Solution Finder Get Tech Support

Can i use TL431 for output of 100V

Posted by: thangaraju on

Please find the schematic designed using PI Expert for 100V output. My doubt is how can i use TL431 in feedback for 100V output, Because VkA of TL431 is max of 36V only.

Comments

Submitted by PI-Kenobi on 08/18/2014

What is the expected load regulation?

Submitted by thangaraju on 08/19/2014

Load Regulatio should be <=2%

For load regulation<= 2%, using a TL431 feedback is essesntial. Use the values recommended by PIExpert. The problem in using a TL431 based feedback is under load transients, when the VKA of the TL431 can be higher than the rated maximum. If load tolerance of 5% is acceptable, a zener feedback world be the best alternative.

Submitted by thangaraju on 02/03/2015

Suppose if i use TL431 for 220VDC regulation using Top250Y, during Feedback is regulated when ouput reach 220V. What will be happen before ouput reach 220V i.e before Ref pin receive 2.5V . Will be there higher voltage in Cathode of TL431?

Submitted by PI-Kenobi on 02/06/2015

Tha maximum rated voltage of the cathode of the TL431 is 36V (typically). At time(t=0), the load voltage is 0, thus the feedback voltage is zero, which also implies that the cathode voltage of the TL431 is 0. As the load voltage starts increasing, the cathode voltage of the TL431 starts changing to achieve the steady-state load regulation. In case of a 220V output, the most important consideration is biasing the optocoupler-TL431 feedback circuit such that even under conditions of no-feedback and full output voltage (possible when the feedback resistors are abruptly removed), the catchode voltage is less than the rated maximum.
So, to answer your question, yes, there can be a higher voltage at the cathode of the TL431.