LTC3542-1_15 Datasheet, PDF (1/16 Pages) Linear Technology – 500mA, 2.25MHz 2.8V Output Synchronous Step-Down DC/DC Converter

LTC3542-1
500mA, 2.25MHz
2.8V Output Synchronous
Step-Down DC/DC Converter
FEATURES
DESCRIPTION
n _{High Efficiency: Up to 96%}
n _{Fixed Output Voltage: 2.8V}
n _{High Peak Switch Current: 1000mA}
n _{Low Output Ripple (<20mVP-P Typical)}
Burst Mode Operation
n _{Very Low Quiescent Current: Only 26μA}
n _{2.5V to 5.5V Input Voltage Range}
n _{2.25MHz Constant Frequency Operation}
n _{1MHz to 3MHz External Frequency Synchronization}
n _{Low Dropout Operation: 100% Duty Cycle}
n _{No Schottky Diode Required}
n _{Internal Soft-Start Limits Inrush Current}
n _{Shutdown Mode Draws <1μA Supply Current}
n _{±2% Output Voltage Accuracy}
n _{Current Mode Operation for Excellent Line and Load}
Transient Response
n _{Overtemperature Protected}
n _{Available in 6-Lead 2mm × 2mm DFN}
APPLICATIONS
n _{Cellular Telephones}
n _{Wireless and DSL Modems}
n _{Digital Cameras}
n _{MP3 Players}
n _{PDAs and Other Handheld Devices}
The LTC^®3542-1 is a high efficiency, fixed output voltage
of 2.8V, monolithic synchronous buck converter using a
constant frequency, current mode architecture. Supply
current during operation is only 26μA, dropping to <1μA in
shutdown. The 2.5V to 5.5V input voltage range makes the
LTC3542-1 ideally suited for single Li-Ion battery-powered
applications. 100% duty cycle provides low dropout opera-
tion, extending battery life in portable systems. Internal
power switches are optimized to provide high efficiency
and eliminate the need for an external Schottky diode.
Switching frequency is internally set at 2.25MHz, allowing
the use of small surface mount inductors and capacitors,
and it can synchronize to an external clock signal with a
frequency range of 1MHz to 3MHz through the MODE/SYNC
pin. The LTC3542-1 is specifically designed to work well
with ceramic output capacitors, achieving very low output
voltage ripple and a small PCB footprint.
The LTC3542-1 can be configured for the power saving
Burst Mode^® Operation. For reduced noise and RF inter-
ference, the MODE/SYNC pin can be configured for pulse
skipping operation.
L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents
including 5481178, 6580258, 6304066, 6127815, 6498466, 6611131, 5994885.
TYPICAL APPLICATION
V_IN
3V TO 5.5V
10μF
V_IN
SW
LTC3542-1
2.2μH
RUN V_OUT
MODE/SYNC
GND
35421 TA01a
V_OUT
2.8V
500mA
C_OUT
10μF
CER
Efficiency and Power Loss vs Output Current
100
1000
90
80
100
70
60
50
10
40
30
20
10
0
0.1
1
V_IN = 3.6V
V_OUT = 2.8V
0.1
1
10
100
1000
LOAD CURRENT (mA) 35421 TA01b
35421f
1