There are a couple of things that might be happening. Does the output voltage increase as you increase the input voltage? If so, the output windings might be reverse phased. In a conventional flyback design, the start of the primary should be connected to the TNY drain. In each secondary, for a positive (+) output voltage the secondary start should be connected to the anode of the output diode. When the primary switch is "on", there should be a negative voltage at each output rectifier anode. If the outputs are mis-phased, the output voltage will track the input voltage instead of remaining relatively constant.

Also, unfortunately, this sort of output arrangement is the worst case for  cross regulation, with only the 5V output in the control loop and the other 15V outputs floating free with no common ground.  The preload resistor value on each of the 15V outputs is too high (150k) to exert any significant control over the output voltage. 

The first thing to do is to make sure that the 5V output is adequately controlled by the AS431.If this is OK, you can then proceed to work with the value of the preload resistor on each of the 15V outputs for better control over the output voltage. I strongly suspect that the optimum value will be much smaller than the 150k currently used.

Also, keep in mind that in a system like this with only one controlled main output and four outputs with separate grounds, the cross-regulation will likely be a problem, with the voltage on the 15V outputs varying as a function of 5V load. This can be helped to a certain extent by extra preload on each output, but the regulation will never be perfect.

On another note, the resistors needed for undervoltage should total to around 4.56 M instead of the value currently used. This should increase your startup voltage to ~85 VAC

Hi Wrench

Thanks now my SMPS turn on at 80Vac. But when i reduced the voltage below 80Vac input it is not turning off. it is turning off at 22Vac .

can you please let me know what is the problem.

Regards

Hemanth

I think what you might be encountering is the extended on-time feature of the Tiny-4. This feature allows extended  low voltage operation for a given size of input bulk capacitor. You might want to try reducing the size of your input bulk capacitors to compensate. For reference, what is the total output power of your power supply as designed?

i have designed output power is 5.65W

According to the schematic you presented at the beginning of this thread, you are using a total bulk capacitance of 44uF for a supply with an output power of 5.65W. This is very much in excess of what is necessary at this power level. The general rule of thumb is 2-3 uF/Watt for a universal input supply. This extra capacitance, combined with the extended  on-time feature of the TNY-4 may be the reason why your supply is turning off  at such a low input voltage. Can you try reducing the total capacitance to 10-15 uF and see if that changes the shutdown voltage? 

we got another problem that our system work fine for 30 sec as soon we switch off supply and turns on back the TNY 287K is damaging. what is reasons for damaging we have connected the input capacitor 44uf will that leading the problem. i am not getting the reasons for damage please help me?

You might have to sacrifice a device or two to figure things out, but it would be useful to monitor both the drain voltage and drain current  during the event that is causing the damage to verify whether the problem is caused by excessive voltage or excessive current.. Please also check the components in the drain snubber to make sure nothing is open circuit.