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LP8863-Q1: Boost UVP

Hirotsugu Kobayashi
Mastermind 9540 points
Part Number: LP8863-Q1

Hi, team.

Please tell me about the function of  VBOOST_UVP.

When RFB1 = 820 kΩ and RFB2 = 100 kΩ, it becomes as follows.
 Vmaxboost = 42.9 V
 Vboost_ovp_Low = 44.8 V
 Vboost_ovp_High = 47.9 V
 Vboost_uvp = 39.9 V

Is the output voltage set between Vboost_uvp and Vmaxboost?

Or is it set below Vboost_uvp?

How to set it when the total VF of LED is Min 30 V, max 42 V.

Best Regards,

  • 0
    TI__Expert 5475 points

    Hi,

    The equations to calculate Vboost_ovp_low, Vboost_ovp_high and Vboost_uvp in the datasheet are calculated when adaptive voltage control is at the maximum output voltage, so they use Isel_max in the datasheet. But in real cases, it is not necessarily Isel_max in the equations. They just use the FB voltage to compare with Vovph, Vovpl and Vuvp to see if the boost works in ovp or uvp condition.

    So when setting the FB resistor divider, just need to make sure the Vmaxboost is higher than the maximum LED string voltage, and Vminboost is lower than the minimum LED string voltage. No need to pay attention to Vboost_uvp.