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LT3645IMSE#TRPBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24
LT3645
1
3645f
LOAD CURRENT (mA)
0 100
50
EFFICIENCY (%)
60
70
80
90
200
300
3645 TA01b
400 500
V
OUT
= 3.3V
V
IN
= 12V
V
OUT
= 5V
TYPICAL APPLICATION
FEATURES DESCRIPTION
36V 500mA Step-Down
Regulator and 200mA LDO
The LT
®
3645 is a dual output regulator combining a 500mA
buck regulator and a 200mA low dropout linear regula-
tor (LDO). The wide input voltage range of 3.6V to 36V
makes the LT3645 suitable for regulating power from a
wide variety of sources, including 24V industrial supplies
and automotive batteries. Its high operating frequency
allows the use of tiny, low cost inductors and capacitors,
resulting in a very small solution.
Cycle-by-cycle current limit and frequency foldback pro-
vide protection against shorted outputs. Soft-start and
frequency foldback eliminate input current surge during
start-up.
The linear regulator operates from the V
CC2
pin at voltages
down to 1.2V. It supplies 200mA of output current with a
typical dropout voltage of 310mV.
Other features of the LT3645 include a <2µA shutdown,
short circuit protection, soft-start and thermal shutdown.
The LT3645 is available in the thermally enhanced 16-lead
(3mm × 3mm) QFN package, or a 12-lead MSE package.
3.3V/5V Step-Down Converter
APPLICATIONS
n
Automotive CMOS Image Sensors
n
Industrial/Automotive Micro-Controller Supply
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.
n
Wide Input Range:
Operation from 3.6V to 36V
Overvoltage Lockout Protects Circuit Through
55V Transients on Input
n
500mA Output Current Switching Regulator
n
High Switching Frequency: 750kHz
n
200mA Low Dropout Linear Regulator
1.2V to 16V Input; 0.8V to 8V Output
310mV Dropout Voltage V
CC2
to OUT2
n
Precision Programmable Undervoltage Lockout
n
Short-Circuit Robust
n
Internal Soft-Start
n
<2µA Shutdown Current
n
Small Thermally Enhanced 16-Lead (3mm × 3mm)
QFN and 12-Lead MSE Packages
Buck Regulator Effi ciency
1µF
3645 TA01a
PGOOD
6.2V TO 36V
GND
SW
DA
FB
FB2
EN2
V
CC2
V
IN
EN/UVLO
NPG
OUT2
10µF
5V
300mA
3.3V
200mA
15µH
52.3k
31.6k
10k
10k
BOOST
LT3645
2.2µF
0.1µF
ON OFF
LT3645
2
3645f
PIN CONFIGURATION
ABSOLUTE MAXIMUM RATINGS
V
IN
, EN/UVLO (Note 5) .......................…….–0.3V to 55V
BOOST Voltage……………………………………….55V
BOOST Above SW Voltage ...............................…….25V
V
CC2
Voltage .............................................. –0.3V to 16V
V
OUT2
Voltage .............................................. –0.3V to 8V
FB, FB2 Voltages .......................................... –0.3V to 6V
(Note 1)
16 15 14 13
5 6 7 8
TOP VIEW
UD PACKAGE
16-LEAD (3mm × 3mm) PLASTIC QFN
9
10
11
12
4
3
2
1NC
NC
NPG
EN2
NC
V
IN
BOOST
SW
FB2
OUT2
V
CC2
NC
EN/UVLO
FB
GND
DA
17
GND
θ
JA
= 58.7°C/W, θ
JC
= 7.1°C/W
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
1
2
3
4
5
6
EN/UVLO
FB
GND
DA
BOOST
SW
12
11
10
9
8
7
NPG
EN2
FB2
OUT2
V
CC2
V
IN
TOP VIEW
MSE PACKAGE
12-LEAD PLASTIC MSOP
13
GND
θ
JA
= 40°C/W, θ
JC
= 5°C/W TO 10°C/W
EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT3645EUD#PBF LT3645EUD#TRPBF LFVS 16-Lead Plastic QFN –40°C to 125°C
LT3645IUD#PBF LT3645IUD#TRPBF LFVS 16-Lead Plastic QFN –40°C to 125°C
LT3645EMSE#PBF LT3645EMSE#TRPBF 3645 12-Lead Plastic MSOP –40°C to 125°C
LT3645IMSE#PBF LT3645IMSE#TRPBF 3645 12-Lead Plastic MSOP –40°C to 125°C
LT3645HMSE#PBF LT3645HMSE#TRPBF 3645 12-Lead Plastic MSOP –40°C to 150°C
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based fi nish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifi cations, go to: http://www.linear.com/tapeandreel/
EN2, NPG Voltages .................................... –0.3V to 16V
Operating Junction Temperature Range (Note 2)
LT3645E ............................................ –40°C to 125°C
LT3645I ............................................. –40°C to 125°C
LT3645H ............................................ –40°C to 150°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)…… ...........300°C
LT3645
3
3645f
ELECTRICAL CHARACTERISTICS
PARAMETER CONDITIONS MIN TYP MAX UNITS
Undervoltage Lockout on V
IN
Rising
l
3 3.4 3.6 V
Overvoltage Lockout on V
IN
Rising
l
36 38.5 40 V
Overvoltage Lockout Hysteresis 1V
Feedback Voltage FB
l
0.79
0.785
0.8
0.8
0.81
0.813
V
FB Pin Bias Current
l
20 300 nA
Feedback Voltage Line Regulation
l
0.015 %/V
V
IN
Quiescent Current Not Switching 1.4 3 mA
V
IN
Quiescent Current in Shutdown V
EN/UVLO
= 0.3V, V
CC2
= 0V, V
OUT2
= 0V 0.01 2 µA
Switching Frequency 675 750 825 kHz
Maximum Duty Cycle 100mA Load
l
83 87 %
Switch Current Limit Rising (Note 4) 0.8 1 1.25 A
DA Pin Current to Stop Osc 0.6 1 1.25 A
Switch V
CESAT
I
SW
= 500mA 400 mV
Switch Leakage Current 2µA
Minimum Boost Voltage Above Switch I
SW
= 500mA 1.6 2.2 V
BOOST Pin Current I
SW
= 500mA 10 18 mA
BOOST Schottky Forward Drop I
OUT
= 50mA 0.7 0.9 V
EN/UVLO Threshold High Rising 1.17 1.23 1.29 V
EN/UVLO Threshold Hysteresis 50 mV
EN/UVLO Input Current V
EN/UVLO
= 5V
V
EN/UVLO
= 0V
25 50
1
µA
µA
Buck Soft-Start Time 0.9 1.8 ms
LDO Minimum Input Voltage V
CC2
I
LOAD
= 200mA, V
OUT2
= 0.8V, V
IN
= 4.0V 1.1 1.38 V
LDO Feedback Voltage FB2
l
782 797 810 mV
LDO FB2 Bias Current
l
20 300 nA
LDO Line Regulation 0.020 %/V
LDO Load Regulation –1 mV
LDO Dropout Voltage (V
CC2
to V
OUT2
)I
LOAD
= 10mA
I
LOAD
= 10mA
I
LOAD
= 200mA
l
45
310
65
145
mV
mV
mV
LDO Dropout Voltage (V
IN
to V
OUT2
)I
LOAD
= 200mA
I
LOAD
= 200mA
l
1.1 1.4
1.7
V
V
LDO Current Limit
l
210
270 mA
mA
EN2 Pin Threshold Rising
Falling
l
l
0.5
1.3
0.8
1.6 V
V
LDO Soft-Start Time 0.6 1.2 ms
NPG V
CESAT
I
NPG
= 1mA, V
FB
= V
FB2
= 850mV 0.4 V
NPG Leakage V
NPG
= 16V, V
FB
= V
FB2
= 750mV 0.5 µA
FB2 NPG Threshold, % of Regulation Voltage V
FB
= 800mV, V
FB2
Rising 88 90 92 %
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. V
IN
= 12V, BOOST = 15.3V, V
CC2
= 3.3V, OUT2 = 1.8V unless
otherwise noted. (Notes 2, 3)
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LT3645IMSE#TRPBF

Mfr. #:
Buy LT3645IMSE#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators 36Vin (55V Trans) 500mA Buck plus 200mA LDO
Lifecycle:
New from this manufacturer.
Delivery:
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