TNY 284 - 4W design - Regulation distorted by Loading.

Posted by: kiranlaleu on 12/28/2016

Hi,

I have tried to build a smps with 5V, 0.8 A output to operate at universal voltage. From the design file generated by PI Expert 9.1.The device will power up and and function to give 5 V at the output at "ZERO" loading (No load condition).

But the moment I connect a Electronic Load the voltage will start to sink from 4.6V(Voltage when loaded - at near 0.1A) to around 3.9V(at full load of 0.8A). But still the circuit was able to handle the full loadcurrent for quite sometime and also I was able to still make it work at 0.9A above the design limit without IC shutting down.

What could be the possible reason of the voltage dip when loaded.

Thanks,

Kiran

Files

PI integrations-TNY284.png (87.01 KB)

TinySwitch-4_PIDesign.uds (421 KB)

Comments

Can I kindly request anyone to please look at this problem and suggest me what to do.

Hi Kiran,

Thank you very much for choosing Power Integrations.

I can see that you are using a zener as regulator. Actual zener diode voltages will depend on the current flowing through it and every zener diode has different V-I characteristics. Try to use a 5.1V zener. This will allow the output voltage to still remain within regulation even at full load.

Hi, I was trying to replace the 3.9V zener with the 5.1V zener as you have told. Now presently a new problem has arised where the circuit output will vary from 4.7 to 5 V and then suddenly glitches to above to 6V to 7V and continues to do so.

Can you tell me what might be the reason behind this. I have checked for loose and open connection. But could not find anything

Do you know what might be causing it ?

Can you tell me what might be the reason behind this. I have checked for loose and open connection. But could not find anything

Do you know what might be causing it ?

I changed the zener back to 3.9V but even now the voltage output is showing glitch...How to solve this please..?

Update :-

After one of your guys asked me to change the zener by 5.1V I did that and from then on the supply is showing a glitch in the output...to add to that...circuit after few testing is showing output voltage of 12V.

In addtion I changed the zener back to 3.9V. Even now this glitch is not going away...

Is this happening at no load or full load? If no load, try putting a 500 ohm, 1/4W preload resistor across the output.

Could you also please send me a screen capture of your drain to soure voltage at no load and full load with the time/div of the oscilloscope set at 20us/div?