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TPS92518HV-Q1: Can TPS92518-Q1 use for headlight of DLP scheme

Meng Liu
Intellectual 1765 points
Part Number: TPS92518HV-Q1
Other Parts Discussed in Thread: TPS92518-Q1, LM3409-Q1, LM3409, TPS92518

Hi Expert

My customer want to use TPS92518-Q1 for headlight DLP scheme. but in our reference design that used LM3409-Q1.

DLP have the TR2 request as below, that request Tr2,Tr1<2us. the request detail show in:https://e2e.ti.com/support/power-management-group/power-management---internal/f/power-management---internal-forum/1089872/lm3409hv-q1-lm3409hv-q1-question-in-headlight-of-dlp-scheme?tisearch=e2e-sitesearch&keymatch=%252520user%25253A468035#

my question is: can TPS92518-Q1 satisfy 2us reequipment and can use in headlight of DLP scheme? 

  • 0
    TI__Expert 3180 points

    Hello,

    Generally this will depend on the choice of external components if you are implementing dimming by PWM pin. The inductor and input/output voltage along with the current set point will determine the rise and fall times, according to the basic equation (Vin-Vled)/L = Iled/Tr (edit: equation corrected)

    If you implement shunt FET dimming, then the Tr and Tf depends on how you drive the external shunt FET. Either way LM3409 and TPS92518 will perform similarly, and in both cases this is not dependent to the first order on the device.

    Thanks

  • 0 in reply to Shashank Kulkarni
    TI__Intellectual 1765 points

    Hi 

    thanks for your reply.

    could you please share the Tr data in EVM ?

    ignore output current, EVM whether satisfy 2us? 

  • 0 in reply to Meng Liu
    TI__Expert 3180 points

    Hi,

    You cannot ignore output current. As I told you, the rise time (when output capacitor is close to 0) is a direct function of Vin, Vled, Iled, L. It is a simple inductor volt-second equation. I got the equation wrong in my previous post, which I will correct. The equation is (Vin-Vled)/L = Iled/Tr

    The EVM has a large inductor, so my guess is that it will probably not be able to do 2us Tr for typical situations. 

    However as I also said in the last post, the shunt FET dimming method can achieve 2usec. The EVM does support shunt dimming. The rise time will be a function of how fast the customer drives the shunt FET.