Datasheet LTC3861-1 (Analog Devices)

LTC3861-1 Dual, Multiphase Step-Down Voltage Mode DC/DC Controller with Accurate Current Sharing
FeaTures DescripTion
n
Operates with Power Blocks, DrMOS or External
The LTC®3861-1 is a dual PolyPhase® synchronous step-
Gate Drivers and MOSFETs
down switching regulator controller for high current n
Constant-Frequency Voltage Mode Control with
distributed power systems, digital signal processors, and
Accurate Current Sharing
other telecom and industrial DC/DC power supplies. It uses n
±0.75% 0.6V Voltage Reference
a constant-frequency voltage mode architecture combined n
Differential Remote Output Voltage Sense Amplifier
with very low offset, high bandwidth error amplifiers and n
Multiphase Capability—Up to 12-Phase Operation
a remote output sense differential amplifier for excel ent n
Programmable Current Limit
transient response and output regulation. n
Safely Powers a Prebiased Load
The controller incorporates lossless inductor DCR current n
Programmable or PLL-Synchronizable Switching
sensing to maintain current balance between phases and to
Frequency Up to 2.25MHz
provide overcurrent protection. The chip operates from a n
Lossless Current Sensing Using Inductor DCR or
VCC supply between 3V and 5.5V and is designed for step-
Precision Current Sensing with Sense Resistor
down conversion from VIN between 3V and 24V to output n VCC Range: 3V to 5.5V voltages between 0.6V and VCC – 0.5V. n VIN Range: 3V to 24V n Inductor current reversal is disabled during soft-start to Power Good Output Voltage Monitor n safely power prebiased loads. The constant operating Output Voltage Tracking Capability n frequency can be synchronized to an external clock or Programmable Soft-Start n linearly programmed from 250kHz to 2.25MHz. Up to six Available in a 32-Pin 5mm × 5mm QFN Package LTC3861-1 controllers can operate in parallel for 1-, 2-, 3-, 4-, 6- or 12-phase operation.
applicaTions
n The LTC3861-1 is pin-to-pin compatible with the LTC3860. High Current Distributed Power Systems n It is available in a 32-pin 5mm × 5mm QFN package. The DSP, FPGA and ASIC Supplies n LTC3861is a 36-pin QFN version of the LTC3861-1, which Datacom and Telecom Systems has dual differential output voltage sense amplifiers. n Industrial Power Supplies L, LT, LTC, LTM, PolyPhase, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 6144194, 5055767
Typical applicaTion
VIN, 7V TO 14V LTC4449 180µF IN GND VIN, 7V TO 14V V V CC LOGIC TG VCC V V TS CC VINSNS CC PWM1 0.47µH 1µF FREQ BOOST BG 28.7k FB2 LTC3861-1 59k I 0.22µF LIM2 RUN1,2 2.87k ILIM1 VSNSOUT ISNS1P 0.22µF VOUT VOUT VSNSP ISNS1N 1.2V VSNSN ISNS2N 330µF 100µF 60A CONFIG ISNS2P 0.22µF × 6 × 4 VIN 1nF 2.87k LTC4449 PWM2 20k 221Ω IN GND FB1 V I CC VLOGIC TG 0.47µH AVG V TS 38611 TA01 COMP1,2 SS1,2 SGND CLKIN CC 1nF BOOST BG 20k 13k 220pF 0.1µF 100pF 0.22µF 38611fb For more information www.linear.com/LTC3861-1 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Package Description Related Parts