Datasheet LTC3855 (Analog Devices) - 3

LTC3855 orDer inForMaTion
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3855EFE#PBF LTC3855EFE#TRPBF LTC3855FE 38-Lead Plastic TSSOP –40°C to 85°C LTC3855IFE#PBF LTC3855IFE#TRPBF LTC3855FE 38-Lead Plastic TSSOP –40°C to 125°C LTC3855EUJ#PBF LTC3855EUJ#TRPBF LTC3855UJ 40-Lead (6mm × 6mm) Plastic QFN –40°C to 85°C LTC3855IUJ#PBF LTC3855IUJ#TRPBF LTC3855UJ 40-Lead (6mm × 6mm) Plastic QFN –40°C to 125°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ e

lecTrical characTerisTics
The
l
denotes the specifications which apply over the full operating junction temperature range (E-Grade), otherwise specifications are at TA = 25°C. VIN = 15V, VRUN1,2 = 5V unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Main Control Loops
VIN Input Voltage Range 4.5 38 V VOUT Output Voltage Range 0.6 12.5 V VFB1,2 Regulated Feedback Voltage ITH1,2 Voltage = 1.2V (Note 4) l 0.5955 0.600 0.6045 V ITH1,2 Voltage = 1.2V (Note 4), TA = 125°C l 0.594 0.600 0.606 V IFB1,2 Feedback Current (Note 4) –15 –50 nA VREFLNREG Reference Voltage Line Regulation VIN = 4.5V to 38V (Note 4) 0.002 0.02 %/V VLOADREG Output Voltage Load Regulation (Note 4) Measured in Servo Loop; ∆ITH Voltage = 1.2V to 0.7V l 0.01 0.1 % Measured in Servo Loop; ∆ITH Voltage = 1.2V to 1.6V l –0.01 –0.1 % gm1,2 Transconductance Amplifier gm ITH1,2 = 1.2V; Sink/Source 5µA; (Note 4) 2 mmho IQ Input DC Supply Current (Note 5) Normal Mode VIN = 15V 3.5 mA Shutdown VRUN1,2 = 0V 30 50 µA DFMAX Maximum Duty Factor In Dropout, fOSC = 500kHz 94 95 % UVLO Undervoltage Lockout VINTVCC Ramping Down l 3.0 3.2 3.4 V UVLOHYS UVLO Hysteresis 0.6 V VOVL1,2 Feedback Overvoltage Lockout Measured at VFB1,2 l 0.64 0.66 0.68 V ISENSE1,2 Sense Pins Bias Current (Each Channel); VSENSE1,2 = 3.3V l ±1 ±2 µA ITEMP1,2 DCR Tempco Compensation Current VITEMP1,2 = 0.2V l 9 10 11 µA ITK/SS1,2 Soft-Start Charge Current VTK/SS1,2 = 0V l 1 1.2 1.4 µA VRUN1,2 RUN Pin ON Threshold VRUN1, VRUN2 Rising l 1.1 1.22 1.35 V VRUN1,2HYS RUN Pin ON Hysteresis 80 mV VSENSE(MAX) Maximum Current Sense Threshold VFB1,2 = 0.5V, VSENSE1,2 = 3.3V, ILIM = 0V l 25 30 35 mV VFB1,2 = 0.5V, VSENSE1,2 = 3.3V, ILIM = Float l 45 50 55 mV VFB1,2 = 0.5V, VSENSE1,2 = 3.3V, ILIM = INTVCC l 68 75 82 mV TG1, 2 tr TG Transition Time: (Note 6) TG1, 2 tf Rise Time CLOAD = 3300pF 25 ns Fall Time CLOAD = 3300pF 25 ns BG1, 2 tr BG Transition Time: (Note 6) BG1, 2 tf Rise Time CLOAD = 3300pF 25 ns Fall Time CLOAD = 3300pF 25 ns 3855f Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Block Diagram Operation Applications Information Typical Applications Package Description Related Parts