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Original question:

UCC256303: LL/SS pin voltage

UCC256303: BLK pin

parisaSA
Prodigy 130 points
Part Number: UCC256303

hi all,

without any feedback loop, I just want to see some starting pulese of IC, can it be possible?

I get pules over BLK like this:

can you please tell me why is not stable (3V) ?

Best Regards

  • 0
    TI__Mastermind 27105 points
    Hi parisaSA,

    I would not recommend running this controller open loop. It will cause the controller to push its switching frequency as low as possible which will push the output voltage and resonant capacitor voltage high. BLK is an input pin that should be connected to a resistor divider fed from the input voltage. BLK should not be pulsing like this. If you lift the BLK pin and look at the BLK resistor divider voltage, do you still get this pulsing behavior?

    Best Regards,
    Ben Lough
  • 0 in reply to Benjamin Lough
    TI__Mastermind 27105 points
    Hi Parisa,

    As this conversation has moved to email, I will go ahead and close the E2E thread. Let's continue to discuss over email.

    Best Regards,
    Ben Lough