Datasheet LTC3544B (Analog Devices)

LTC3544B Quad Synchronous Step-Down Regulator: 2.25MHz, 300mA, 200mA, 200mA, 100mA FeaTures DescripTion ■
High Efficiency: Up to 95%
The LTC®3544B is a quad, high efficiency, monolithic ■
Four Independent Regulators Provide Up to 300mA,
synchronous buck regulator using a constant frequency,
200mA, 200mA and 100mA Output Current
current mode architecture. The four regulators operate in- ■
2.25V to 5.5V Input Voltage Range
dependently with separate run pins. The 2.25V to 5.5V input ■
2.25MHz Constant Frequency Operation
voltage range makes the LTC3544B well suited for single ■
No Schottky Diodes Required
Li-Ion/polymer battery-powered applications. 100% duty ■
Low Dropout Operation: 100% Duty Cycle
cycle provides low dropout operation, extending battery ■
Pulse Skipping at Low Load for Minimum Ripple
runtime in portable systems. At moderate and low output ■ 0.8V Reference Allows Low Output Voltages load levels PWM pulse skip mode operation provides very ■ Shutdown Mode Draws <1µA Supply Current low output ripple voltage for noise sensitive applications. ■ Current Mode Operation for Excellent Line and Load Switching frequency is internally set to 2.25MHz, al- Transient Response lowing the use of small surface mount inductors and ■ Overtemperature Protected capacitors. ■ Low Profile (3mm × 3mm) 16-Lead QFN Package The internal synchronous switches increase efficiency applicaTions and eliminate the need for external Schottky diodes. Low output voltages are easily supported with the 0.8V feedback ■ Cellular Telephones reference voltage. ■ Personal Information Appliances The LTC3544B is available in a low profile (0.75mm) ■ Wireless and DSL Modems (3mm × 3mm) QFN package. ■ Digital Still Cameras L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear ■ Media Players Technology Corporation. All other trademarks are the property of their respective owners. ■ Portable Instruments Protected by U.S. Patents including 5481178, 6580258, 6304066, 6127815, 6498466, 6611131, 5994885. Typical applicaTion
High Efficiency Quad Step-Down Converter Efficiency vs Load Current, 300mA
V
Channel, All Other Channels Off
IN 2.25V TO 5.5V 4.7µF 100 1 CER VOUT = 1.5V VCC PVIN 90 TA = 25°C 4.7µH RUN200B RUN200A 3.3µH V 80 OUT2 VOUT3 1.5V SW200B SW200A 93.1k 0.8V 70 POWER LOSS (W) V EFFICIENCY 0.1 FB200B VFB200A 4.7µF 4.7µF 60 107k 100k CER CER LTC3544B 50 POWER LOSS 40 EFFICIENCY (%) 3.3µH RUN300 RUN100 10µH 0.01 30 VOUT4 VOUT1 1.8V SW300 SW100 133k 59k 1.2V 20 V V IN = 2.5V FB300 VFB100 V 4.7µF 10 IN = 3.6V 107k GNDA PGND 118k 4.7µF V CER CER 0 IN = 4.3V 0.001 0.0001 0.001 0.01 0.1 1 3544B TA01a LOAD CURRENT (A) 3544B TA01b 3544bfb Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagrams Operation Applications Information Package Description Revision History Related Parts