POWER LOSS (mW)
LTC3642
High Efficiency, High Voltage
50mA Synchronous
Step-Down Converter
FEATURES DESCRIPTION
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Wide Input Voltage Range: 4.5V to 45V The LTC 3642 is a high efficiency, high voltage step-down
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Tolerant of 60V Input Transients DC/DC converter with internal high side and synchronous
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Internal High Side and Low Side Power Switches power switches that draws only 12A typical DC sup-
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No Compensation Required ply current at no load while maintaining output voltage
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50mA Output Current regulation.
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Low Dropout Operation: 100% Duty Cycle
The LTC3642 can supply up to 50mA load current and
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Low Quiescent Current: 12A
features a programmable peak current limit that provides
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0.8V Feedback Voltage Reference
a simple method for optimizing efficiency in lower current
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Adjustable Peak Current Limit
applications. The LTC3642s combination of Burst Mode
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Internal and External Soft-Start
operation, integrated power switches, low quiescent cur-
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Precise RUN Pin Threshold with Adjustable
rent, and programmable peak current limit provides high
Hysteresis
efficiency over a broad range of load currents.
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3.3V, 5V and Adjustable Output Versions
n With its wide 4.5V to 45V input range and internal
Only Three External Components Required for Fixed
overvoltage monitor capable of protecting the part through
Output Versions
n 60V surges, the LTC3642 is a robust converter suited for
Low Profile (0.75mm) 3mm 3mm DFN and
regulating a wide variety of power sources. Additionally,
Thermally-Enhanced MS8E Packages
the LTC3642 includes a precise run threshold and soft-start
feature to guarantee that the power system start-up is
APPLICATIONS
well-controlled in any environment.
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4mA to 20mA Current Loops
The LTC3642 is available in the thermally enhanced
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Industrial Control Supplies
3mm 3mm DFN and MS8E packages.
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Distributed Power Systems
n L, LT, LTC, LTM, Burst Mode, Linear Technology, and the Linear logo are registered trademarks
Portable Instruments
and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the
n
Battery-Operated Devices property of their respective owners.
n
Automotive Power Systems
Efficiency and Power Loss vs Load Current
TYPICAL APPLICATION
100
V = 10V
IN
95 100
5V, 50mA Step-Down Converter
EFFICIENCY
90
150H
V
OUT
V
IN
V SW 5V
IN 85 10
5V TO 45V
50mA
LTC3642-5
1F 10F
POWER LOSS
RUN V
OUT 80
HYST SS
I
75 1
SET
GND
70
3642 TA01a
65 0.1
0.1 1 10 100
LOAD CURRENT (mA)
3642 TA01b
3642fc
1
EFFICIENCY (%)LTC3642
ABSOLUTE MAXIMUM RATINGS (Note 1)
V Supply Voltage ..................................... 0.3V to 60V Operating Junction Temperature Range
IN
SW Voltage (DC) ........................... 0.3V to (V + 0.3V) (Note 2) ..................................................40C to 125C
IN
RUN Voltage .............................................. 0.3V to 60V Storage Temperature Range ...................65C to 150C
HYST, I , SS Voltages ............................... 0.3V to 6V Lead Temperature (Soldering, 10 sec)
SET
V ............................................................... 0.3V to 6V MS8E ................................................................ 300C
FB
V (Fixed Output Versions) ....................... 0.3V to 6V
OUT
PIN CONFIGURATION
TOP VIEW
TOP VIEW
SW 1 8 GND
SW 1 8 GND
V 2 7 HYST
IN 9
V 2 9 7 HYST
IN
GND
GND
I 3 6 V /V I V /V
SET OUT FB 3 6
SET OUT FB
SS 4 5 RUN
SS RUN
4 5
MS8E PACKAGE
8-LEAD PLASTIC MSOP
DD PACKAGE
T = 125C, = 40C/W, = 5-10C/W
JMAX JA JC
8-LEAD (3mm 3mm) PLASTIC DFN
EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB
T = 125C, = 43C/W, = 3C/W
JMAX JA JC
EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3642EMS8E#PBF LTC3642EMS8E#TRPBF 8-Lead Plastic MSOP 40C to 125C
LTDTH
LTC3642EMS8E-3.3#PBF LTC3642EMS8E-3.3#TRPBF 8-Lead Plastic MSOP 40C to 125C
LTDYN
LTC3642EMS8E-5#PBF LTC3642EMS8E-5#TRPBF 8-Lead Plastic MSOP 40C to 125C
LTDYQ
LTC3642IMS8E#PBF LTC3642IMS8E#TRPBF LTDTH 8-Lead Plastic MSOP 40C to 125C
LTC3642IMS8E-3.3#PBF LTC3642IMS8E-3.3#TRPBF 8-Lead Plastic MSOP 40C to 125C
LTDYN
LTC3642IMS8E-5#PBF LTC3642IMS8E-5#TRPBF LTDYQ 8-Lead Plastic MSOP 40C to 125C
LTC3642EDD#PBF LTC3642EDD#TRPBF 8-Lead (3mm 3mm) Plastic DFN 40C to 125C
LDTJ
LTC3642EDD-3.3#PBF LTC3642EDD-3.3#TRPBF LDYM 8-Lead (3mm 3mm) Plastic DFN 40C to 125C
LTC3642EDD-5#PBF LTC3642EDD-5#TRPBF 8-Lead (3mm 3mm) Plastic DFN 40C to 125C
LDYP
LTC3642IDD#PBF LTC3642IDD#TRPBF 40C to 125C
LDTJ 8-Lead (3mm 3mm) Plastic DFN
LTC3642IDD-3.3#PBF LTC3642IDD-3.3#TRPBF 8-Lead (3mm 3mm) Plastic DFN 40C to 125C
LDYM
LTC3642IDD-5#PBF LTC3642IDD-5#TRPBF 40C to 125C
LDYP 8-Lead (3mm 3mm) Plastic DFN
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: