DC/DC Controller. LTC3854 Datasheet

LTC3854 Controller. Datasheet pdf. Equivalent

Part LTC3854
Description Wide Vin Range Synchronous Step-Down DC/DC Controller
Feature www.DataSheet4U.com FEATURES n n n n n n n n n n n n n n LTC3854 Small Footprint, Wide VIN Range S.
Manufacture Linear Technology Corporation
Datasheet
Download LTC3854 Datasheet



LTC3854
LTC3854
Small Footprint, Wide
VIN Range Synchronous
Step-Down DC/DC Controller
FEATURES
DESCRIPTION
n Wide Operating VIN Range: 4.5V to 38V
n RSENSE or DCR Current Sensing
n ±1% 0.8V Reference Accuracy Over Temperature
n 400kHz Switching Frequency
n Dual N-channel MOSFET Synchronous Drive
n Very Low Dropout Operation: 97% Duty Cycle
n Starts Up Into Pre-Biased Output
n Adjustable Output Voltage Soft-Start
n Output Current Foldback Limiting
(Disabled During Soft-Start)
n Output Overvoltage Protection
n 5V LDO for External Gate Drive
n OPTI-LOOP® Compensation Minimizes COUT
n Low Shutdown IQ: 15µA
n Tiny Thermally Enhanced 12-Pin 2mm × 3mm DFN
and MSOP Packages
APPLICATIONS
n Automotive Systems
n Telecom Systems
n Industrial Equipment
n Distributed DC Power Systems
The LTC3854® is a high performance synchronous step-
down switching DC/DC controller that drives an all N-
channel synchronous power MOSFET stage.
The LTC3854 features a 400kHz constant frequency current
mode architecture. The LTC3854 operates from a 4.5V to
38V (40V absolute maximum) input voltage range and
regulates the output voltage from 0.8V to 5.5V.
The RUN/SS pin provides both soft-start and enable
features. OPTI-LOOP compensation allows the transient
response to be optimized over a wide range of output ca-
pacitance and ESR values. Current foldback limits MOSFET
dissipation during short circuit conditions. Current foldback
functions are disabled during soft-start.
The LTC3854 has a minimum on-time at 75ns, making it
well suited for high step-down ratios. The strong onboard
MOSFET drivers allow the use of high power external
MOSFETs to produce output currents up to 20A.
L, LT, LTC, LTM, Linear Technology, the Linear logo and OPTI-LOOP are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners. Protected by U.S. Patents, including 5705919, 6498466, 5408150, 6222231.
TYPICAL APPLICATION
High Efficiency Synchronous Step-Down Converter
0.1µF
2200pF
10k
8.06k
42.2k
VIN
TG
LTC3854
RUN/SS BOOST
ITH SW
100pF
INTVCC
FB
SENSE
SENSE+
BG
GND
0.1µF
4.7µF
47µF
50V
VIN
6V TO 38V
4.7µH
AT 8.2mΩ DCR
5.49k 0.22µF
4.99k
VOUT
5V
+ 7A
150µF
Efficiency and Power Loss
vs Load Current
97 2.0
EFFICIENCY
96
1.6
95 1.2
94 0.8
POWER LOSS
93 0.4
92
1
VIN = 12V 0
234567
LOAD CURRENT (A)
3854 TA01b
3854 TA01
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LTC3854
LTC3854
ABSOLUTE MAXIMUM RATINGS (Note 1)
Input Supply Voltage (VIN)......................... 40V to –0.3V
Top Side Driver Voltage (BOOST)................ 46V to –0.3V
Switch Voltage (SW)................................... 40V to –5.0V
ISNETNVSCEC+,,
BOOST-SW.....................................
SENSE..........................................
6V
6V
to
to
0.3V
0.3V
RUN/SS......................................................... 6V to –0.3V
ITH, FB Voltages........................................ 2.7V to –0.3V
INTVCC Peak Output Current (Note 8).....................40mA
Operating Temperature Range
(Notes 2, 3)...........................................–40°C to 85°C
Maximum Junction Temperature....................... 125°C
Storage Temperature Range................... –65°C to 125°C
PIN CONFIGURATION
TOP VIEW
FB
ITH
RUN/SS
BOOST
TG
SW
1
2
3
4
5
6
12 SENSE+
11 SENSE
13 10 VIN
9 INTVCC
8 BG
7 GND
DDB PACKAGE
12-LEAD (3mm × 2mm) PLASTIC DFN
TJMAX = 125°C, θJA = 76°C/W, θJC = 10°C/W
EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB
FB 1
ITH 2
RUN/SS 3
BOOST 4
TG 5
SW 6
TOP VIEW
13
12 SENSE+
11 SENSE
10 VIN
9 INTVCC
8 BG
7 GND
MSE PACKAGE
12-LEAD PLASTIC MSOP
TJMAX = 125°C, θJA = 40°C/W, θJC = 16°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
LTC3854EDDB#PBF
LTC3854IDDB#PBF
LTC3854EDDB#TRPBF
LTC3854IDDB#TRPBF
LDPC
LDPC
12-Lead (3mm × 2mm) Plastic DFN
12-Lead (3mm × 2mm) Plastic DFN
–40°C to 85°C
–40°C to 85°C
LTC3854EMSE#PBF
LTC3854EMSE#TRPBF 3854
12-Lead Plastic MSOP
–40°C to 85°C
LTC3854IMSE#PBF
LTC3854IMSE#TRPBF 3854
12-Lead Plastic MSOP
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
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/
3854fb
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