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UCC28810 buck LED Driver

Other Parts Discussed in Thread: UCC28810, TPS92074, LM3444

Dear IT Application engineers,

I searched in all application notes about UCC28810 as constant current buck converter but hopeless i cant find .

i need to design 150W to 50W led driver with universal input voltage AC from  1-3A output current.

1-Is there any problem about using UCC28810 as buck converter ??

2- i have another question if i need to design buck converter without auxiliary inductor (ZCD) can u suggest IC for this for power 50-150W??

  • Hello,

    1:

    The UCC28810 is intended to regulate output voltage.  It can be set up to regulate current however there are some features in the UCC28810 for voltage regulation that are not desireable for regulating current.

    One is Vov, internally the IC detects an overvoltage event if Vfb is 0.190V above Vref, 2.5 volts on the Vsense pin.

    Two is the internal gain change function for fast transient response due to low PFC bandwidth, this is when Vsense is lower than 0.88*Vref or higher than 1.05*Vref.

    A voltage output generally has a fairly low ripple and these two items do not get triggered under normal operating conditions.  A current regulated output such as an LED load can have significant ripple and it will trip either of the above items.  The way around this is to either make sure the LED ripple is low enough or add extra fitlering to the Vsense feedback to keep the threshold from being met.

    2:

    The ZCD pin can get triggered from circuit determining when the buck inductor is at zero energy without the ZCD winding.  Or there are other parts that can be used, TPS92074/75 is intended to be an off-line buck.

     

  • thanks Irwin Nederbragt for your answer.
    I search about TPS92074 it`s control is digital control ,So u know digital control is not efficient like analog .
    second i cant find a high power application note for input 90-277VAC for TPS92074.
    Can u suggest another IC?
  • Hello,The TPS92074 may not be the right solution if 90-277 VAC in your input
    A simple solution without ZCD for a buck could be the LM3444 however you will not have the best line regulation since there is no compensation loop. Perhaps the UCC28810/11 with a circuit to cause ZCD from the switching node may be better.
    Thanks,
  • i will go in UCC28810 design. but i need pspice model for it for orcad simulation or tina simulation.
    the questions are :
    1- can i make constant current buck converter with UCC28810 ?
    2-can i make buck converter power up to 150W(output :3A 35VDC) ?
    3-Can i achieve more than 0.95 power factor ?

    thanks
  • 1-yes, provided you avoid the OVP and gain change on Vsense feedback.

    2-I don't see a reason why not if everything is sized appropriately.  If the main MOSFET is large enough you may want to make sure the UCC28810 gate drive is adequate.  3A times 35V is 105 watts, is the output 50V?

    3-This is really more dependent on the LED stack voltage and input voltage.  The distortion will go up and power factor down as the LED stack rises or the input voltage falls.  This is because of the discontinuity caused by the buck converter.

    Also, how do you plan on getting the LED current feedback to the IC?