LTC3642 Datasheet, PDF (1/20 Pages) Linear Technology – High Effi ciency, High Voltage 50mA Synchronous Step-Down Converter

FEATURES
n _{Wide Input Voltage Range: 4.5V to 45V}
n _{Tolerant of 60V Input Transients}
n _{Internal High Side and Low Side Power Switches}
n _{No Compensation Required}
n _{50mA Output Current}
n _{Low Dropout Operation: 100% Duty Cycle}
n _{Low Quiescent Current: 12μA}
n _{0.8V Feedback Voltage Reference}
n _{Adjustable Peak Current Limit}
n _{Internal and External Soft-Start}
n _{Precise RUN Pin Threshold with Adjustable}
Hysteresis
n _{3.3V, 5V and Adjustable Output Versions}
n _{Only Three External Components Required for Fixed}
Output Versions
n _{Low Profile (0.75mm) 3mm × 3mm DFN and}
Thermally-Enhanced MS8E Packages
APPLICATIONS
n _{4mA to 20mA Current Loops}
n _{Industrial Control Supplies}
n _{Distributed Power Systems}
n _{Portable Instruments}
n _{Battery-Operated Devices}
n _{Automotive Power Systems}
LTC3642
High Efficiency, High Voltage
50mA Synchronous
Step-Down Converter
DESCRIPTION
The LTC^®3642 is a high efficiency step-down DC/DC
converter with internal high side and synchronous power
switches that draws only 12μA typical DC supply current
at no load while maintaining output voltage regulation.
The LTC3642 can supply up to 50mA load current and
features a programmable peak current limit that provides
a simple method for optimizing efficiency in lower current
applications. The LTC3642’s combination of Burst Mode^®
operation, integrated power switches, low quiescent cur-
rent, and programmable peak current limit provides high
efficiency over a broad range of load currents.
With its wide 4.5V to 45V input range and internal
overvoltage monitor capable of protecting the part through
60V surges, the LTC3642 is a robust converter suited for
regulating a wide variety of power sources. Additionally,
the LTC3642 includes a precise run threshold and soft-start
feature to guarantee that the power system start-up is
well-controlled in any environment.
The LTC3642 is available in the thermally enhanced
3mm × 3mm DFN and MS8E packages.
L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
5V, 50mA Step-Down Converter
V_IN
5V TO 45V
1μF
V_IN
SW
LTC3642-5
RUN
HYST
V_OUT
SS
I_SET
GND
150μH
3642 TA01a
V_OUT
5V
10μF ^50mA
Efficiency and Power Loss vs Load Current
100
V_IN = 10V
95
100
EFFICIENCY
90
85
10
POWER LOSS
80
75
1
70
65
0.1
1
10
LOAD CURRENT (mA)
0.1
100
3642 TA01b
3642f
1