Datasheet LTC3404 (Analog Devices)

LTC3404 1.4MHz High Efficiency Monolithic Synchronous Step-Down Regulator
U FEATURES DESCRIPTIO
■
High Efficiency: Up to 95%
The LTC®3404 is a high efficiency monolithic synchro- ■
Very Low Quiescent Current: Only 10
μ
A
nous buck regulator using a constant frequency, current
During Operation
mode architecture. Supply current during operation is ■
600mA Output Current at VIN = 3.3V
only 10μA and drops to < 1μA in shutdown. The 2.65V to ■
2.65V to 6V Input Voltage Range
6V input voltage range makes the LTC3404 ideally suited ■
1.4MHz Constant Frequency Operation
for single Li-Ion battery-powered applications. 100% duty ■
No Schottky Diode Required
cycle provides low dropout operation, extending battery ■
Low Dropout Operation: 100% Duty Cycle
life in portable systems. ■ Synchronizable from 1MHz to 1.7MHz Switching frequency is internally set at 1.4MHz, allowing ■ Selectable Burst Mode® Operation or the use of small surface mount inductors and capacitors. Pulse Skipping Mode For noise sensitive applications the LTC3404 can be ■ 0.8V Reference Allows Low Output Voltages ■ Shutdown Mode Draws < 1μA Supply Current externally synchronized from 1MHz to 1.7MHz. Burst ■ ±2% Output Voltage Accuracy Mode operation is inhibited during synchronization or ■ Current Mode Control for Excellent Line and when the SYNC/MODE pin is pulled low, preventing low Load Transient Response frequency ripple from interfering with audio circuitry. ■ Overcurrent and Overtemperature Protected The internal synchronous switch increases efficiency and ■ Available in 8-Lead MSOP Package eliminates the need for an external Schottky diode. Low
U
output voltages are easily supported with the 0.8V feed-
APPLICATIO S
back reference voltage. The LTC3404 is available in a ■ Cellular Telephones space saving 8-lead MSOP package. ■ Wireless and DSL Modems For higher input voltage (11V abs max) applications, refer ■ Personal Information Appliances to the LTC1877 data sheet. ■ Portable Instruments ■ Distributed Power Systems , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation. ■ Battery-Powered Equipment All other trademarks are the property of their respective owners.
U TYPICAL APPLICATIO Efficiency vs Output Load Current
100 VIN = 3.6V
High Efficiency Step-Down Converter
95 4.7 V μH* IN † V 7 5 VOUT 90 IN = 4.2V 2.65V SYNC SW 3.3V 20pF V TO 6V 10μF*** 6 IN = 6V V CER IN LTC3404 22μF** 85 1 RUN CER 2 3 887k EFFICIENCY (%) I V 80 TH FB GND 47pF 4 280k 75 Burst Mode OPERATION 3404 TA01 VOUT = 3.3V L = 4.7μH *TOKO D52LC A914BYW-4R7M 70 **TAIYO-YUDEN CERAMIC JMK325BJ226MM 0.1 1 10 100 1000 ***TAIYO-YUDEN CERAMIC LMK325BJ106MN † LOAD (mA) VOUT CONNECTED TO VIN FOR 2.65V < VIN < 3.3V 3404 TA02 3404fb 1