LTC3452 Synchronous Buck-Boost MAIN/CAMERA White LED Driver FEATURES DESCRIPTIO High Efficiency: 85% Over Entire Li-Ion Battery The LTC 3452 is a synchronous buck-boost DC/DC con- Range verter optimized for driving two banks of white LEDs from Wide V Range: 2.7V to 5.5V a single Li-Ion battery input. Five parallel LEDs can be IN Independent MAIN/CAMERA Current Control driven at up to 25mA each in the low power LED bank, Up to 425mA Continuous Output Current while two LEDs can be driven at up to 150mA each (or a Internal Soft-Start single LED at 300mA) in the high power LED bank. The Open/Shorted LED Protection regulator operates in either synchronous buck, synchro- PWM Brightness Control nous boost or buck-boost mode, depending on input LED Current Matching Typically <2.5% voltage and LED maximum forward voltage. Optimum Constant Frequency 1MHz Operation efficiency is achieved by sensing which LED requires the Low Shutdown Current: 6.5A largest forward voltage drop at its programmed current, Overtemperature Protection and regulating the common output rail for lowest dropout. Small Thermally Enhanced 20-Lead Efficiency of 85% can be achieved over the entire usable (4mm 4mm) QFN Package range of a Li-Ion battery (2.7V to 4.2V). U Maximum LED current for each LED display is program- APPLICATIO S mable with a single external resistor. Dual enable pins Cell Phones allow for PWM brightness control in the low power bank Digital Cameras and independent on/off control for the high current bank PDAs (optimal for LED camera flash). In shutdown, the supply Portable Devices current is only 6.5A. , LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. A high constant operating frequency of 1MHz allows the use of a small external inductor. The LTC3452 is offered in a low profile (0.75mm) thermally enhanced 20-lead (4mm 4mm) QFN package. TYPICAL APPLICATIO 5 20mA White LED Display + 200mA Camera Light Driver L 4.7H V IN Torch and Flash Mode Efficiency SINGLE + 4.7F 2.2F D1 Li-Ion CELL 95 V PV SW1 SW2 V IN IN OUT CAM 2.7V TO 4.2V T = 25C A (V V ) I 93 OUT LEDx LEDx LED EFFICIENCY = H1 200mA EN H V I IN IN 91 I LED H2 SETH 89 TORCH MODE AT 100mA D2 6.19k 87 0mA TO D3 85 20mA LED L1 0mA TO D4 83 1MHz V 20mA C LED L2 BUCK/BOOST D5 0mA TO FLASH MODE AT 200mA 81 0.1F 20mA LED L3 0mA TO D6 79 20mA EN L LED L4 77 0mA TO LTC3452 20mA LED 75 I L5 SETL 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 V (V) 10.2k IN 3452 TA01a MAIN DISPLAY LED BACKLIGHT 3452 TA01b GND GND PGND EXPOSED PAD D1: AOT 2015 D2 TO D6: NICHIA NSCW100 L: COILCRAFT DO3314-472 3452f 1 EFFICIENCY (%) U ULTC3452 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) TOP VIEW V , PV , SW1, SW2, V Voltage ........... 0.3V to 6V IN IN OUT LED to LED Voltage ... 0.3V to (V + 0.3V) or 6V L1 L5 OUT LED , LED Voltage ..... 0.3V to (V + 0.3V) or 6V 20 19 18 17 16 H1 H2 OUT V , EN , EN , C L H V 1 V 15 IN C I , I Voltage............ 0.3V to (V + 0.3V) or 6V SETL SETH IN EN EN 2 14 L H LED to LED Current ....................................... 50mA L1 L5 I 3 21 13 I SETL SETH LED , LED Current ....................................... 250mA H1 H2 LED 4 12 LED L1 H2 Operating Temperature Range (Note 2) .. 40C to 85C LED 5 11 GND L2 Junction Temperature (Note 3)............................ 125C 6 7 8 9 10 Storage Temperature Range ................ 65C to 125C UF PACKAGE 20-LEAD (4mm 4mm) PLASTIC QFN T = 125C, = 40C/W JMAX JA EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB ORDER PART NUMBER UF PART MARKING LTC3452EUF 3452 Order Options Tape and Reel: Add TR Lead Free: Add PBF Lead Free Tape and Reel: Add TRPBF Lead Free Part Marking: