Switching Regulator. LT3685 Datasheet

LT3685 Regulator. Datasheet pdf. Equivalent

Part LT3685
Description Step-Down Switching Regulator
Feature www.DataSheet4U.com LT3685 38V, 2A, 2.4MHz Step-Down Switching Regulator FEATURES ■ DESCRIPTION Th.
Manufacture Linear Technology
Datasheet
Download LT3685 Datasheet




LT3685
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LT3685
38V, 2A, 2.4MHz Step-Down
Switching Regulator
FEATURES
Wide Input Range:
Operation From 3.6V to 38V
Overvoltage Lockout Protects Circuit through
60V Transients
2A Maximum Output Current
Adjustable Switching Frequency: 200kHz to 2.4MHz
Low Shutdown Current: IQ < 1μA
Integrated Boost Diode
Synchronizable Between 250kHz to 2MHz
Power Good Flag
Saturating Switch Design: 0.25 On-Resistance
0.790V Feedback Reference Voltage
Output Voltage: 0.79V to 20V
Soft-Start Capability
Small 10-Pin Thermally Enhanced MSOP and
(3mm × 3mm) DFN Packages
APPLICATIONS
Automotive Battery Regulation
Set Top Box
Distributed Supply Regulation
Industrial Supplies
Wall Transformer Regulation
DESCRIPTION
The LT®3685 is an adjustable frequency (200kHz to 2.4MHz)
monolithic step-down switching regulator that accepts
input voltages up to 38V operating and 60V maximum.
An internal overvoltage protection circuit turns off the
power switch when VIN is above 41.5V typical (38V mini-
mum) which then allows the part to safely withstand 60V
transients. A high efficiency 0.25 switch is included on
the die along with a boost Schottky diode and the neces-
sary oscillator, control, and logic circuitry. Current mode
topology is used for fast transient response and good
loop stability. The LT3685’s high operating frequency
allows the use of small, low cost inductors and ceramic
capacitors resulting in low output ripple while keeping total
solution size to a minimum. The low current shutdown
mode reduces input supply current to less than 1μA while
a resistor and capacitor on the RUN/SS pin provide a
controlled output voltage ramp (soft-start). A power good
flag signals when VOUT reaches 86% of the programmed
output voltage. The LT3685 is available in 10-Pin MSOP
and 3mm × 3mm DFN packages with exposed pads for
low thermal resistance.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
TYPICAL APPLICATION
VIN
4.5V TO 38V
TRANSIENT
TO 60V
3.3V Step-Down Converter
OFF ON
VIN
RUN/SS
BD
BOOST
4.7μF
470pF
14k
40.2k
VC LT3685
RT
PG
SYNC
GND
SW
FB
0.47μF 4.7μH
316k
100k
VOUT
3.3V
2A
22μF
3685 TA01
100
90
80
70
60
50
0
Efficiency
VOUT = 5V
VOUT = 3.3V
VIN = 12V
L = 5.6μH
F = 800 kHz
0.5 1.0 1.5
LOAD CURRENT (A)
2
3685 TA01b
3685f
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LT3685
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LT3685
ABSOLUTE MAXIMUM RATINGS
(Note 1)
VIN, RUN/SS Voltage (Note 5)...................................60V
BOOST Pin Voltage ...................................................56V
BOOST Pin Above SW Pin.........................................30V
FB, RT, VC Voltage.......................................................5V
PG, BD, SYNC Voltage ..............................................30V
Operating Junction Temperature Range (Note 2)
LT3685E............................................. –40°C to 125°C
LT3685I ............................................. –40°C to 125°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
(MSE Only) ....................................................... 300°C
PIN CONFIGURATION
TOP VIEW
BD
BOOST
SW
VIN
RUN/SS
1
2
3
4
5
10 RT
9 VC
11 8 FB
7 PG
6 SYNC
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
JA = 45°C/W, JC = 10°C/W
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
BD 1
BOOST 2
SW 3
VIN 4
RUN/SS 5
TOP VIEW
11
10 RT
9 VC
8 FB
7 PG
6 SYNC
MSE PACKAGE
10-LEAD PLASTIC MSOP
JA = 45°C/W, JC = 10°C/W
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
LT3685EDD#PBF
LT3685IDD#PBF
LT3685EMSE#PBF
LT3685IMSE#PBF
LT3685EDD#TRPBF
LT3685IDD#TRPBF
LT3685EMSE#TRPBF
LT3685IMSE#TRPBF
LCYG
LCYG
LTCYF
LTCYF
10-Lead (3mm × 3mm) Plastic DFN
10-Lead (3mm × 3mm) Plastic DFN
10-Lead Plastic MSOP
10-Lead Plastic MSOP
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
*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/
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 10V, VRUN/SS = 10V, VBOOST = 15V, VBD = 3.3V unless otherwise
noted. (Note 2)
PARAMETER
Minimum Input Voltage
VIN Overvoltage Lockout
Quiescent Current from VIN
CONDITIONS
VRUN/SS = 0.2V
VBD = 3V, Not Switching
VBD = 0, Not Switching
MIN
38
TYP MAX UNITS
3 3.6
V
41.5 45
V
0.01 0.5
450 600
1.3 1.7
μA
μA
μA
3685f
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