LT3840
Wide Input Range
Synchronous Regulator Controller
with Accurate Current Limit
DescripTion
FeaTures
The LT®3840 is a high voltage synchronous step-down
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Wide Input Range: 2.5V to 60V
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switching regulator controller capable of operating from
a 2.5V to 60V supply.
Integrated Buck-Boost Supply for 7.5V MOSFET
Gate Drive
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Programmable Constant-Current Operation with
The LT3840’s low quiescent current, when configured for
user selectable Burst Mode operation, helps extend run
time in battery-powered systems by increasing efficiency
at light loads. The LT3840 uses a constant frequency,
current mode architecture. High current applications are
possible with large N-channel gate drivers capable of
Current Monitor Output
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Low I : 75µA, 12V to 3.3V
Q
IN
OUT
Selectable Low Output Ripple Burst Mode®
Operation
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V
Up to 60V
OUT
Adjustable and Synchronizable: 50kHz to 1MHz
Internal OVLO Protects for Input Transients Up to 80V
Accurate Input Overvoltage and Undervoltage Threshold
Programmable Soft-Start with Voltage Tracking
Power Good and Output OVP
driving multiple low R
MOSFETs.
DS(ON)
An integrated buck-boost switching regulator generates
a 7.5V bias supply voltage for MOSFET gate drive and IC
power allowing higher efficiency operation over the entire
inputvoltagerangeandeliminatingtheneedforanexternal
bias voltage. An accurate current limit set point regulates
the maximum output current. A current monitor reports
the average output current.
28-Lead TSSOP and 38-Lead 4mm × 6mm QFN Packages
applicaTions
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Automotive Supplies
L, LT, LTC, LTM, Linear Technology, Burst Mode, and the Linear logo are registered
trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
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Industrial Systems
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Distributed DC Power Systems
Typical applicaTion
High Efficiency Synchronous Step-Down Converter
12VIN to 3.3VOUT Efficiency
V
IN
4V TO 60V
1µF
68µF
×2
33µH
100
95
90
85
80
75
70
65
AUXBST AUXSW1 AUXSW2
EN
INTV
CC
4.7µF
1µF
V
IN
AUXVIN
UVLO
OVLO
PG
BOOST
LT3840
TG
SW
BG
1.5µH
2m
V
3.3V
20A
60
55
50
OUT
SYNC
MODE
RT
330µF
×2
0
5
10
15
20
LOAD CURRENT (A)
3840 TA01b
+
SENSE
–
V
SENSE
C
16.9k
10k
49.9k
20k
TK/SS
FB
1500pF
100pF
GND
IMON
2200pF
ICOMP
ICTRL
7.68k
470pF
3840 TA01a
3840fa
For more information www.linear.com/LT3840
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Linear [ Linear ]
