INPUT CURRENT (mA) LTC3453 Synchronous Buck-Boost High Power White LED Driver FEATURES DESCRIPTIO High Efficiency: 90% Typical Over Entire The LTC 3453 is a synchronous buck-boost DC/DC con- Li-Ion Battery Range verter optimized for driving up to 4 white LEDs at a Wide V Range: 2.7V to 5.5V combined current of up to 500mA from a single Li-Ion IN Up to 500mA Continuous Output Current battery input. The regulator operates in either synchro- Internal Soft-Start nous buck, synchronous boost, or buck-boost mode, Open/Shorted LED Protection depending on input voltage and LED maximum forward LED Current Matching Typically <2% voltage. Optimum efficiency is achieved using a propri- Constant Frequency 1MHz Operation etary architecture that determines which LED requires the Low Shutdown Current: 6A largest forward voltage drop at its programmed current, Overtemperature Protection and regulates the common output rail for lowest dropout. Small Thermally Enhanced 16-Lead (4mm x 4mm) Efficiency of 90% can be achieved over the entire usable QFN Package range of a Li-Ion battery (2.7V to 4.2V). U LED current is programmable to one of four levels (includ- APPLICATIO S ing shutdown) with dual current setting resistors and dual enable pins. In shutdown, the supply current is only 6A. Cell Phones Digital Cameras A high constant operating frequency of 1MHz allows the PDAs use of a small external inductor. The LTC3453 is offered Portable Devices in a low profile (0.75mm) thermally enhanced 16-lead , LTC and LT are registered trademarks of Linear Technology Corporation. (4mm x 4mm) QFN package. All other trademarks are the property of their respective owners. TYPICAL APPLICATIO High Efficiency Torch/Flash LED Driver L1 Torch Mode Efficiency vs V IN 4.7H V IN 100 180 1-CELL 150mA/500mA 2.2F V PV SW1 SW2 V 4.7F IN IN OUT Li-Ion 2.7V to 4.2V 90 160 EFFICIENCY D1 80 140 LED1 LED2 70 120 I 1MHz LED3 IN V C BUCK-BOOST LED4 60 100 EN1 0.1F EN1 (TORCH) I = 150mA LED D1: LUMILEDS LXCL-PWF1 EN2 T = 25C A EN2 (FLASH) L1: VISHAY DALE IDCS-2512 50 80 I SET1 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 EN1 EN2 I LED V (V) 8.25k I IN SET2 1% 0 0 0 (SHUTDOWN) 3453 TA01b LTC3453 3.48k 1 0 150mA 3453 TA01a 1% 0 1 350mA GND GND PGND 1 1 500mA 3453fa 1 LED POWER EFFICIENCY P /P (%) LED IN U ULTC3453 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 LED1 to LED4 Voltage ...... 0.3V to (V + 0.3V) or 6V OUT 16 15 14 13 V , EN1, EN2, C V 1 12 V IN C I , I Voltage .......... 0.3V to (V + 0.3V) or 6V EN1 2 11 EN2 SET1 SET2 IN 17 I 3 10 I LED1 to LED4 Peak Current ................................ 250mA SET1 SET2 LED1 LED4 4 9 Storage Temperature Range .................. 65C to 125C 5 6 7 8 Operating Temperature Range (Note 2) ... 40C to 85C Junction Temperature (Note 3)............................. 125C UF PACKAGE 16-LEAD (4mm 4mm) PLASTIC QFN T = 125C, = 40C/W, = 2.6C/W JMAX JA JC EXPOSED PAD (PIN 17) IS PGND, MUST BE SOLDERED TO PCB ORDER PART NUMBER UF PART MARKING LTC3453EUF 3453 Order Options Tape and Reel: Add TR Lead Free: Add PBF Lead Free Tape and Reel: Add TRPBF Lead Free Part Marking: