LT3724
High Voltage, Current Mode
Switching Regulator Controller
FEATURES
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DESCRIPTION
The LT
®
3724 is a DC/DC controller used for medium power,
low part count, low cost, high efficiency supplies. It of-
fers a wide 4V-60V input range (7.5V minimum startup
voltage) and can implement step-down, step-up, inverting
and SEPIC topologies.
The LT3724 includes Burst Mode operation, which re-
duces quiescent current below 100µA and maintains
high efficiency at light loads. An internal high voltage bias
regulator allows for simple biasing and can be back driven
to increase efficiency.
Additional features include fixed frequency current mode
control for fast line and load transient response; 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 that directly controls output voltage slew rates at
startup which limits inrush current, minimizes overshoot
and facilitates supply sequencing.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
Burst Mode is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners. Protected by U.S. Patents including 5731694, 6498466, 6611131.
Wide Input Range: 4V to 60V
Output Voltages up to 36V (Step-Down)
Burst Mode
®
Operation: <100µA Supply Current
10µA Shutdown Supply Current
±1.3% Reference Accuracy
200kHz Fixed Frequency
Drives N-Channel MOSFET
Programmable Soft-Start
Programmable Undervoltage Lockout
Internal High Voltage Regulator for Gate Drive
Thermal Shutdown
Current Limit Unaffected by Duty Cycle
16-Pin Thermally Enhanced TSSOP Package
APPLICATIONS
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Industrial Power Distribution
12V and 42V Automotive and Heavy Equipment
High Voltage Single Board Systems
Distributed Power Systems
Avionics
Telecom Power
TYPICAL APPLICATION
High Voltage Step-Down Regulator
V
IN
30V TO
60V
C
IN
68µF
1M
95
Efficiency and Power Loss
vs Load Current
12
10
EFFICIENCY
EFFICIENCY (%)
8
6
4
LOSS
V
IN
= 48V
65
0.1
1
LOAD CURRENT (A)
0
10
3724 TA01b
V
IN
BOOST
LT3724
TG
SW
0.22µF
10Ω
47µH
SS3H9
V
CC
PGND
SENSE
+
SENSE
–
3724 TA01a
90
Si7852
0.025Ω
V
OUT
24V
75W
C
OUT
330µF
85
80
75
70
POWER LOSS (W)
SHDN
68.1k
200k
C
SS
Burst_EN
V
FB
40.2k
680pF
120pF
4.99k
93.1k
1000pF
V
C
SGND
+
1µF
2
3724fd
1
LINER [ LINEAR TECHNOLOGY ]
