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TPS92410EVM-002 Board Design Questions

Other Parts Discussed in Thread: TPS92410EVM-002, TPS92410, TPS2410, PMP6023


I have a few questions pertaining to a board design based on the TPS92410EVM-002:

  1. How can I ensure equal current goes to the x3 TPS92410 stages in order to maintain equal brightness on the LEDs?
  2. Is the TPS2410 ADIM pin isolated or does it needs some king of opto isolation? If so, what would you recommend for the 0-10V input dimming isolation?
  3. Can SMT Cermanic caps substitute the through hole electrolytics?

Thank you,

  • Michael:
    1. When the rectified AC input is at the peak, all 3 sections of the LEDs are in series. At that moment, the current through all the LEDs are the same. When the rectified AC input is not at the peak, some LEDs are not driven by the input. Because there is a large capacitor in parallel with the LEDs, the capacitor will maintain that peak current even if those LEDs are not driven by the input . So the currents through all 3 sections of the LEDs are almost equal.
    2. TPS92410 ADIM pin is not isolated. It does not need opto isolation for triac dimming. If the customer wants to use 0-10V dimmer, they can look at the opto isolation circuit used in TI reference design PMP6023.
    3. I do not recommend using ceramic caps to replace those electrolytics. First, it is hard to find high voltage high capacitance ceramic caps. Second, the capacitance of the ceramic cap is usually less than 100% at rated voltage.
    David Zhang
  • Great! Thank you for the quick response.