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| LT3844EFE Datasheet, PDF (1/24 Pages) Linear Technology – High Voltage, Current Mode Switching Regulator Controller with Programmable Operating Frequency | |||
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LT3844
High Voltage, Current Mode
Switching Regulator Controller with
Programmable Operating Frequency
FEATURES
n High Voltage Operation: Up to 60V
n Output Voltages Up to 36V (Step Down)
n Programmable Constant Frequency: 100kHz to
500kHz
n Synchronizable up to 600kHz
n Burst Mode® Operation: 120μA Supply Current
n 10μA Shutdown Supply Current
n ±1.3% Reference Accuracy
n Drives N-Channel MOSFET
n Programmable Soft-Start
n Programmable Undervoltage Lockout
n Internal High Voltage Regulator for Gate Drive
n Thermal Shutdown
n Current Limit Unaffected by Duty Cycle
n 16-Pin Thermally Enhanced TSSOP Package
APPLICATIONS
n Industrial Power Distribution
n 12V and 42V Automotive and Heavy Equipment
n High Voltage Single Board Systems
n Distributed Power Systems
n Avionics
n Telecom Power
DESCRIPTION
The LT®3844 is a DC/DC controller used for medium power,
low part count, high efï¬ciency supplies. It offers a wide
4V to 60V input range (7.5V minimum start-up voltage)
and can implement step-down, step-up, inverting and
SEPIC topologies.
The LT3844 includes Burst Mode operation, which reduces
quiescent current below 120μA and maintains high efï¬-
ciency at light loads. An internal high voltage bias regulator
allows for simple biasing.
Additional features include current mode control for fast
line and load transient response; programmable ï¬xed
operating frequency that can be synchronized to an ex-
ternal clock for noise sensitive applications; a gate driver
capable of driving large N-channel MOSFETs; a precision
undervoltage lockout function; 10μA shutdown current;
short-circuit protection and a programmable soft-start
function.
The LT3844 is available in a 16-lead thermally enhanced
TSSOP package.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 5731694, 6498466, 6611131
TYPICAL APPLICATION
High Voltage Step-Down Regulator 48V to 12V, 50W
VIN
36V TO 60V
68μF
14.7k
130k
22μF
1M
VIN
82.5k
SHDN
1000pF
CSS
BOOST
TG
10Ω
SW
10k
680p
BURST_EN
VCC
LT3844
1μF
VFB
PGND
VC
120pF
SYNC
SENSE+
SENSEâ
fSET
R7
49.9k
SGND
0.22μF
Si7850DP
10μH 0.015Ω
PDS5100H
68μF
VOUT
12V
50W
33μF
3844 TA01
Efï¬ciency and Power Loss
vs Load Current
90 VIN = 48V
7
88
6
86
EFFICIENCY
5
84
4
82
3
LOSS
80
2
78
1
76
0.1
1
LOAD CURRENT (A)
0
10
3844 TA01b
3844fb
1
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