ZXLD1371

ZXLD1371

Document number: DS35436 Rev. 1 - 2

22 of 42

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February 2012

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RS

1-D =

0.225

GI_ADJ

(Boost and Buck-boost)

Equation 4

This shows that the LED current depends on the ADJ pin voltage, the reference voltage and 3 resistor values (RS, RGI1

and RGI2). It is independent of the input and output voltages.

If the ADJ pin is connected to the REF pin, this simplifies to

0.225

GI_ADJ

(Boost and Buck-boost)

Considering power dissipation and accuracy, it is useful to know how the mean sense voltage varies with input voltage and

other parameters.

GI_ADJ

1-D

(Boost and Buck-boost)

Equation 5

This shows that the sense voltage varies with duty cycle in Boost and Buck-boost configurations.