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TPS92310: How to TPS92310 fine tune for TRIAC

Jason Chien42
Expert 1180 points
Part Number: TPS92310

Dear Sir:

                Our customer reference PMP6013 to design AC90~130 Vin and DC 21~39 Vout with TRIAC dimming control LED driver. It can turn on 8S LED board , But when we adjust TRIAC( LUTRON CT-603PG) , then it have some flick , Do you have any suggest to us  for Fine tune our TRIAC?

Best Regard

Jason

  • 0
    TI__Mastermind 28655 points

    Hello Jason,

    Do you have a schematic of this design and the output power/current?

    Two main things with triac dimmers are:

    1)  Having enough holding current to keep the triac on

    2)  Making sure the input current doesn't ring too low or even negative at a frequency the triac can turn-off.

    Best way is to look at the input current at different operating points and when it is flickering.  If you get those pictures, schematic and output power/current I can help.

    Regards,

  • 0 in reply to Irwin Nederbragt
    Expert 1180 points

    Dear Sir:

                   Thanks for your reply. Due to we get this schematic from our customer , Can I sent it to your e-mail?  We have tried 2 kind of LED board as 11S/10P and 8S/9P , Then 11/S/10P can normally dimming control through TRIAC , the waveform as picture 1 picture 2  (picture 1 is full turn on and picture 2 is full turn off) , but 8S/9P had some flick as picture 3 and picture 4 (picture 3 is full turn on and picture 4 is turn to flick) , How Can we fine tune our circuits?BTW ,  Below is Spec of our transforme , FYI~

    Channel 1 =Vout

    Channel 2 =Iout

    Channel 3=VCC

    Channel 4 =AC current

    L1  (Primary)  :  58  turns  @    0.25mm       

    L2  (Secondary) :  33 turns@     0.25mm      

    L3  (Aux)  :  25   turns @      0.25mm  

    L1 :    580uH   

    Regards

    Jason

  • 0 in reply to Jason Chien42
    TI__Mastermind 28655 points

    Hi Jason,

    It appears that the TPS92310 is shutting off due to UVLO and turning back on after VCC ramps up.  Either the triac is misfiring causing VCC to drop or VCC is just too low for that LED stack voltage and dimming level.

    Does the LED stack have a large capacitor across it?  Seems like the current ripple is high.

    You can send the schematic to my email.

    Regards,

  • 0 in reply to Irwin Nederbragt
    Expert 1180 points

    Dear Sir:

                    Thanks for your reply. May I have your E-mail address?

    Regards

    Jason

  • 0 in reply to Jason Chien42
    TI__Mastermind 28655 points
    Hello Jason,

    You have contacted me. I'm not sure it the reply is working so I'm going to reply here as well:

    "Hi Jason,

    One thing they can try is to reduce the value of R15. 20 ohms seems like a low value but when you're triac dimming there isn't as much time to recharge the VCC capacitors. If they are trying to make this work over a large output range they may want to increase the VCC winding voltage and add a voltage regulator that consists of a small MOSFET, resistor and zener.

    Regards,"
  • 0 in reply to Irwin Nederbragt
    TI__Mastermind 28655 points

    Hi Jason,

    Increasing the voltage from the bias winding and adding this circuit would prevent the VCC from dropping out.  The MOSFET VDS needs to be higher than the highest bias winding voltage.

    Regards,