Datasheet LTC3879 (Analog Devices) - 6

LTC3879
TYPICAL PERFORMANCE CHARACTERISTICS Effi ciency vs Input Voltage Frequency vs Input Voltage Frequency vs Load Current
100 420 410 CONTINUOUS MODE 410 95 15A 370 400 90 15A CCM 330 390 DISCONTINUOUS MODE 85 290 380 80 370 250 1A DCM 75 360 210 0A 350 70 170 EFFICIENCY (%) 1A CCM FREQUENCY (kHz) 340 FREQUENCY (kHz) 65 130 V 330 IN = 15V 60 90 VOUT = 1.2V 320 VIN = 15V VIN = 15V 55 SW FREQ = 400kHz V V 310 OUT = 1.2V 50 OUT = 1.2V FIGURE 10 CIRCUIT FIGURE 10 CIRCUIT FIGURE 10 CIRCUIT 50 300 10 4 8 12 16 20 24 28 4 8 12 16 20 24 28 0 2 4 6 8 10 12 14 V V IN (V) IN (V) ILOAD (A) 3879 G26 3879 G10 3879 G11
Current Sense Voltage vs ITH Voltage On-Time vs ION Current Current Limit Foldback
300 10000 140 FIGURE 10 CIRCUIT VRNG = 1V 250 FIGURE 10 CIRCUIT 120 200 100 150 1000 100 80 50 60 ON-TIME (ns) 0 100 VRNG = 0.2V 40 –50 VRNG = 0.5V VRNG = 1.0V CURRENT SENSE THRESHOLD (mV) 20 –100 VRNG = 1.5V VRNG = 2.0V –150 10 MAXIMUM CURRENT SENSE THRESHOLD (mV) 0 0 0.5 1 1.5 2 2.5 1 10 100 0 0.1 0.2 0.3 0.4 0.5 0.6 ITH VOLTAGE (V) ION CURRENT (A) VFB (V) 3879 G13 3879 G12 3879 G14
Maximum VDS Current Sense Threshold vs VRNG Voltage Load Regulation FCM ITH Voltage vs Load Current
300 0 2.5 VIN = 15V 2.3 –0.02 VOUT = 1.2V 250 FIGURE 10 CIRCUIT 2.1 –0.04 1.9 200 –0.06 1.7 (%) 150 –0.08 1.5 OUTV$ VOLTAGE (V) 1.3 –0.10 I TH 100 1.1 VIN = 15V –0.12 VOUT = 1.2V 0.9 FIGURE 10 CIRCUIT 50 –0.14 0.7 CONTINUOUS MODE DISCONTINUOUS MODE MAXIMUM CURRENT SENSE THRESOLD (mV) 0 –0.16 0.5 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 0 5 10 15 0 5 10 15 20 25 V LOAD CURRENT (A) RNG VOLTAGE (V) LOAD CURRENT (A) 3879 G17 3879 G15 3879 G16 3879f 6