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LT3574IMS#TRPBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24
LT3574
1
3574f
Features
applications
Description
Isolated Flyback Converter
Without an Opto-Coupler
The LT
®
3574 is a monolithic switching regulator specifi-
cally designed for the isolated flyback topology. No third
winding or opto-isolator is required for regulation. The
part senses the isolated output voltage directly from the
primary side flyback waveform. A 0.65A, 60V NPN power
switch is integrated along with all control logic into a
16
-
lead MSOP package.
The LT3574 operates with input supply voltages from
3V to 40V, and can deliver output power up to 3W with
no external power switch. The LT3574 utilizes boundary
mode operation to provide a small magnetic solution with
improved load regulation.
The output voltage is easily set with two external resistors
and the transformer turns ratio. Off-the-shelf transformers
are available for many applications.
5V Isolated Flyback Converter
n
3V to 40V Input Voltage Range
n
0.65A, 60V Integrated NPN Power Switch
n
Boundary Mode Operation
n
No Transformer Third Winding or
Opto-Isolator Required for Regulation
n
Improved Primary-Side Winding Feedback
Load Regulation
n
V
OUT
Set with Two External Resistors
n
BIAS Pin for Internal Bias Supply and Power
NPN Driver
n
Programmable Soft-Start
n
Programmable Power Switch Current Limit
n
16-Lead MSOP Package
n
Industrial, Automotive and Medical Isolated
Power Supplies
Load Regulation
SHDN/UVLO
TC
R
ILIM
SS
R
FB
R
REF
SW
VC GND TEST BIAS
LT3574
3574 TA01
28.7k
10k
59k
V
IN
12V TO 24V
V
OUT
+
5V
0.35A
V
OUT
–
V
IN
3:1
357k
51.1k
10
µF
5.6
µH50µH
•
•
22µF
10nF
1nF
4.7µF
6.04k
2k
80.6k
B340A
PMEG6010
0.22µF
I
OUT
(mA)
0
–1.0
OUTPUT VOLTAGE ERROR (%)
–0.5
0
0.5
1.0
100 200 300 400
3574 TA01b
500 600 700
V
IN
= 24V
V
IN
= 12V
typical application
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
and No R
SENSE
and ThinSOT are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
LT3574
2
3574f
absolute MaxiMuM ratings
SW ............................................................................60V
V
IN
, SHDN/UVLO, R
FB
, BIAS .....................................40V
SS, VC, T
C
, R
REF
, R
ILIM
...............................................5V
Maximum Junction Temperature .......................... 125°C
Operating Junction Temperature Range
(Note 2) ..................................................–40°C to 125°C
Storage Temperature Range ..................–65°C to 150°C
orDer inForMation
electrical characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, unless otherwise noted.
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT3574EMS#PBF LT3574EMS#TRPBF 3574 16-Lead Plastic MSOP –40°C to 125°C
LT3574IMS#PBF LT3574IMS#TRPBF 3574 16-Lead Plastic MSOP –40°C to 125°C
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/
PARAMETER CONDITIONS MIN TYP MAX UNITS
Input Voltage Range
l
3 40 V
Quiescent Current SS = 0V
V
SHDN/UVLO
= 0V
3.5
0
1
mA
µA
Soft-Start Current SS = 0.4V 7 µA
SHDN/UVLO Pin Threshold UVLO Pin Voltage Rising
l
1.15 1.22 1.29 V
SHDN/UVLO Pin Hysteresis Current V
UVLO
= 1V 2 2.5 3 µA
Soft-Start Threshold 0.7 V
Maximum Switching Frequency 1000 kHz
Switch Current Limit R
ILIM
= 10k 0.65 0.9 1.1 A
Minimum Current Limit V
C
= 0V 100 mA
Switch V
CESAT
I
SW
= 0.5A 150 250 mV
R
REF
Voltage V
IN
= 3V
l
1.21
1.20
1.23 1.25
1.25
V
R
REF
Voltage Line Regulation 3V < V
IN
< 40V 0.01 0.03 %/ V
R
REF
Pin Bias Current (Note 3)
l
100 600 nA
I
REF
Reference Current Measured at R
FB
Pin with R
REF
= 6.49k 190 µA
Error Amplifier Voltage Gain V
IN
= 3V 150 V/V
pin conFiguration
1
2
3
4
5
6
7
8
GND
TEST
GND
SW
V
IN
BIAS
SHDN/UVLO
GND
16
15
14
13
12
11
10
9
GND
TC
R
REF
R
FB
VC
R
ILIM
SS
GND
TOP VIEW
MS PACKAGE
16-LEAD PLASTIC MSOP
T
JMAX
= 125°C, θ
JA
= 120°C/W, θ
JC
= 21°C/W
LT3574
3
3574f
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LT3574E is guaranteed to meet performance specifications
from 0°C to 125°C junction temperature. Specifications over the –40°C
to 125°C operating junction temperature range are assured by design
characterization and correlation with statistical process controls. The
LT3574I is guaranteed over the full –40°C to 125°C operating junction
temperature range.
Note 3: Current flows out of the R
REF
pin.
electrical characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, unless otherwise noted.
typical perForMance characteristics
Output Voltage Quiescent Current
Bias Pin Voltage
T
A
= 25°C, unless otherwise noted.
TEMPERATURE (°C)
–50
4.80
V
OUT
(V)
4.85
4.95
5.00
5.05
5.20
5.15
0
50
75
4.90
5.10
–25
25
100
125
3574 G01
TEMPERATURE (°C)
–50
QUIESCENT CURRENT (mA)
4
5
6
25 75
3574 G02
3
2
–25 0
50 100 125
1
0
V
IN
= 40V
BIAS = 20V
V
IN
= 5V
BIAS = 5V
TEMPERATURE (°C)
–50
2.0
BIAS VOLTAGE (V)
2.4
2.6
2.8
3.2
0
50
75
2.2
3.0
–25
25
100
125
3574 G03
V
IN
= 40V
V
IN
= 12V
PARAMETER CONDITIONS MIN TYP MAX UNITS
Error Amplifier Transconductance
DI = 10µA, V
IN
= 3V
150 µmhos
Minimum Switching Frequency V
C
= 0.35V 40 kHz
TC Current into R
REF
R
TC
= 20.1k 27.5 µA
BIAS Pin Voltage I
BIAS
= 30mA 2.9 3 3.1 V
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LT3574IMS#TRPBF

Mfr. #:
Buy LT3574IMS#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators Iso Fly Conv Without an Opto-Coupler
Lifecycle:
New from this manufacturer.
Delivery:
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