LT3956 absoluTe MaxiMuM raTings pin conFiguraTion (Note 1) V TOP VIEW IN, ISP, ISN ..80V SW ..84V EN/UVLO (Note 3) ...80V RT SS VMODE PWM V REF CTRL V C 36 35 34 33 32 31 30 INTVCC .. VIN + 0.3V, 8V NC 1 28 ISP PWMOUT ..INTVCC + 0.3V EN/UVLO 2 27 ISN CTRL, PWM, VMODE ..12V INTVCC 3 37 FB ...8V GND GND 4 25 FB V 24 GND C, VREF , SS ..3V RT ..1.5V VIN 6 23 PWMOUT PGND to GND ...±0.5V 38 SW 8 21 SW Operating Junction Temperature Range SW SW 9 20 SW (Note 2) ... –40°C to 125°C NC 10 Maximum Junction Temperature... 125°C 12 13 14 15 16 17 Storage Temperature Range ... –65°C to 125°C Lead Temperature (Soldering, 10 sec) .. 300°C PGND PGND PGND PGND PGND PGND UHE PACKAGE 36-LEAD (5mm s 6mm) PLASTIC QFN TJMAX = 125°C, θJA = 43°C/W, θJC = 5°C/W EXPOSED PAD (PIN 37) IS GND, MUST BE SOLDERED TO PCB EXPOSED PAD (PIN 38) IS SW, MUST BE SOLDERED TO PCB orDer inForMaTion LEAD FREE FINISHTAPE AND REELPART MARKING*PACKAGE DESCRIPTIONTEMPERATURE RANGE LT3956EUHE#PBF LT3956EUHE#TRPBF 3956 36-Lead (5mm × 6mm) Plastic QFN –40°C to 125°C LT3956IUHE#PBF LT3956IUHE#TRPBF 3956 36-Lead (5mm × 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. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ This product is only offered in trays. For more information go to: http://www.linear.com/packaging/ e lecTrical characTerisTics The l denotes the specifications which apply over the full operating temp-erature range, otherwise specifications are at TA = 25°C. VIN = 24V, EN/UVLO = 24V, CTRL = 2V, PWM = 5V, unless otherwise noted.PARAMETERCONDITIONSMINTYPMAXUNITS VIN Minimum Operating Voltage VIN Tied to INTVCC l 4.5 V VIN Shutdown IQ EN/UVLO = 0V 0.1 1 µA EN/UVLO = 1.15V 5 µA VIN Operating IQ (Not Switching) PWM = 0V 1.4 1.7 mA VREF Voltage –100µA ≤ IVREF ≤ 0µA l 1.965 2.00 2.045 V VREF Line Regulation 4.5V ≤ VIN ≤ 80V 0.006 %/V 3956f 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 Application Package Description Typical Application Related Parts