LTC3646-1 Datasheet, PDF (1/28 Pages) Linear Technology – 40V, 1A Synchronous Step-Down Converter 1A Guaranteed Output Current

Features
n _{Wide Input Voltage Range: 4.0V to 40V}
n _{1A Guaranteed Output Current}
n _{High Efficiency: Up to 95%}
n _{Wide Output Voltage Range}
LTC3646: 2.0V to 30V
LTC3646-1: 0.6V to 15V
n _{±1% Accurate Reference Voltage}
n _{Internal or External Compensation}
n _{Switching Frequency Adjustable and Synchronizable:}
200kHz to 3MHz
n _{Selectable High Efficiency Burst Mode}^® _{Operation or}
Forced Continuous Mode
n _{14 Lead 3mm × 4mm DFN or Thermally Enhanced}
16-Lead MSOP Packages
Applications
n _{Point of Load Power Supply}
n _{Intermediate Bus Power}
n _{Automotive Applications}
LTC3646/LTC3646-1
40V, 1A Synchronous
Step-Down Converter
Description
The LTC^®3646 is a high efficiency, step-down DC/DC
converter with internal high side and synchronous power
FETs. It draws only 140µA typical DC supply current in
Burst Mode operation at no load while maintaining output
voltage regulation.
The LTC3646 can supply up to a 1A load, and its combina-
tion of Burst Mode operation, integrated power switches
and low quiescent current provides high efficiency over a
broad range of load currents. Alternatively, it can be used
in forced continuous mode for ripple sensitive applications.
The LTC3646 has a wide 4.0V to 40V input range and its
patented controlled on-time architecture and 0.6V reference
voltage allow for large step-down ratios without the risk of
overvoltage. The frequency may be set between 200kHz
to 3.0MHz with a program resistor or synchronized to an
external clock.
The internal soft-start, short-circuit protection and volt-
age rating make the LTC3646 a robust part ideal for high
voltage applications.
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
and Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents, including 6580258, 5481178,
5994885, 6304066, 5847554, 6476589, 6774611.
Typical Application
V_IN
40V MAX
10µF
4.7µF
PVIN
BOOST
SVIN
RUN
LTC3646
INTV_CC
SW
MODE/SYNC
ITH
RT
SWITCH ^VON
EXTV_CC ^CONTROL
+–
0.6V
V_FB
SGND
PGND
0.1µF
3.3µH
V_OUT
5V
1A
412k
15µF
56.2k
3646 TA01a
Efficiency Curve
100 _{VIN = 12V}
90 f = 1MHz
80
V_OUT = 5V
1.0
V_OUT = 3.3V _0.8
70
60
0.6
50
40
0.4
30
V_OUT = 5V
20
V_OUT = 3.3V
0.2
10
0
0
0.001
0.01
0.1
1
LOAD CURRENT (A)
3646 TA01b
36461f
1