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Why have an Auto-Restart feature?

Posted by: BobM on Sun, 05/02/2021

The reason I ask is that I need to charge a large capacitor that is used for energy storage in the event of a loss of power.  I would like to use the TNY286 in my 13 watt design.  Is this feature needed because there is an overheat problem in the device if it runs for too long?  If not and it is only there as a feature then maybe I can design around it (somehow bring the enable/undervoltage pin low every 60 ms or so).

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Submitted by PI-BERJ on Fri, 05/07/2021

Hi BobM,

The auto-restart is there to protect TNY286 from abnormal conditions e.g. overload, output short, open loop, etc. Besides the fact that tinkering with the enable/undervoltage pin may disable auto-restart protection, this is also not advised as this is where TNY286 achieves closed-loop operation.

Is overheating the reason for the auto-restart, meaning the computed junction temperature is ~142 C? This could be a efficiency or heatsinking issue. If possible, can you share the design details i.e. input/output requirements, schematics, PIExpert spreadsheet, transformer design, layout, etc.?