LT3579/LT3579-1 ELECTRICAL CHARACTERISTICSThe l denotes the specifications which apply over the full operatingtemperature range, otherwise specifications are at TA = 25°C. VIN = 5V, VSHDN = VIN, VFAULT = VIN unless otherwise noted. (Note 2). PARAMETERCONDITIONSMINTYPMAXUNITS Minimum Input Voltage l 2.3 2.5 V VIN Overvoltage Lockout 16.2 18.7 21.2 V Positive Feedback Voltage l 1.195 1.215 1.230 V Negative Feedback Voltage l 3 9 16 mV Positive FB Pin Bias Current VFB=Positive Feedback Voltage, Current into Pin l 80.5 83.3 85 µA Negative FB Pin Bias Current VFB=Negative Feedback Voltage, Current out of Pin l 81 83.3 85.5 µA Error Amp Transconductance ΔI=10μA 250 µmhos Error Amp Voltage Gain 70 V/V Quiescent Current Not Switching 1.9 2.4 mA Quiescent Current in Shutdown VSHDN = 0V 0 1 µA Reference Line Regulation 2.5V ≤ VIN ≤ 15V 0.01 0.05 %/V Switching Frequency, fOSC RT = 34kΩ l 2.2 2.5 2.8 MHz RT = 432kΩ l 175 200 225 kHz Switching Frequency in Foldback Compared to Normal fOSC 1/6 ratio Switching Frequency Range Free-Running or Synchronizing l 200 2500 kHz SYNC High Level for Sync l 1.3 V SYNC Low Level for Sync l 0.4 V SYNC Clock Pulse Duty Cycle VSYNC = 0V to 2V 20 80 % Recommended Minimum SYNC Ratio 3/4 fSYNC/fOSC Minimum Off-Time 45 nS Minimum On-Time 55 nS SW1 Current Limit At All Duty Cycles (Note 3) l 3.4 4.2 5.1 A SW Current Sharing, ISW2/ISW1 SW1 and SW2 Tied Together 0.78 A/A SW1 + SW2 Current Limit ISW2/ISW1 = 0.78, At All Duty Cycles (Note 3) l 6 7.5 9.4 A Switch VCESAT SW1 and SW2 Tied Together, ISW1 + ISW2 = 5.5A (Note 5) 250 350 mV SW1 Leakage Current VSW1 = 5V 0.01 1 µA SW2 Leakage Current VSW2 = 5V 0.01 1 µA Rev. B For more information www.analog.com 3 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram State Diagram Operation Applications Information Appendix Typical Application Package Description Typical Application Related Parts Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram State Diagram Operation Applications Information Appendix Typical Application Package Description Revision History Typical Application Related Parts
