voltage increases with high temperature .
sir,
we have kept the power supply for endurance at elevated temperature of 55c . it worked fine( 25v /2.5A) for 1 hour . but after a hour output voltage increased to 28v and it is stable at that point , current remains same (2.5A). we want to know why it is happening .if we bring the ckt to ambient , output voltage falls to 25v again .. this is repeating ..
Comments
sir,
i am attaching pi-expert design aswell as our design in 2 seperate rar files. pl look it into and help us in this regard ..
thanking you
regards
jRaj
jRaj -
I would start by trying to trace the problem to a particular area of the design. The two areas I would look first would be the OCP circuit and the TL431/opto feedback circuit.
For the OCP circuit, I would either lift R7 and R8 or remove U10 and then rerun your endurance tests.
If the problem continues with the OCP circuitry disabled, I would try replacing the 20k pot with a fixed resister of the correct value. Depending on the construction of the pot and how it reacts to changing temperature conditions, it's possible this resistance might slowly drift and changing your regulation setpoint.
If you're still having problems, I would experiment with heating up individual components on the board (optos, zeners, the TL431, etc) to see if there is some kind of thermal drift associated with one particular component.
Hopefully, this will help you find the problem. If you do, please let me know...I'm curious to hear back from you. If you're still not able to find the problem, please still let me know and we can work on this further.
-The Traveler
sir,
thank you for ur reply..
we will do what u said in another 2 days and come abck to you..
thanks
regards
Jraj
Jraj -
Will do. Please let me know.
-The Traveler
jayarajukm -
Could you please send me some further information about your design? A schematic would be helpful as well as any PI Expert or PIXLS design files that you have.
-The Traveler