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Issues on initial start up voltage in LNK6776V based circuit

Posted by: pemendra.pardh… on

Dear Power Integration Team,

Our team is working on the development of a power adopter and power backup using LNK6776V.

The power circuit and specs of the utilized transformer are attached here.

-The given circuit is designed for an input voltage of 85V to 265 Vac,

-The startup input voltage is decided 85Vac. However, during the testing, at 13 Vac input, the output obtained 3 Vdc. And with the increasing input voltage, the output voltage increases. And output voltage is regulated at 12 Vdc when the input voltage is 85Vac and more than this.  

But we need an output of 12V at 85Vac or higher than this. Below to 85Vac input, the output must be zero.

To rectify this issue, feedback resistance is increased (with a maintained feedback resistance ratio constant)  to minimize the negative forward pulse current, but the problem does not resolve.

Dear power integration technical team, kindly review the circuit as attached here and provide the solution to resolve the problem.

 

Thanks 

Pemendra Kumar Pardhi

Sr. Power Electronics Design Engineer

 CastNX Pvt. Ltd.  

Files

Attachment Size
FLAMINGO_(iUPS).pdf 424.05 KB
iUPS_20W_TX _Spex.pdf 129.35 KB

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