LTC3404IMS8 Datasheet, PDF (1/16 Pages) Linear Technology – 1.4MHz High Efficiency Monolithic Synchronous Step-Down Regulator

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