LTC3542
500mA, 2.25MHz
Synchronous Step-Down
DC/DC Converter
FEATURES
DESCRIPTION
TheLTC®3542isahighefficiencymonolithicsynchronous
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 ideally suited for
single Li-Ion battery-powered applications. 100% duty
cycle provides low dropout operation, extending battery
life in portable systems. The output voltage is adjustable
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High Efficiency: Up to 96%
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High Peak Switch Current: 1000mA
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Low Output Ripple (<20mV Typical)
Burst Mode Operation: Only 26μA
P-P
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Very Low Quiescent Current: Only 26μA
2.5V to 5.5V Input Voltage Range
2.25MHz Constant Frequency Operation
1MHz to 3MHz External Frequency Synchronization
Low Dropout Operation: 100% Duty Cycle
No Schottky Diode Required
Internal Soft-Start Limits Inrush Current
0.6V Reference Allows Low Output Voltages
Shutdown Mode Draws <1μA Supply Current
2% Output Voltage Accuracy
Current Mode Operation for Excellent Line and Load
Transient Response
Overtemperature Protected
Available in 6-Lead 2mm × 2mm DFN and Small TSOT
from 0.6V to V . Internal power switches are optimized
IN
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 is specifically designed to work
well with ceramic output capacitors, achieving very low
output voltage ripple and a small PCB footprint.
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TheLTC3542canbeconfiguredforthepowersavingBurst
Mode® Operation. For reduced noise and RF interference,
the MODE/SYNC pin can be configured for pulse skipping
operation.
APPLICATIONS
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Cellular Telephones
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Wireless and DSL Modems
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Digital Cameras
MP3 Players
, 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.
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PDAs and Other Handheld Devices
Efficiency and Power Loss vs Output Current
TYPICAL APPLICATION
100
90
80
70
60
50
40
30
20
10
0
1000
100
10
V
V
= 3.6V
IN
OUT
= 1.8V
2.2μH
V
OUT
V
IN
1.8V
V
SW
LTC3542
RUN
IN
2.7V TO 5.5V
22pF
C
IN
500mA
10μF
CER
150k
V
FB
C
OUT
75k
MODE/SYNC
GND
10μF
CER
1
3542 TA01a
0.1
1000
0.1
1
10
100
3542 TA01b
OUTPUT CURRENT (mA)
3542fa
1