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How to select the inductor for an LED driver application in boost to ground topology

How to select the inductor for an LED driver application in boost to ground topology

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How to select the inductor for an LED driver application in boost to ground topology

Two equations are needed to choose the correct value of inductor for the DC-DC

  • The first equation determinates the minimum inductance Lmin as a function of the input and output voltages VIN and VOUT as well as the switching frequency fsw and the ripple current ΔIL:

Lmin ≥  (VOUT-VIN)/VOUT * VIN/(ΔIL * fsw)

  • The second equation gives the minimum inductance to prevent discontinuous conduction mode (DCM) as a function of the maximum input voltage VIN_MAX and the minimum input current IIN_MIN:

Lmin ≥  (VOUT-VIN)/VOUT * VIN_MAX/(2*IIN_MIN * fsw)

For further information check the TLD5099EP datasheet, while more information on how to design a proper solution can be found in the Z8F66213399 DRL driver with TLD5099EP B2G-AN application note

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