LT3942 36V, 2A Synchronous Buck-Boost Converter and LED Driver FEATURES DESCRIPTION n 4-Switch Single Inductor Architecture Allows V The LT 3942 is a monolithic 4-switch synchronous buck- IN boost converter with constant voltage and constant cur- Above, Below or Equal to V OUT n rent regulation, suitable for both voltage regulator and Constant Voltage and Constant Current Regulation n LED driver applications. The part can regulate the out- Proprietary Peak-Buck Peak-Boost Current Mode n put voltage, or input/output current with input voltages 3V to 36V Input Voltage Range above, below, or equal to the output voltage. The propri- n 0V to 36V Output Voltage Range etary peak-buck peak-boost current mode control scheme n 1.5% Output Voltage Regulation allows adjustable and synchronizable 300kHz to 2MHz n 3% Output Current Regulation fixed frequency operation, or internal 25% triangle spread n 5000:1 External and 128:1 Internal PWM Dimming spectrum operation for low EMI. The LT3942 covers 3V to n Open and Short LED Protection with Fault Reporting 36V input and 0V to 36V output with seamless low-noise n 300kHz to 2MHz Fixed Switching Frequency with mode transition. External Frequency Synchronization n Flicker-Free Spread Spectrum for Low EMI For voltage regulator applications, the LT3942 provides n input or output current monitor. For LED driver applica- Available in 28-Lead QFN (4mm 5mm) n tions, it provides current regulation with up to 128:1 inter- AEC-Q100 Qualified for Automotive Applications nal and 5000:1 external PWM dimming using an optional high-side PMOS switch. Fault protection is also provided APPLICATIONS to detect output short-circuit condition and open or short n Voltage Regulator with Accurate Current Limit LED condition. n General Purpose LED Driver All registered trademarks and trademarks are the property of their respective owners. n Automotive and Industrial Lighting TYPICAL APPLICATION 93% Efficient, 12W (12V, 1A) 2MHz Buck-Boost LED Driver 0.1F 0.1F 3.3H Efficiency vs V IN 100 BST1 SW1 SW2 BST2 100m V IN PV PV IN OUT 8V TO 36V 95 V IN BUCK 10F 499k 1M 1M 10F BOOST EN/UVLO FB 90 OVLO 115k 69.8k 34.8k BUCKBOOST LT3942 85 ISP INTV CC ISN 80 1F 100k PWMTG 1A FAULT 75 V ISMON REF V V = 12V LED LED 0.22F I = 1A LED V C 70 0 5 10 15 20 25 30 35 40 1k 12V ANALOG DIM CTRL SS INPUT VOLTAGE (V) 1A PWM DIM PWM 3942 TA01b 22nF LED RP RT 14.3k 2.2nF 2MHz GND SYNC/SPRD 3942 TA01a Rev. B 1 Document Feedback For more information www.analog.com EFFICIENCY (%)LT3942 ABSOLUTE MAXIMUM RATINGS (Note 1) ISPISN ...........................................................1V to 1V PV , V , EN/UVLO ..................................................40V IN IN Operating Junction Temperature (Notes 2, 3) PV , ISP, ISN .........................................................40V OUT LT3942E ............................................. 40C to 125C SW1, SW2 .................................................................40V LT3942J/LT3942H .............................. 40C to 150C BST1, BST2 ...............................................................45V Storage Temperature Range ................... 65C to 150C BST1SW1, BST2SW2, INTV ................................5V CC OVLO, CTRL, FB, PWM, SYNC/SPRD, FAULT ..............5V PIN CONFIGURATION TOP VIEW TOP VIEW 28 27 26 25 24 23 28 27 26 25 24 23 PV 1 22 PV PV 1 22 PV IN OUT IN OUT PV 2 21 PV PV 2 21 IN PV OUT IN OUT V 3 20 PWMTG V 3 20 PWMTG IN IN INTV 4 19 SYNC/SPRD INTV 4 19 SYNC/SPRD CC 29 CC 29 GND GND EN/UVLO 5 18 RT EN/UVLO 5 18 RT OVLO 6 17 V OVLO 6 17 V C C RP 7 16 FB RP 7 16 FB PWM 8 15 SS 8 PWM 15 SS 9 10 11 12 13 14 9 10 11 12 13 14 UFD PACKAGE UFDM PACKAGE 28-LEAD (4mm 5mm) PLASTIC QFN 28-LEAD (4mm 5mm) PLASTIC SIDE WETTABLE QFN = 43C/W, = 3.4C/W = 43C/W, = 3.4C/W JA JC JA JC EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3942EUFD PBF LT3942EUFD TRPBF 3942 28-Lead (4mm x 5mm) Plastic QFN 40C to 125C LT3942JUFD PBF LT3942JUFD TRPBF 3942 28-Lead (4mm x 5mm) Plastic QFN 40C to 150C LT3942HUFD PBF LT3942HUFD TRPBF 3942 28-Lead (4mm x 5mm) Plastic QFN 40C to 150C AUTOMOTIVE PRODUCTS** LT3942JUFDM WPBF LT3942JUFDM WTRPBF 3942 28-Lead (4mm x 5mm) Plastic Side Solderable QFN 40C to 150C Contact the factory for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Tape and reel specifications. Some packages are available in 500 unit reels through designated sales channels with TRMPBF suffix. **Versions of this part are available with controlled manufacturing to support the quality and reliability requirements of automotive applications. These models are designated with a W suffix. Only the automotive grade products shown are available for use in automotive applications. Contact your local Analog Devices account representative for specific product ordering information and to obtain the specific Automotive Reliability reports for thesemodels. Rev. B 2 For more information www.analog.com V SW1 REF CTRL SW1 ISP BST1 ISN BST2 ISMON SW2 FAULT SW2 V SW1 REF CTRL SW1 ISP BST1 ISN BST2 ISMON SW2 FAULT SW2