LTC3860
Dual, Multiphase Step-Down
Voltage Mode DC/DC Controller
with Current Sharing
FeaTures
DescripTion
The LTC®3860 is a dual, PolyPhase® synchronous step-
down switching regulator controller for high current
distributed power systems, digital signal processors, and
othertelecomandindustrialDC/DCpowersupplies.Ituses
aconstantfrequencyvoltagemodearchitecturecombined
with very low offset, high bandwidth error amplifiers and
a remote output sense differential amplifier for excellent
transient response and output regulation.
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Constant Frequency Voltage Mode Control with
Accurate Current Sharing
±±0.75 ±0ꢀV Voltage Reference
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Differential Remote Output Voltage Sense Amplifier
Multiphase Capability—Up to 12-Phase Operation
Programmable Current Limit
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Safely Powers a Pre-Biased Load
Programmable or PLL-Synchronizable Switching
Frequency Up to 1027MHz
ThecontrollerincorporateslosslessinductorDCRcurrent
sensingtomaintaincurrentbalancebetweenphasesandto
provide overcurrent protection. The chip operates from a
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Lossless Current Sensing Using Inductor DCR or
Precision Current Sensing with Sense Resistor
Fast and Accurate True Operational Error Amplifiers
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V
supply between 3V and 5.5V and is designed for step-
CC
V
Range: 3V to 5.5V
CC
down conversion from V between 3V and 24V to output
IN
V Range: 3V to 24V
IN
voltages between 0.6V and V – 0.5V.
CC
Power Good Output Voltage Monitor
Output Voltage Tracking Capability
Programmable Soft-Start
The TRACK/SS pins provide programmable soft-start or
tracking functions. Inductor current reversal is disabled
duringsoft-starttosafelypowerprebiasedloads.Thecon-
stantoperatingfrequencycanbesynchronizedtoanexter-
nalclockorlinearlyprogrammedfrom250kHzto1.25MHz.
Up to six LTC3860 controllers can operate in parallel for
1-, 2-, 3-, 4-, 6- or 12-phase operation.
Available in a 32- Pin 5mm × 5mm QFN Package
applicaTions
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High Current Distributed Power Systems
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Digital Signal Processor and ASIC Supplies
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The LTC3860 is available in a 32-pin 5mm × 5mm QFN
package.
Telecom Systems
Industrial Power Supplies
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L, LT, LTC, LTM, PolyPhase, µModule, Linear Technology and the Linear logo are registered
trademarks and No R
is a trademark of Linear Technology Corporation. All other
SENSE
trademarks are the property of their respective owners. Protected by U.S. Patents, including
6144194, 5055767
Typical applicaTion
V
IN
TG1
LTC4449
GND
PWM1
IN
V
0.3µH
TG
TS
BG
V
LOGIC
CC
BOOST
CC
V
IN
SW1
V
470µF
PWM1
BG1
VINSNS
50k
0.22µF
V
RUN1,2
LIM1
ISNS1P
ISNS1N
ISNS2N
ISNS2P
V
CC
CC
2.32k
FREQ
FB2
I
1µF
V
1.2V
50A
0.22µF
0.22µF
PWM2
OUT
V
OUT
I
LIM2
FB1
LTC3860
330µF
s4
COMP1,2
SS1,2
1nF
V
IN
2.32k
0.3µH
LTC4449
33pF
20k 220Ω
VSNSOUT
VSNSN
VSNSP
SGND
PWM2
IN
V
V
GND
TG
TG2
V
CC
LOGIC
CC
BOOST
I
SW2
AVG
3860 TA01
TS
0.1µF
20k
CLKIN
220pF
BG
12.7k
BG2
100pF
0.22µF
3860f
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