LT3840_15 Datasheet, PDF (1/24 Pages) Linear Technology – Wide Input Range Synchronous Regulator Controller with Accurate Current Limit

LT3840
Features
Wide Input Range
Synchronous Regulator Controller
with Accurate Current Limit
Description
n _{Wide Input Range: 2.5V to 60V}
n _{Integrated Buck-Boost Supply for 7.5V MOSFET}
Gate Drive
n _{Programmable Constant-Current Operation with}
Current Monitor Output
n _{Low IQ: 75µA, 12VIN to 3.3VOUT}
n _{Selectable Low Output Ripple Burst Mode}^®
Operation
n _{VOUT Up to 60V}
n _{Adjustable and Synchronizable: 50kHz to 1MHz}
n _{Internal OVLO Protects for Input Transients Up to 80V}
n _{Accurate Input Overvoltage and Undervoltage Threshold}
n _{Programmable Soft-Start with Voltage Tracking}
n _{Power Good and Output OVP}
n _{28-Lead TSSOP and 38-Lead 4mm × 6mm QFN Packages}
Applications
n _{Automotive Supplies}
n _{Industrial Systems}
n _{Distributed DC Power Systems}
The LT^®3840 is a high voltage synchronous step-down
switching regulator controller capable of operating from
a 2.5V to 60V supply.
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
driving multiple low R_DS(ON) MOSFETs.
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
input voltage range and eliminating the need for an external
bias voltage. An accurate current limit set point regulates
the maximum output current. A current monitor reports
the average output current.
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.
Typical Application
V_IN
4V TO 60V
High Efficiency Synchronous Step-Down Converter
68µF
1µF
33µH
×2
49.9k
AUXBST AUXSW1
EN
V_IN
AUXVIN
UVLO
LT3840
AUXSW2
INTV_CC
BOOST
OVLO
TG
PG
SW
SYNC
BG
20k
1500pF
MODE
RT
SENSE⁺
V_C
SENSE^–
TK/SS
FB
100pF
IMON
ICOMP
GND
ICTRL
2200pF
7.68k
470pF
4.7µF
1µF
1.5µH
2m
16.9k
10k
V_OUT
3.3V
20A
330µF
×2
3840 TA01a
12V_IN to 3.3V_OUT Efficiency
100
95
90
85
80
75
70
65
60
55
50
0
5
10
15
LOAD CURRENT (A)
20
3840 TA01b
For more information www.linear.com/LT3840
3840fa
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