WIY2263 (30W SMPS IC) HELP NEEDED

[sekhar]

hi guys ,
currently i have been stuck with this ic that is intended for 30W smps application........ can anybody help me with this............
the appication datasheets circuit sems to be correct as it generates 12V but as soon as i give some load it falls and starts oscillating..........
Schematic and application datasheet attached............... in the schematic u will find a red circle wat is this winding used for and if i dont use it wat will happen.......




regards
sekhar

[mastodon]

in the schematic u will find a red circle wat is this winding used for and if i dont use it wat will happen.......

It's for the DC power supply of the controller. If you don't use it, the controller won't work and/or behave unpredictably.

[sekhar]

thanks mastodon ,
that is wat is happening although i have used a simple zener + resistor network to provide power the IC ...... when ever the ic starts switching the power supply voltage drops and the IC shuts down .........and this thing continues in a cyclic order....

regards
sekhar

[mastodon]

So, how stable is the controller's power supply? No issues there?
Does the sense network function; what happens there?
Could you post a schematic of the power supply as you actually built it?

[sekhar]

the sense networks works fine without a load ........... and here is the PS for the IC as i had done it.............





regards
sekhar

[mastodon]

Ok, thanks; any change of posting the rest of the schematic as well?

Note that a zener will need a few mA (say, at least 5 mA) to work reliably; in this case, you supply it with less than 0.2mA, which won't be enough for reliable operation. Not to mention that the controller itself also requires about 1.4mA for operation, so you're effectively starving it. You supply enough for startup, but not for continuous operation, supporting your observations that the controllers keeps restarting.

I'd recommend fixing that first, and then see if any other issues remain. The easiest solution would be to implement the schematic as outlined in your first post, but I take it you use a transformer that doesn't have a separate winding for the Vdd? You _could_ change the 2M resistor into a 50k one , but that'll dissipate over 2W (6,5mA for the zener + the controller's Vdd), so it's not a very efficient or elegant solution. But as long as you use a resistor rated for at least, say, 4W, it should work, sort of.

[sekhar]

hey hi i have made a few changes to the circuit posted above ................. here is the circuit.........
but there r few issues the the transformer makes a weird clicking sound ....... when connected to load the voltage drops........
transformer specs-
EE25
primary - 90 turns(0.3mm @ 700uh)
aux - 18 turns(0.2mm)
secondary - 13 turns(0.5mm)

any help would be appreciated

regards
sekhar

[mastodon]

How much current does the load draw and how much does the voltage drop when the load is connected? What is the frequency of the clicking sound; can you describe it more specifically?

Do you have access to an oscilloscope?

[sekhar]

for glowing a 7W led strip the smps takes almost as 40W ................ the fet becomes hot as hell ....... and the voltage drop is according to the load............ as per say if i am using 4 led stripes then voltage drops from 12.3 to 10V if using 3 strips then it drops to 7V if using 2 strips then 4V and when using 1 strip then 2V. the strips r connected in series each strip consists of 10led connected in parallel........
and the clicking sound is in lower hz as i can make out every time it clicks....

regards
sekhar

[sekhar]

here is the datasheet and the application note of the ic

APPLICATION NOTE OF IC WIY2263.ppt


WIY2263.pdf


regards
sekhar