LT3999 ELECTRICALCHARACTERISTICS The l denotes the specifications which apply over the full operatingtemperature range, otherwise specifications are at TA = 25°C. VIN = 15V PARAMETERCONDITIONSMINTYPMAXUNITSInput Supply and Shutdown VIN Minimum Operating Voltage l 2.7 V VIN Overvoltage Lockout Internal, Rising l 36 40 42 V VIN Supply Current (Note 3) 4.3 mA VIN Shutdown Current VUVLO = 0.3V 0.1 1 μA UVLO Threshold (Rising) l 1.15 1.25 1.35 V UVLO Hysteresis 125 mV UVLO Pin Current VUVLO = 1.25V 10 100 nA OVLO/DC Threshold (Rising) l 1.15 1.25 1.35 V OVLO/DC Hysteresis 125 mV OVLO/DC Pin Current VOVLO/DC = 1.25V 10 100 nA Power Switches (SWA, SWB) Switch Saturation Voltage ISW = 1A 350 mV Switch Current Limit Internal Default l 1.0 1.4 1.7 A Non Overlap Time 70 ns Switch Base Drive Current ISW = 1A 35 mA Oscillator/Sync Switching Frequency RT = 316k 50 kHz RT = 49.9k l 280 300 320 kHz RT = 12.1k 1000 kHz Synchronization Frequency Range 100 1000 kHz SYNC Voltage Threshold 1.5 V SYNC Pin Input Resistance 200 kΩ ILIM/SS SWA and SWB Current Limit RILIM/SS = 43.2k l 0.4 0.5 0.6 A ILIM/SS Pin Current 10 μA Duty Cycle Switch Duty Cycle OVLO/DC = 0.8V, RDC = 24.3k, RT = 49.9k 20 % OVLO/DC = 0.612V, RDC = 24.3k, RT = 49.9k l 22 25 30 % OVLO/DC = 0.3V, RDC = 24.3k, RT = 49.9k 48 % Note 1: Stresses beyond those listed under Absolute Maximum Ratings Note 3: Supply current specification does not include switch drive may cause permanent damage to the device. Exposure to any Absolute currents. Actual supply currents will be higher. Maximum Rating condition for extended periods may affect the device reliability and lifetime. Note 2: The LT3999E is guaranteed to meet performance specifications from 0°C to 125°C junction temperature. Specifications over the –40°C to 125°C operating junction temperature range are assured by design, characterization, and correlation with statistical process controls. The LT3999I Is guaranteed over the –40°C to 125°C operating junction temperature range. The LT3999H is guaranteed over the full –40°C to 150°C operating junction temperature range. The LT3999MP is 100% tested and guaranteed over the –55°C to 150°C junction temperature range. High junction temperatures degrade operating lifetimes; operating lifetime is derated for junction temperatures greater than 125°C. 3999fa For more information www.linear.com/LT3999 3 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Typical Application Related Parts