LTC3642
High Efficiency, High Voltage
50mA Synchronous
Step-Down Converter
FEATURES
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.
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Wide Input Voltage Range: 4.5V to 45V
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Tolerant of 60V Input Transients
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Internal High Side and Low Side Power Switches
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No Compensation Required
50mA Output Current
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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.
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Low Dropout Operation: 100% Duty Cycle
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Low Quiescent Current: 12μA
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0.8V Feedback Voltage Reference
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Adjustable Peak Current Limit
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Internal and External Soft-Start
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Precise RUN Pin Threshold with Adjustable
Hysteresis
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With its wide 4.5V to 45V input range and internal
overvoltagemonitorcapableofprotectingthepartthrough
60V surges, the LTC3642 is a robust converter suited for
regulating a wide variety of power sources. Additionally,
theLTC3642includesapreciserunthresholdandsoft-start
feature to guarantee that the power system start-up is
well-controlled in any environment.
3.3V, 5V and Adjustable Output Versions
Only Three External Components Required for Fixed
Output Versions
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Low Profile (0.75mm) 3mm × 3mm DFN and
Thermally-Enhanced MS8E Packages
APPLICATIONS
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.
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4mA to 20mA Current Loops
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Industrial Control Supplies
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Distributed Power Systems
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Portable Instruments
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Battery-Operated Devices
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Automotive Power Systems
Efficiency and Power Loss vs Load Current
TYPICAL APPLICATION
100
V
= 10V
IN
95
90
85
80
75
70
65
100
10
1
5V, 50mA Step-Down Converter
EFFICIENCY
150ꢀH
V
OUT
V
IN
V
SW
5V
IN
5V TO 45V
1ꢀF
50mA
LTC3642-5
10ꢀF
POWER LOSS
RUN
HYST
V
OUT
SS
I
SET
GND
3642 TA01a
0.1
100
0.1
1
10
LOAD CURRENT (mA)
3642 TA01b
3642f
1
Linear [ Linear ]
