LTC3862
Multi-Phase Current Mode
Step-Up DC/DC Controller
FEATURES
DESCRIPTION
The LTC®3862 is a two phase constant frequency, current
mode boost and SEPIC controller that drives N-channel
power MOSFETs. Two phase operation reduces system
filteringcapacitanceandinductancerequirements.The5V
gate drive is optimized for most automotive and industrial
grade power MOSFETs.
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Wide V Range: 4V to 36V Operation
IN
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2-Phase Operation Reduces Input and Output
Capacitance
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Fixed Frequency, Peak Current Mode Control
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5V Gate Drive for Logic-Level MOSFETs
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Adjustable Slope Compensation Gain
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Adjustable Max Duty Cycle (Up to 96%)
Adjustableslopecompensationgainallowstheusertofine-
tune the current loop gain, improving noise immunity.
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Adjustable Leading Edge Blanking
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1ꢀ Internal Voltage Reference
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Theoperatingfrequencycanbesetwithanexternalresistor
over a 75kHz to 500kHz range and can be synchronized
to an external clock using the internal PLL. Multi-phase
operation is possible using the SYNC input, the CLKOUT
output and the PHASEMODE control pin allowing 2-, 3-,
4-, 6- or 12-phase operation.
Programmable Operating Frequency with One
External Resistor (75kHz to 500kHz)
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Phase-Lockable Fixed Frequency 50kHz to 650kHz
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SYNC Input and CLKOUT for 2-, 3-, 4-, 6- or
12-Phase Operation (PHASEMODE Programmable)
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Internal 5V LDO Regulator
24-Lead Narrow SSOP Package
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Otherfeaturesincludeaninternal5VLDOwithundervoltage
lockout protection for the gate drivers, a precision RUN
pin threshold with programmable hysteresis, soft-start
and programmable leading edge blanking and maximum
duty cycle
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5mm × 5mm QFN with 0.65mm Lead Pitch and
24-Lead Thermally Enhanced TSSOP Packages
APPLICATIONS
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Automotive, Telecom and Industrial Power Supplies
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents,
including 6144194, 6498466, 6611131.
TYPICAL APPLICATION
V
IN
5V TO 36V
22μF
50V
84.5k
19.4μH 19.4μH
V
OUT
48V
Efficiency vs Output Current
V
24.9k
IN
5A (MAX)
RUN
INTV
GATE1
+
98
96
94
92
90
88
86
84
82
80
V
= 48V
OUT
SENSE1
CC
V
= 12V
220μF
50V
IN
4.7μF
10nF
0.006Ω
LTC3862
–
BLANK
FREQ
SENSE1
66.5k
10k
GATE2
SYNC
+
SENSE2
V
= 24V
IN
PLLFLTR
10nF
0.006Ω
V
IN
= 5V
SS
–
SENSE2
1nF
3V8
PGND
CLKOUT
SLOPE
FB
10nF
68.1k
D
MAX
ITH
PHASEMODE
SGND
100
1000
LOAD CURRENT (mA)
10000
475k
12.4k
100pF
3862 TA01b
3862 TA01
3862fb
1