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TPS92515HV: How to increase efficiency of TPS92515HV

Ambareesh HS
Prodigy 20 points
Part Number: TPS92515HV

Hi,

Using TPS92515HV to drive a single LED with below configuration;

VIN = 48V, VOUT=36V ILED=1.05A, Rsense= 0.174E, VIADJ=2.4V. LED used will be similar to PHILIPS LUMILED - 1208 or CREE - 2520.

We are using Analog dimming. Microcontroller is driving IADJ pin through a PWM output.

With present design we are getting an efficiency of around 93% to 93.5%. Let me know how to increase efficiency to 96%.

  • 0
    TI__Mastermind 25500 points

    Hello,

    To be honest, 93% is really good for those voltage levels with any switching regulator. The AC losses really come into play since they are proportional to VIN^2. So generally the easiest way at higher voltages to increase efficiency is to use a lower switching frequency.

    Your switching frequency already looks to be on the low end, but you could go lower if you really need more efficiency. Otherwise all you can really do it try and get a lower DCR inductor and/or a lower Vf switching diode. That might buy you some efficiency as well. 96% may be difficult to get to at 48V input however.

    Regards,

    Clint

  • 0 in reply to Clinton Jensen
    Prodigy 20 points
    Hello Clint,

    Thanks for suggestions.

    Yes fSW=352kHz.

    If i have to reduce it further, I hope I need to recalculate Rsense, L, so that's a big change.

    Definitely I will look for lower DCR inductor. I hope switching diode you are referring to D303 connected to SW pin?

    Also in PCB inductor L301 little bit far from LED driver because of space constraints, is that causing more loss due to increased loop area?

    Regards,
    Ambareesh
  • 0 in reply to Ambareesh HS
    TI__Mastermind 25500 points

    Hello Ambareesh,

    Yes, I was referring to D303 as the switching diode. If that and a lower DCR inductor do not get you far enough lowering the switching frequency may be the only way to improve the efficiency. I don't think inductor loop area will affect it much, but it could cause noise issues if it gets large enough.

    In any case, if you do need to change the switching frequency there is an excel calculator for this device under the "Tools and Software" tab on the product page. It is not exact but it will get you very close, to the point where you should just need to adjust the value of Roff a little on the bench to get the correct average current.

    Regards,

    Clint