused 2 strings are connected to ground.)
The phenomenon appears;
1.) when the dimming duty is changed from 20% to 99.8% quickly.
The phenomenon DOES NOT appear;
1.) when the dimming duty is changed slowly.(20% to 99.8%)
2.) when the LED strings are reduced to 3. (4strings to 3strings)
3.) when Vin is over 12.5V.
4.) when the dimming duty is fixed 99.8%.
At the beginning of question, we suspected not enough the performance of load transient. So, we asked them to change the compensation circuit at COMP pin or to add Cff.
However those were no effected.
I am at a standstill on this issue. What should I check any other point ?
(Would you mind if you check the schematics on private message? The schematic of their board is confidential information.)
Yes, you can send me the schematic through the Email. There are a few things that I want to check:
1. What's the LED forward voltage range for the whole current range?
2. Have you observed the Vin waveform when you quickly change the Duty from 20% to 99.8%, it may trigger UVLO?
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.
In reply to Sean Zhou:
Thank you for your support as always.
We had contacted each other about TPS61196 as well before. So, I will send some information by e-mail.
In reply to K.Hamamoto:
Sure, Let' talk about this off-line.
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.