LM3554TMXSLASHNOPB datasheet(9/47 Pages) TI1

9 / 47 page

LM3554

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SNVS549C – JUNE 2009 – REVISED FEBRUARY 2016

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Typical Characteristics (continued)

VIN = 3.6 V, LEDs are Lumiled PWF-4, COUT = 10 µF, CIN = 4.7 µF, L = FDSE0312-2R2 (2.2 µH, RL = 0.15 Ω), TA = 25°C,

unless otherwise specified.

(1)

The typical curve for Current Limit is measured in closed loop using the Typical Application Circuit by increasing IOUT until the peak

inductor current stops increasing. The value given in Electrical Characteristics is measured open loop and is found by forcing current

into SW until the current limit comparator threshold is reached. Closed loop data appears higher due to the delay between the

comparator trip point and the NFET turning off. This delay allows the closed-loop inductor current to ramp higher after the trip point by

approximately 20 ns × VIN / L.

VLED = 1.5 V

Figure 14. Active (Non-Switching) Supply Current vs VIN

VOUT = 5 V

IOUT = 400 mA

Figure 15. Active (Switching) Supply Current vs VIN

Figure 16. Closed Loop Current Limit vs VIN

(Flash Duration Register Bits [6:5] = 00)(1))

Figure 17. Closed Loop Current Limit vs VIN

(Flash Duration Register Bits [6:5] = 01)(1) )

Figure 18. Closed Loop Current Limit vs VIN

(Flash Duration Register Bits [6:5] = 10)(1))

Figure 19. Closed Loop Current Limit vs VIN

(Flash Duration Register Bits [6:5] = 11)(1))

LM3554TMX/NOPB Fiches technique(PDF) 9 Page - Texas Instruments