LED6000 datasheet(22/49 Pages) STMICROELECTRONICS

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Functional description

LED6000

22/49

DocID027777 Rev 2

Assuming VF = 0.6 V the free-wheeling diode direct voltage, RDCR = 30 m inductor

parasitic resistance, ILIM = IPK = 4 A the peak current limit, RON = 0.25  HS MOS

resistance and TON,MIN = 120 ns minimum HS MOS on duration, the maximum FSW

frequency which avoids the inductor current runaway in case of the output short-circuit and

VIN = 61 V is 801 kHz.

If the programmed switching frequency is higher than the above computed limit, an

estimation of the inductor current in case of the output short-circuit fault is provided by

Equation 5:

Equation 5

The peak current limit threshold (ILIM) can be programmed in the range 0.85 A - 4.0 A by

selecting the proper RILIM resistor, as suggested in Equation 6.

Equation 6

IPK is the default LED6000 current limit in case of RILIM not mounted, as shown in Table 5 on

page 8.

Figure 14. Current limit and programming resistor



DCR

MIN

DCR

LIM















LIM

ILIM





 20

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