LTC3522 Synchronous 400mA Buck-Boost and 200mA Buck Converters FEATURES DESCRIPTION Dual High Ef ciency DC/DC Converters: The LTC 3522 combines a 400mA buck-boost DC/DC con- Buck-Boost (V : 2.2V to 5.25V, I : 400mA verter with a 200mA synchronous buck DC/DC converter in OUT OUT for V > 3V, V = 3.3V) a tiny 3mm 3mm package. The 1MHz switching frequency IN OUT Buck (V : 0.6V to V , I : 200mA) minimizes the solution footprint while maintaining high OUT IN OUT 2.4V to 5.5V Input Voltage Range ef ciency. Both converters feature internal soft-start and Pin Selectable Burst Mode Operation compensation, simplifying the design process. 25A Total Quiescent Current for Both Converters in The buck converter is current mode controlled and utilizes Burst Mode Operation an internal synchronous recti er for high ef ciency. The Independent Power Good Indicator Outputs buck converter supports 100% duty cycle operation to Integrated Soft-Start extend battery life. If the PWM pin is held low, the buck Thermal and Overcurrent Protection converter automatically transitions from Burst Mode opera- <1A Quiescent Current in Shutdown tion to PWM mode. With the PWM pin held high, the buck Small 0.75mm 3mm 3mm QFN Package converter remains in low noise, 1MHz PWM mode. APPLICATIONS The buck-boost converter provides continuous conduc- tion operation to maximize ef ciency and minimize noise. Flash-Based MP3 Players At light loads, the buck-boost converter can be placed in Medical Instruments Burst Mode operation to improve ef ciency and reduce Digital Cameras no-load standby current. PDAs, Handheld PCs The LTC3522 provides a 1A shutdown mode, overtem- Personal Navigation Devices perature shutdown and current limit protection on both , LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. converters. The LTC3522 is available in a 16-pin low pro le Protected by U.S. Patents, including 6404251 and 6166527. 3mm 3mm QFN package. TYPICAL APPLICATION Ef ciency vs V IN 100 BUCK-BOOST 98 V IN I = 100mA OUT 2.4V TO 4.2V 96 + V = 3.3V OUT Li-Ion 4.7F 94 L1 L2 PV PV 8.2H IN1 IN2 4.7H 92 BUCK V OUT2 90 I = 100mA 1.8V SW2 SW1A OUT 88 V = 1.8V 200mA OUT 6.8F SW1B V 137k OUT1 12pF 86 LTC3522 3.3V 84 FB2 V 300mA OUT1 82 (400mA 1M 4.7F SHDN2 68.1k ON 80 V > 3V) IN OFF 78 SHDN1 FB1 76 PGOOD2 432k PWM 74 BURST PWM PGOOD1 72 70 PGND1 GND PGND2 4.4 3522 TA01a 2.4 3.4 5.4 L1: COILCRAFT MSS6132-8.2H V (V) IN L2: COILCRAFT MSS6132-4.7H 3522 TA01b 3522fa 1 EFFICIENCY (%)LTC3522 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW PV , PV Voltage .................................... 0.3V to 6V IN1 IN2 SW1A, SW1B, SW2 Voltage 16 15 14 13 DC ............................................................0.3V to 6V FB2 1 12 V OUT1 Pulsed < 100ns ........................................... 1V to 7V PWM 2 11 SW1A Voltage, All Other Pins ................................. 0.3V to 6V 17 GND 3 10 SW1B Operating Temperature Range (Note 2) ... 40C to 85C PGOOD2 4 9 PGND2 Maximum Junction Temperature (Note 5) ............ 125C 5 6 7 8 Storage Temperature Range ................... 65C to 125C UD PACKAGE 16-LEAD (3mm 3mm) PLASTIC QFN T = 125C, = 68C/W JMAX JA EXPOSED PAD (PIN 17) IS GND AND MUST BE SOLDERED TO PCB GROUND ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3522EUD PBF LTC3522EUD TRPBF LCRQ 16-Lead (3mm 3mm) Plastic QFN 40C to 85C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based nish parts. For more information on lead free part marking, go to: