Datasheet LTC3861 (Analog Devices)

LTC3861 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 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
Dual Differential Output Voltage Sense Amplifiers
with very low offset, high bandwidth error amplifiers and a n
Multiphase Capability—Up to 12-Phase Operation
remote output sense differential amplifier per channel for n
Programmable Current Limit
excellent 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 V n IN between 3V and 24V to output VCC Range: 3V to 5.5V voltages between 0.6V and V n CC – 0.5V. VIN Range: 3V to 24V n Power Good Output Voltage Monitor The TRACK/SS pins provide programmable soft-start or n Output Voltage Tracking Capability tracking functions. Inductor current reversal is disabled n Programmable Soft-Start during soft-start to safely power prebiased loads. The n Available in a 36-Pin 5mm × 6mm QFN Package constant operating frequency can be synchronized to an external clock or linearly programmed from 250kHz to
applicaTions
2.25MHz. Up to six LTC3861 controllers can operate in n parallel for 1-, 2-, 3-, 4-, 6- or 12-phase operation. High Current Distributed Power Systems n DSP, FPGA and ASIC Supplies The LTC3861 is available in a 36-pin 5mm × 6mm QFN pack- n Datacom and Telecom Systems age. LTC3861-1 is a 32-pin QFN version of the LTC3861, n Industrial Power Supplies which has a single differential remote output voltage sense L, LT, LTC, LTM, PolyPhase, Linear Technology and the Linear logo are registered trademarks amplifier. 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 VIN IN GND TG1 V V CC LOGIC TG SW1 VCC V V TS CC VINSNS CC PWM1 0.47µH 1µF FREQ BOOST BG BG1 28k FB2 LTC3861 59k I 0.22µF LIM2 RUN1,2 2.87k ILIM1 VSNSOUT1 ISNS1P 0.22µF V V OUT OUT VSNSP1 ISNS1N 1.2V VSNSN1 ISNS2N 10k 330µF 100µF 60A VSNSOUT2 ISNS2P 0.22µF × 6 × 4 VSNSP2 VIN 3.3nF VSNSN2 2.87k 10k LTC4449 CONFIG PWM2 10k 280Ω IN GND TG2 FB1 V I CC VLOGIC TG 0.47µH AVG V TS SW2 3861 TA01 COMP1,2 SS1,2 SGND CLKIN CC 4.7nF BOOST BG 5.9k 100pF 0.1µF 100pF BG2 0.22µF 3861fb For more information www.linear.com/LTC3861 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