Datasheet LTC3858 (Analog Devices) - 5

LTC3858
TYPICAL PERFORMANCE CHARACTERISTICS Effi ciency and Power Loss vs Output Current Effi ciency vs Output Current
100 10000 100 FIGURE 12 CIRCUIT 90 V 90 IN = 12V VIN = 5V V 80 OUT = 3.3V 1000 80 POWER LOSS (mW) 70 70 VIN = 12V 60 100 60 50 50 Burst Mode 40 OPERATION 10 40 EFFICIENCY (%) PULSE- EFFICIENCY (%) 30 30 SKIPPING 20 MODE 1 20 FORCED 10 CONTINUOUS 10 VOUT = 3.3V MODE FIGURE 12 CIRCUIT 0 0.1 0 0.0001 0.001 0.01 0.1 1 10 0.0001 0.001 0.01 0.1 1 10 OUTPUT CURRENT (A) OUTPUT CURRENT (A) 3858 G01 3858 G02
Load Step Effi ciency vs Input Voltage Load Step (Burst Mode Operation) (Forced Continuous Mode)
98 FIGURE 12 CIRCUIT 96 VOUT = 3.3V I V V OUT = 4A OUT OUT 94 100mV/DIV 100mV/DIV AC- AC- 92 COUPLED COUPLED 90 88 EFFICIENCY (%) 86 IL I 2A/DIV L 2A/DIV 84 82 80 0 5 10 15 20 25 30 35 40 20μs/DIV 3858 G04 VOUT = 3.3V 20μs/DIV 3858 G05 VOUT = 3.3V INPUT VOLTAGE (V) FIGURE 12 CIRCUIT FIGURE 12 CIRCUIT 3858 G03
Load Step (Pulse-Skipping Mode) Inductor Current at Light Load Soft-Start
VOUT FORCED V 100mV/DIV OUT2 CONTINUOUS 2V/DIV AC- MODE COUPLED Burst Mode VOUT1 OPERATION 2V/DIV 2A/DIV IL 2A/DIV PULSE- SKIPPING MODE 20μs/DIV 3858 G06 VOUT = 3.3V 2μs/DIV 3858 G07 VOUT = 3.3V 20ms/DIV 3858 G08 FIGURE 12 CIRCUIT ILOAD = 200μA FIGURE 12 CIRCUIT FIGURE 12 CIRCUIT 3858fc 5