LTC3542_15 Datasheet, PDF (1/16 Pages) Linear Technology – 500mA, 2.25MHz Synchronous Step-Down DC/DC Converter

LTC3542
500mA, 2.25MHz
Synchronous Step-Down
DC/DC Converter
FEATURES
DESCRIPTION
■ _{High Efficiency: Up to 96%}
■ _{High Peak Switch Current: 1000mA}
■ _{Low Output Ripple (<20mVP-P Typical)}
Burst Mode Operation: Only 26μA
■ _{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}
APPLICATIONS
■ _{Cellular Telephones}
■ _{Wireless and DSL Modems}
■ _{Digital Cameras}
■ _{MP3 Players}
■ _{PDAs and Other Handheld Devices}
The LTC^®3542 is a high efficiency 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 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
from 0.6V to V_IN. 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 is specifically designed to work
well with ceramic output capacitors, achieving very low
output voltage ripple and a small PCB footprint.
The LTC3542 can be configured for the power saving Burst
Mode^® Operation. For reduced noise and RF interference,
the MODE/SYNC pin can be configured for pulse skipping
operation.
, 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
2.7V TO 5.5V
C_IN
10μF
CER
V_IN
SW
LTC3542
RUN V_FB
MODE/SYNC
GND
2.2μH
22pF
150k
75k
V_OUT
1.8V
500mA
C_OUT
10μF
CER
3542 TA01a
Efficiency and Power Loss vs Output Current
100
V_IN = 3.6V
90 _{VOUT = 1.8V}
80
70
1000
100
60
50
10
40
30
1
20
10
0
0.1
0.1
1
10
100
1000
OUTPUT CURRENT (mA) 3542 TA01b
3542fa
1