FEATURES
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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.
Wide Input Voltage Range: 4.5V to 45V
Tolerant of 60V Input Transients
Internal High Side and Low Side Power Switches
No Compensation Required
50mA Output Current
Low Dropout Operation: 100% Duty Cycle
Low Quiescent Current: 12μA
0.8V Feedback Voltage Reference
Adjustable Peak Current Limit
Internal and External Soft-Start
Precise RUN Pin Threshold with Adjustable
Hysteresis
3.3V, 5V and Adjustable Output Versions
Only Three External Components Required for Fixed
Output Versions
Low Profile (0.75mm) 3mm
×
3mm DFN and
Thermally-Enhanced MS8E Packages
APPLICATIONS
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4mA to 20mA Current Loops
Industrial Control Supplies
Distributed Power Systems
Portable Instruments
Battery-Operated Devices
Automotive Power Systems
TYPICAL APPLICATION
5V, 50mA Step-Down Converter
V
IN
5V TO 45V
1μF
V
IN
SW
LTC3642-5
RUN
V
OUT
SS
HYST
I
SET
GND
3642 TA01a
Efficiency and Power Loss vs Load Current
100
95
EFFICIENCY
90
V
OUT
5V
10μF 50mA
EFFICIENCY (%)
POWER LOSS (mW)
V
IN
= 10V
100
150μH
85
80
75
70
65
0.1
POWER LOSS
10
1
1
10
LOAD CURRENT (mA)
0.1
100
3642 TA01b
3642f
1
LINER [ LINEAR TECHNOLOGY ]
