TOP261EN oscillating voltage with load
Problems with power supply 57.6 VDC 4A x
1. I have the output from this source another card with 3x LM2576 and when I connected to the plate voltage swings and is not stabilized.
2. When you unplug the card and connect again the voltage stabilizes.
3. When I remove the pin zumper X and put a 6.98K resistor to the source voltage rises until reaching a 93VDC and burning around the feedback loop circuit. Only works with zumper.
4. By adding the diode to reduce the tension on the TL431, the reference voltage of the resistors does not dry the normal calculation, this effect could help me?
5. I put a set of resistors simulating a load of 250R at the exit of the source voltage is oscillating. This happens only at startup.
6. Until the rectifier is on a separate plate and 1.5 mm cable is connected to the capacitor, that cause some of these problems?
When I add any initial charge, the voltage fluctuates, when I no load can connect any load that works.
Any help is welcome for I am with my deadline to deliver the prototype estorado and is the first source with the TOP261 I have problems.
Thanks
Comments
The problem persists. When a low voltage reference of the TL431 and put the load, the problem does not happen, only when I lift up the voltage of 50V. I really need help to solve the problem. Just at the time of start. When I add the load then the source behaves normally.
Thank you.
You will need to do phase/gain analysis of your supply. If you do not have analyzer then you could rent one. If you are not familiar with how to do this you will need to lear how or hire contractor
friends,
After much effort and many sleepless night! Apparently the problem was solved. The problem that I do not know which of the shares decided, how important it is working. The following shares made below:
1. Added snubber between drain / source TOPSwitch.
2. Added Snubber diode in the secondary.
3. Added Soft-finish (previously added more not solved the problem).
4. Increased the R8 to 6.8 K.
5. Recoloquei checked and the heat sink TOPSwirch.
Do not understand a question, when I add the Zener in series because of the TL431, the calculation of the resistive divider not hit, I thought the resistors by trial and error. What happens then?
I appreciate the support in solving this problem.
C12 is too small(1nF) should be something closer to 0.1uF.
You may need a lead network across R11 -- something like 10nf and 22K in series which would be placed across R11.