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INN3165C not works

Posted by: vito_eng on

Hello

I used PI Expert to design a dual output 17W power supply. I designed the PCB and we build a prototype, with transformer that respects software specification.
We tried to turn on the device but it not works: on both outputs we see 0 V (instead of 5.65V and 13V).
We measured the BPP voltage ad it is 5.4V: this means that in Rbias no current flow. According to datasheet, the innoswitch uses an internal current generator to charge the BPP cap to 5 V, then tries to switch the drain terminal and to start up the transformer: something goes wrong during this phase.
Contacting the transformer manufacturer, he confirmed me that the samples were made according to specific.
Somebody can help me?

Thanks

Files

Attachment Size
Design file with PI Expert 1.38 MB

Comments

Submitted by PI-Spark on 07/10/2020

Hi vito_eng,

Thank you for using Power Integrations products.
Yes, during startup, the IC uses an internal regulator to charge BPP to 5V.
A BPP measurement of 5.4V is an indication that there is indeed sufficient bias current going into BPP through Rbias (BPP will be clamped to Vshunt = 5.36V typical).
Can you share with us the actual schematic and PCB layout of this design?
Please also share the measured BPS pin voltage after power on.
Is the behavior you are seeing consistent with multiple boards?

Regards,
PI-Spark