Switching Regulator. LT3681 Datasheet

LT3681 Regulator. Datasheet pdf. Equivalent

Part LT3681
Description Step-Down Switching Regulator
Feature www.DataSheet4U.com LT3681 36V, 2A, 2.8MHz Step-Down Switching Regulator with Integrated Power Scho.
Manufacture Linear Technology
Datasheet
Download LT3681 Datasheet



LT3681
www.DataSheet4U.com
LT3681
36V, 2A, 2.8MHz Step-Down
Switching Regulator with
Integrated Power Schottky Diode
FEATURES
Wide Input Voltage Range: 3.6V to 34V Operating,
36V Maximum
2A Maximum Output Current
Low Ripple Burst Mode® Operation
50µA IQ at 12VIN to 3.3VOUT
Output Ripple < 15mVP-P
Adjustable Switching Frequency: 300kHz to 2.8MHz
Low Shutdown Current: IQ < 1µA
Integrated Boost Diode
Integrated Power Schottky Diode
Power Good Flag
Saturating Switch Design: 0.18Ω On-Resistance
1.265V Feedback Reference Voltage
Output Voltage: 1.265V to 20V
Soft-Start Capability
Small 14-Pin Thermally Enhanced
(4mm x 3mm) DFN Package
U
APPLICATIO S
Automotive Battery Regulation
Power for Portable Products
Distributed Supply Regulation
Industrial Supplies
Wall Transformer Regulation
DESCRIPTIO
The LT®3681 is an adjustable frequency (300kHz to 2.8MHz)
monolithic buck switching regulator that accepts input
voltages up to 34V (36V maximum). A high efficiency
0.18Ω switch is included on the die along with a boost
Schottky diode and the necessary oscillator, control, and
logic circuitry. An undedicated power Schottky diode is
integrated into the LT3681 to minimize the solution size.
Current mode topology is used for fast transient response
and good loop stability. Low ripple Burst Mode operation
maintains high efficiency at low output currents while
keeping output ripple below 15mV in a typical application.
In addition, the LT3681 can further enhance low output
current efficiency by drawing bias current from the output
when VOUT is above 3V. Shutdown 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
90% of the programmed output voltage. The LT3681
is available in 14-Pin 4mm x 3mm DFN package 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 APPLICATIO
VIN
6.3V TO
34V
5V Step-Down Converter
OFF ON
VIN
RUN/SS
BD
BOOST
4.7mF
20k
330pF
60.4k
VC LT3681
RT
SW
DC
DA
PG BIAS
GND FB
0.47mF L
6.8mH
590k
200k
VOUT
5V
2A
22mF
L: NEC PLC-0745-6R8
3681 TA01
Efficiency
100
90
80
70
60
50
40
30
20
10
0
0.0001 0.001
10.0000
1.0000
0.1000
0.0100
0.01 0.1
ILOAD (A)
VIN = 12V
VOUT = 3.3V
L = 4.7mH
0.0010
F = 800 kHz
0.0001
1 10
3681 TA01b
3681f
1



LT3681
www.DataSheet4U.com
LT3681
ABSOLUTE AXI U RATI GS
(Note 1)
VIN, RUN/SS Voltage.................................................36V
BOOST Pin Voltage ...................................................56V
BOOST Pin Above SW Pin.........................................30V
FB, RT, VC Voltage.......................................................5V
BIAS, PG, BD Voltage................................................30V
Maximum Junction Temperature .......................... 125°C
DC above DA.............................................................40V
Operating Temperature Range (Note 2)
LT3681E............................................... –40°C to 85°C
Storage Temperature Range................... –65°C to 150°C
UW U
PACKAGE/ORDER I FOR ATIO
TOP VIEW
PG
BIAS
FB
GND
VC
RT
GND
1
2
3
4
5
6
7
14 RUN/SS
15 13 VIN
12 SW
11 BOOST
10 BD
16 9 DC
8 DA
DE14MA PACKAGE
14-LEAD (4mm ´ 3mm) PLASTIC DFN
TJMAX = 125°C, θJA = 43°C/W
EXPOSED PAD (PIN 15) IS GND, MUST BE SOLDERED TO PCB
EXPOSED PAD PIN 16 IS DC
ORDER PART NUMBER DE PART MARKING
LT3681EDE
3681
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 10V, VRUNS/SS = 10V, VBOOST = 15V, VBIAS = 3.3V unless otherwise
noted. (Note 2)
PARAMETER
Minimum Input Voltage
Quiescent Current from VIN
Quiescent Current from BIAS
Minimum Bias Voltage
Feedback Voltage
FB Pin Bias Current (Note 3)
FB Voltage Line Regulation
Error Amp GM
Error Amp Gain
VC Source Current
VC Sink Current
VC Pin to Switch Current Gain
VC Clamp Voltage
CONDITIONS
VRUN/SS = 0.2V
VBIAS = 3V, Not Switching
VBIAS = 0, Not Switching
VRUN/SS = 0.2V
VBIAS = 3V, Not Switching
VBIAS = 0, Not Switching
VFB = 1.25V, VC = 0.4V
4V < VIN < 34V
MIN
1.25
1.24
TYP
3
0.01
22
75
0.01
50
0
2.7
1.265
1.265
30
0.002
330
800
65
85
3.5
2
MAX
3.6
0.5
60
120
0.5
120
5
3
1.29
1.3
100
0.02
UNITS
V
μA
μA
μA
μA
μA
μA
V
V
V
nA
%/V
μMho
μA
μA
A/V
V
3681f
2







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