TNY286 auto restart
Hi,
We have created a flyback supply using TNY286, from 85-265VAC to 15VDC. No bias winding, feedback is optical. Our power usage is only 1.5W, so we are using a small flyback transformer. The tricky point is however that we have in total 8000uF capacitors on the 15V, so regulation is achieved only after around 200ms. Because of this the TNY286 auto restart feature kicks in, several attempts are required before reaching the 15V level. Once there, all is working fine. If the input voltage drops below around 200VAC, the auto restart sequence goes on forever, the discharge of the capacitors during the 2.5s pause is more than the charging during the 64ms.
Is there a way to increase the auto restart timeout? Is it maybe possible to disable the feature completely? Or do you have any other suggestion to solve this?
Regards
Janos
Comments
Hi,
I have attached our schematics and transformer data. At the moment the PCB is experimental, with wires for some connections.
Regards
Janos
| Attachment | Size |
|---|---|
| Supply.pdf | 249.51 KB |
Hi,
The output cap used is too large for the output voltage to settle before AR kicks in.
We do not have options to change this AR timer or disable it. You could try reducing the output capacitor to ~1000uF to eliminate AR.
Best Regards,
PI-Kryten
Hi Kryten,
Thanks for your analysis. Given that we need the power reserve provided by the capacitors, what would be in your opinion the way forward? We would need a bigger transformer or another IC? Maybe both?
Regards
Janos
Hi,
If reducing the output capacitor is not an option, you could try using a high Ilim device such as InnoSwitch.
Best Regards,
PI-Kryten
Hi,
Thank you for considering Power Integrations for your solution.
Could you please share more details of your design such as the schematic, PCB design and transformer documentation?
Best Regards,
PI-Kryten