Datasheet LT3975 (Analog Devices) - 5

LT3975
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. Thermal Derating Switch Current Limit Switch Current Limit
3.0 7 7.0 VIN = 12V 30% DUTY CYCLE VOUT = 5V 6.5 2.5 6 I-GRADE 6.0 5 2.0 H-GRADE 5.5 4 1.5 5.0 LIMITED BY MAXIMUM 3 JUNCTION TEMPERATURE 4.5 LOAD CURRENT (A) 1.0 θ CURRENT LIMIT (A) CURRENT LIMIT (A) JA = 40°C/W 2 4.0 0.5 1 3.5 0 0 3.0 –50 –25 0 25 50 75 100 125 150 0 0.2 0.4 0.6 0.8 1 –55 –25 5 35 65 95 125 155 TEMPERATURE (°C) DUTY CYCLE TEMPERATURE (°C) 3975 G10 3975 G11 3975 G12
Current Limit Foldback Soft-Start Switch VCESAT
6 6 250 30% DUTY CYCLE 30% DUTY CYCLE V VFB = 1V SS = 3V 5 5 200 VFB = 0V 4 4 150 (mV) 3 3 V CESAT 100 CURRENT LIMIT (A) 2 CURRENT LIMIT (A) 2 50 1 1 0 0 0 0 0.2 0.4 0.6 0.8 1.0 1.2 0 0.5 1 1.5 2 2.5 0 0.5 1 1.5 2.0 2.5 3.0 FB PIN VOLTAGE (V) SS PIN VOLTAGE (V) SWITCH CURRENT (A) 3975 G13 3975 G14 3975 G15
BOOST Pin Current Minimum On-Time Minimum Off-Time
50 180 200 VSYNC = 0V VSYNC = 0V 45 170 fSW = 2MHz 190 fSW = 2MHz 160 40 180 150 35 140 170 30 130 160 LOAD = 1A 25 120 150 LOAD = 2.5A 20 110 140 100 LOAD = 1A 15 130 MINIMUM ON-TIME (ns) LOAD = 2.5A BOOST PIN CURRENT (mA) 90 MINIMUM OFF-TIME (ns) 10 80 120 5 70 110 0 60 100 0 0.5 1 1.5 2 2.5 3 –55 –25 5 35 65 95 125 155 –55 –25 5 35 65 95 125 155 SWITCH CURRENT (A) TEMPERATURE (°C) TEMPERATURE (°C) 3975 G16 3975 G17 3975 G18 3975f 5 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION ELECTRICAL CHARACTERISTICS TYPICAL PERFORMANCE CHARACTERISTICS PIN FUNCTIONS BLOCK DIAGRAM OPERATION APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION TYPICAL APPLICATION RELATED PARTS