LTC3520 Synchronous 1A Buck-Boost and 600mA Buck Converters FEATURES DESCRIPTION n Dual High Ef ciency DC/DC Converters: The LTC 3520 combines 1A buck-boost and 600mA Buck-Boost (V : 2.2V to 5.25V, I = 1A at synchronous buck DC/DC converters in a tiny 4mm OUT OUT V = 3.3V, V 3V) 4mm package. A programmable switching frequency OUT IN Buck (V : 0.8V to V , I = 600mA) allows the ef ciency to be optimized while minimizing OUT IN OUT n 2.2V to 5.5V Input Voltage Range the solution footprint. Both converters feature soft-start n Pin-Selectable Burst Mode Operation and current limit protection. The uncommitted gain block n Uncommitted Gain Block for LDO Controller, Battery can be con gured as an LDO or utilized as a battery-good Good Indication or Sequencing comparator. n Programmable 100kHz to 2MHz Switching Frequency The buck converter is current mode controlled with internal n 55A Total Quiescent Current for Both Converters in synchronous recti cation to improve ef ciency. Pin-select- Burst Mode Operation able Burst Mode operation can be enabled to improve light n Thermal and Overcurrent Protection load ef ciency, or the buck converter can be operated in n <1A Quiescent Current in Shutdown low noise PWM mode for sensitive applications. n 24-Lead 4mm 4mm QFN Package The buck-boost converter provides continuous conduc- tion operation to maximize ef ciency and minimize noise. APPLICATIONS At light loads, use of Burst Mode operation will improve n ef ciency. Portable Media Players n Digital Cameras The LTC3520 provides a <1A shutdown mode and over- n Handheld PCs, PDAs temperature shutdown on both converters. The LTC3520 n GPS Receivers is available in a low pro le (0.75mm) 24-lead 4mm L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks 4mm QFN package. of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 5481178, 6166527, 6304066, 6404251, 6580258. TYPICAL APPLICATION 3.3V at 500mA, 1.8V at 600mA and 1.5V at 200mA Converter Ef ciency vs V IN 100 V IN 4.7H BUCK-BOOST 2.2V TO 22F 5.5V PV PV PV SV SW1A IN1 IN2 IN3 IN I = 150mA OUT 95 V 4.7H SW1B OUT1 V OUT2 3.3V SW2 V OUT1 1.8V 470pF 500mA BUCK 600mA 255k 56pF 1A FOR 10F 27pF 47F 90 V I = 250mA C1 OUT V 3V 1M IN FB2 15k 10k 0.01F 200k 85 FB1 SS2 0.01F 309k LTC3520 54.9k SS1 80 R T V OUT2 PWM1 A OUT V BURST PWM OUT 75 PWM2 1.5V SD3 200mA 33pF 100k 70 SD2 OFF ON 4.7F 2.2 2.7 3.2 3.7 4.2 4.7 5.2 SD1 A IN V (V) PGND1 SGND PGND2 IN 110k 3520 TA01b 3520 TA01 3520fa 1 EFFICIENCY (%)LTC3520 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW PV , PV , PV , SV Voltage ................ 0.3V to 6V IN1 IN2 IN3 IN SW1A, SW1B, SW2 Voltage DC ............................................................ 0.3V to 6V 24 23 22 21 20 19 Pulsed <100ns ............................................ 1V to 7V SV 1 18 FB1 IN Voltage, All Other Pins ................................. 0.3V to 6V A 2 17 SS1 OUT A 3 16 SGND IN Operating Junction Temperature Range 25 R 4 15 V T C1 (Note 2) .................................................. 40C to 125C PWM1 5 14 FB2 Maximum Junction Temperature (Note 5) ............ 125C SD1 6 13 SS2 Storage Temperature Range ..................65C to 150C 7 8 9 10 11 12 UF PACKAGE 24-LEAD (4mm s 4mm) PLASTIC QFN T = 125C, = 37C/W JMAX JA EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3520EUF PBF LTC3520EUF TRPBF 3520 40C to 85C 24-Lead (4mm 4mm) Plastic QFN LTC3520IUF PBF LTC3520IUF TRPBF 3520 24-Lead (4mm 4mm) Plastic QFN 40C to 125C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. *The temperature grade is identi ed by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based nish parts. For more information on lead free part marking, go to: