LTC3404
1.4MHz High Efficiency
Monolithic Synchronous
Step-Down Regulator
FEATURES
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DESCRIPTIO
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High Efficiency: Up to 95%
Very Low Quiescent Current: Only 10
µ
A
During Operation
600mA Output Current at V
IN
= 3.3V
2.65V to 6V Input Voltage Range
1.4MHz Constant Frequency Operation
Synchronizable from 1MHz to 1.7MHz
Selectable Burst Mode
TM
Operation or
Pulse Skipping Mode
No Schottky Diode Required
Low Dropout Operation: 100% Duty Cycle
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
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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
APPLICATIO S
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Cellular Telephones
Wireless and DSL Modems
Personal Information Appliances
Portable Instruments
Distributed Power Systems
Battery-Powered Equipment
TYPICAL APPLICATIO
V
IN
2.65V
TO 6V
7
10µF***
CER
6
1
2
47pF
SYNC
V
IN
RUN
I
TH
GND V
FB
4
3
SW
5
Efficiency vs Output Load Current
100
95
EFFICIENCY (%)
High Efficiency Step-Down Converter
4.7µH*
20pF
V
OUT
†
3.3V
22µF**
CER
90
85
80
75
LTC3404
887k
280k
3404 TA01
*TOKO D52LC A914BYW-4R7M
**TAIYO-YUDEN CERAMIC JMK325BJ226MM
***TAIYO-YUDEN CERAMIC LMK325BJ106MN
†
V
OUT
CONNECTED TO V
IN
FOR 2.65V < V
IN
< 3.3V
70
0.1
U
V
IN
= 3.6V
V
IN
= 4.2V
V
IN
= 6V
Burst Mode OPERATION
V
OUT
= 3.3V
L = 4.7µH
1
10
LOAD (mA)
100
1000
3404 TA02
U
U
1
LINER [ LINEAR TECHNOLOGY ]
