Datasheet LTC3808 (Analog Devices) - 4

LTC3808
W U TYPICAL PERFOR A CE CHARACTERISTICS TA = 25
°
C unless otherwise noted. Maximum Current Sense Voltage Efficiency vs Load Current Efficiency vs Load Current vs ITH Pin Voltage
100 100 100 FIGURE 11 CIRCUIT V FIGURE 11 CIRCUIT OUT = 2.5V Burst Mode OPERATION 95 95 VIN = 5V, VOUT = 2.5V (ITH RISING) 80 Burst Mode OPERATION V 90 (I 90 OUT = 3.3V TH FALLING) 85 FORCED CONTINUOUS BURST MODE 60 MODE 85 V 80 (SYNC/MODE = PULSE SKIPPING OUT = 1.2V V MODE 80 75 IN) FORCED 40 V CONTINUOUS 75 OUT = 1.8V 70 EFFICIENCY (%) EFFICIENCY (%) (SYNC/MODE = 0V) 20 65 CURRENT LIMIT (%) 70 60 0 65 PULSE SKIPPING SYNC/MODE = VIN 55 (SYNC/MODE = 0.6V) VIN = 5V 60 50 –20 1 10 100 1k 10k 1 10 100 1k 10k 0.5 1 1.5 2 LOAD CURRENT (mA) LOAD CURRENT (mA) ITH VOLTAGE (V) 3808 G01 3808 G02 3808 G03
Load Step (Burst Mode Load Step (Forced Continuous Operation) Mode) Load Step (Pulse Skipping Mode)
VOUT VOUT VOUT 200mV/DIV 200mV/DIV 200mV/DIV AC COUPLED AC COUPLED AC COUPLED IL IL IL 2A/DIV 2A/DIV 2A/DIV 100 3808 G04 3808 G05 3808 G06 µs/DIV 100µs/DIV 100µs/DIV VIN = 3.3V VIN = 3.3V VIN = 3.3V VOUT = 1.8V VOUT = 1.8V VOUT = 1.8V ILOAD = 300mA TO 3A ILOAD = 300mA TO 3A ILOAD = 300mA TO 3A SYNC/MODE = VIN SYNC/MODE = 0V SYNC/MODE = VFB FIGURE 11 CIRCUIT FIGURE 11 CIRCUIT FIGURE 11 CIRCUIT
Start-Up with Internal Soft-Start Start-Up with External Soft-Start (TRACK/SS = VIN) (CSS = 10nF)
VOUT VOUT 1.8V 1.8V 500mV/DIV 500mV/DIV 200 3808 G07 3808 G08 µs/DIV 1ms/DIV VIN = 4.2V VIN = 4.2V RLOAD = 1Ω RLOAD = 1Ω FIGURE 11 CIRCUIT FIGURE 11 CIRCUIT 3808f 4