LTC3860_15 Datasheet, PDF (1/36 Pages) Linear Technology – Dual, Multiphase Step-Down Voltage Mode DC/DC Controller with Current Sharing

LTC3860
FEATURES
Dual, Multiphase Step-Down
Voltage Mode DC/DC Controller
with Current Sharing
DESCRIPTION
n _{Operates with Power Blocks, DRMOS or External}
Gate Drivers and MOSFETs
n _{Constant Frequency Voltage Mode Control with}
Accurate Current Sharing
n _{±0.75% 0.6V Voltage Reference}
n _{Differential Remote Output Voltage Sense Amplifier}
n _{Multiphase Capability—Up to 12-Phase Operation}
n _{Programmable Current Limit}
n _{Safely Powers a Prebiased Load}
n _{Programmable or PLL-Synchronizable Switching}
Frequency Up to 1.25MHz
n _{Lossless Current Sensing Using Inductor DCR or}
Precision Current Sensing with Sense Resistor
n _{VCC Range: 3V to 5.5V}
n _{VIN Range: 3V to 24V}
n _{Power Good Output Voltage Monitor}
n _{Output Voltage Tracking Capability}
n _{Programmable Soft-Start}
n _{Available in a 32- Pin 5mm × 5mm QFN Package}
APPLICATIONS
n _{High Current Distributed Power Systems}
n _{Digital Signal Processor and ASIC Supplies}
n _{Telecom Systems}
n _{Industrial Power Supplies}
The LTC^®3860 is a dual, PolyPhase^® synchronous step-
down switching regulator controller for high current
distributed power systems, digital signal processors, and
other telecom and industrial DC/DC power supplies. It uses
a constant frequency voltage mode architecture combined
with very low offset, high bandwidth error amplifiers and
a remote output sense differential amplifier for excellent
transient response and output regulation.
The controller incorporates lossless inductor DCR current
sensing to maintain current balance between phases and to
provide overcurrent protection. The chip operates from a
V_CC supply between 3V and 5.5V and is designed for step-
down conversion from V_IN between 3V and 24V to output
voltages between 0.6V and V_CC – 0.5V.
The TRACK/SS pins provide programmable soft-start or
tracking functions. Inductor current reversal is disabled
during soft-start to safely power prebiased loads. The con-
stant operating frequency can be synchronized to an exter-
nal clock or linearly programmed from 250kHz to 1.25MHz.
Up to six LTC3860 controllers can operate in parallel for
1-, 2-, 3-, 4-, 6- or 12-phase operation.
The LTC3860 is available in a 32-pin 5mm × 5mm QFN
package.
L, LT, LTC, LTM, PolyPhase, μModule, Linear Technology and the Linear logo are registered
trademarks and No R_SENSE is a trademark of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Protected by U.S. Patents, including
6144194, 5055767
TYPICAL APPLICATION
V_IN
V_CC
V_OUT
1nF
20k 220Ω 33pF
20k _220pF
12.7k
470μF
1μF
0.1μF
PWM1
VINSNS
V_CC
FREQ
FB2
RUN1,2
I_LIM1
ISNS1P
I_LIM2
ISNS1N
FB1 ^LTC3860 ISNS2N
COMP1,2
ISNS2P
SS1,2
VSNSOUT
VSNSN
VSNSP
SGND
PWM2
I_AVG
CLKIN
PWM1
V_CC
50k
LTC4449
IN
GND
V_LOGIC TG
V_CC
TS
BOOST BG
0.22μF
0.22μF
0.22μF
PWM2
V_CC
100pF
LTC4449
IN
GND
V_LOGIC TG
V_CC
TS
BOOST BG
0.22μF
V_IN
TG1
SW1
0.3μH
BG1
2.32k
V_IN
2.32k
TG2
SW2
0.3μH
BG2
V_OUT
1.2V
330μF 50A
s4
3860 TA01
3860fc
1