SMPS design of 5V and 2A using TNY268
Hi,
We have designed 5V, 2A supply using 3 phase input supply. Please find the attached schematic and reference document which we have used for designing.
We are giving single phase input as input and we are getting correct 5V ouptput. But we are facing one major issue that many times input protection resistors are burned. And when we removed those resistors our inveter trips. Input resistor rating is 10 Ohm and 1W.
Can you please let me know why these resistors are burning.
Thanks and regards,
Vishal
Comments
Hi,
I am facing this problem mainly when I connect external peripherals/connections like programmer or any connection which comes from my PC's.
Is this problem because of capacitor which isolates the primary and secondary side of transformer. So I think PC's Live/Neutral and SMPS input Live/Neutral are getting short because of this capacitor.
Please suggest...
Thanks and regards,
Vishal
Hi,
From the description that you have provided, this does not appear to be related to the power supply design but likely related to the interconnections that you are making with external devices.
I suggest you draw a schematic of the test setup with all the various devices connected and try to understand if you are inadvertently creating any loops as a result of your setup. Remember that the ground or "0"V from the power supply output in a PC is connected inside the PC power supply to input Earth so what you get from a PC as "0"V is actually connected to Earth.
Regards,
PI-Sarek
Good evening dear sir,
i have studied your article, now i need your help for my project. i.e., sir i wish to make 5V 2A power supply with single phase input by using TNY278PN. will you please suggest me proper circuit for that.
The 510V MOV is too low in voltage, your 10R resistors are not pulse rated for the start up current ...
Hi
The fact that the input resistor is damaged indicates that the input current is much higher than expected. what is the efficiency of the design as measured?
Input current can be high only if either there is something wrong with the deign (incorrectly would transformer), or incorrectly sized snubber clamp, or overload at output or incorrectly selected/damaged MOV.
Kindly verify.
Regards,
PI-Sarek