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 refer-
ence voltage allow for large step-down ratios without
the risk of output overvoltage. The frequency may be set
between 200kHz and 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.
n
n
n
n
n
Wide Input Voltage Range: 4.0V to 40V
1A Guaranteed Output Current
High Efficiency: Up to 95%
Wide Output Voltage Range
n
LTC3646: 2.0V to 30V
n
LTC3646-1: 0.6V to 15V
±1% Accurate Reference Voltage
Internal or External Compensation
Switching Frequency Adjustable and Synchronizable:
200kHz to 3MHz
Selectable High Efficiency Burst Mode
®
Operation or
Forced Continuous Mode
14 Lead 3mm × 4mm DFN or Thermally Enhanced
16-Lead MSOP Packages
APPLICATIONS
n
n
n
Point of Load Power Supplies
Intermediate Bus Power
Automotive Applications
TYPICAL APPLICATION
Efficiency Curve
V
IN
40V MAX
PVIN
SVIN
RUN
10µF
INTV
CC
MODE/SYNC
ITH
RT
EXTV
CC
4.7µF
0.6V
SGND
SWITCH
CONTROL
V
ON
412k
LTC3646
SW
BOOST
0.1µF
3.3µH
100
90
80
EFFICIENCY (%)
V
OUT
5V
1A
V
IN
= 12V
f = 1MHz
1.0
V
OUT
= 5V
V
OUT
= 3.3V
0.8
POWER LOSS (W)
70
60
50
40
30
V
OUT
= 5V
V
OUT
= 3.3V
0.2
0.4
0.6
+ –
PGND
V
FB
56.2k
3646 TA01a
15µF
20
10
0
0.001
0.01
0.1
LOAD CURRENT (A)
1
3646 TA01b
0
36461fc
For more information
www.linear.com/LTC3646
1
LTC3646/LTC3646-1
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 7)
PVIN, SVIN Supply Voltage ........................ –0.3V to 45V
SW Voltage (DC) ........................... –0.3V to PVIN + 0.3V
BOOST – SW Voltage ................................... –0.3V to 6V
V
ON
Voltage................................................ –0.3V to 33V
MODE/SYNC, RT, ITH,
V
FB
Voltage ................................–0.3V to INTV
CC
+ 0.3V
INTV
CC
Voltage ............................................ –0.3V to 6V
EXTV
CC
Voltage ........................................... –0.3V to 6V
RUN Voltage............................................... –0.3V to 45V
PGOOD.......................................–0.3V to INTV
CC
+ 0.3V
Operating Junction Temperature Range
(Notes 2, 7) ............................................ –40°C to 150°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec) MSE .......... 300°C
PIN CONFIGURATION
TOP VIEW
SGND
V
FB
ITH
RT
V
ON
PGOOD
MODE/SYNC
1
2
3
4
5
6
7
15
PGND
14 SVIN
13 RUN
12 EXTV
CC
11 INTV
CC
10 BOOST
9 SW
8 PVIN
TOP VIEW
SGND
V
FB
ITH
RT
V
ON
PGOOD
MODE/SYNC
NC
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
SVIN
RUN
EXTV
CC
INTV
CC
BOOST
SW
PVIN
PVIN
17
PGND
DE PACKAGE
14-LEAD (4mm
×
3mm) PLASTIC DFN
T
JMAX
= 150°C,
θ
JA
= 43°C/W
EXPOSED PAD (PIN 15) IS PGND, MUST BE SOLDERED TO PCB
MSE PACKAGE
16-LEAD PLASTIC MSOP
T
JMAX
= 150°C,
θ
JA
= 38°C/W
EXPOSED PAD (PIN 17) IS PGND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC3646EDE#PBF
LTC3646IDE#PBF
LTC3646HDE#PBF
LTC3646EMSE#PBF
LTC3646IMSE#PBF
LTC3646HMSE#PBF
LTC3646EDE-1#PBF
LTC3646IDE-1#PBF
LTC3646HDE-1#PBF
LTC3646EMSE-1#PBF
LTC3646IMSE-1#PBF
LTC3646HMSE-1#PBF
TAPE AND REEL
LTC3646EDE#TRPBF
LTC3646IDE#TRPBF
LTC3646HDE#TRPBF
LTC3646EMSE#TRPBF
LTC3646IMSE#TRPBF
LTC3646HMSE#TRPBF
LTC3646EDE-1#TRPBF
LTC3646IDE-1#TRPBF
LTC3646HDE-1#TRPBF
LTC3646EMSE-1#TRPBF
LTC3646IMSE-1#TRPBF
PART MARKING
3646
3646
3646
3646
3646
3646
36461
36461
36461
36461
36461
PACKAGE DESCRIPTION
14-Lead (4mm
×
3mm) Plastic DFN
14-Lead (4mm
×
3mm) Plastic DFN
14-Lead (4mm
×
3mm) Plastic DFN
16-Lead Plastic MSOP
16-Lead Plastic MSOP
16-Lead Plastic MSOP
14-Lead (4mm
×
3mm) Plastic DFN
14-Lead (4mm
×
3mm) Plastic DFN
14-Lead (4mm
×
3mm) Plastic DFN
16-Lead Plastic MSOP
16-Lead Plastic MSOP
16-Lead Plastic MSOP
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 125°C
–40°C to 150°C
–40°C to 85°C
–40°C to 125°C
–40°C to 150°C
–40°C to 85°C
–40°C to 125°C
–40°C to 150°C
–40°C to 85°C
–40°C to 125°C
–40°C to 150°C
LTC3646HMSE-1#TRPBF 36461
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
2
36461fc
For more information
www.linear.com/LTC3646
LTC3646/LTC3646-1
ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
Input Supply (PVIN, SVIN)
Input Voltage Operating Range
V
IN
Input Supply Overvoltage Lockout
V
IN(OV)
V
IN(UV)
I
Q
Input Supply Undervoltage Lockout
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
1 Introduction
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