LTC3861 Dual, Multiphase Step-Down Voltage Mode DC/DC Controller with Accurate Current Sharing Fea T Descrip T 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 CapabilityUp 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 V supply between 3V and 5.5V and is designed for step- CC Precision Current Sensing with Sense Resistor down conversion from V between 3V and 24V to output IN n V Range: 3V to 5.5V CC voltages between 0.6V and V 0.5V. CC n V Range: 3V to 24V IN n The TRACK/SS pins provide programmable soft-start or Power Good Output Voltage Monitor n tracking functions. Inductor current reversal is disabled Output Voltage Tracking Capability n during soft-start to safely power prebiased loads. The Programmable Soft-Start n constant operating frequency can be synchronized to an Available in a 36-Pin 5mm 6mm QFN Package external clock or linearly programmed from 250kHz to a T 2.25MHz. Up to six LTC3861 controllers can operate in parallel for 1-, 2-, 3-, 4-, 6- or 12-phase operation. n 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 V , 7V TO 14V IN Typical a T LTC4449 180F V IN IN GND TG1 V V TG CC LOGIC SW1 V TS CC V CC V VINSNS PWM1 CC 0.47H BOOST BG FREQ 1F BG1 FB2 28k LTC3861 59k 0.22F RUN1,2 I LIM2 2.87k I LIM1 VSNSOUT1 ISNS1P 0.22F V OUT V OUT VSNSP1 ISNS1N 1.2V VSNSN1 330F 100F ISNS2N 60A 10k VSNSOUT2 0.22F 6 4 ISNS2P VSNSP2 V IN 2.87k 3.3nF VSNSN2 10k LTC4449 CONFIG PWM2 IN GND TG2 10k 280 0.47H FB1 V V TG CC LOGIC I AVG SW2 3861 TA01 V TS CC COMP1,2 SS1,2 SGND CLKIN BOOST BG 4.7nF BG2 5.9k 100pF 100pF 0.1F 0.22F 3861fb 1 For more information www.linear.com/LTC3861 ion pplica ions pplica ion uresLTC3861 a Te m aximum r a T p in c F T (Note 1) V Voltage .................................................. 0.3V to 6V CC TOP VIEW VINSNS Voltage ......................................... 0.3V to 30V RUN1, RUN2 Voltage ........................0.3V to V + 0.3V CC ISNS1P, ISNS1N, 36 35 34 33 32 31 30 29 ISNS2P, ISNS2N ........................... 0.3V to (V + 0.1V) CC FB1 1 28 RUN1 All Other Pins ................................0.3V to (V + 0.3V) CC COMP1 2 27 I LIM1 Operating Junction Temperature Range VSNSP1 3 26 SGND (Notes 2, 3) ............................................ 40C to 125C VSNSN1 4 25 ISNS1P 37 VSNSOUT1 5 24 ISNS1N Storage Temperature Range .................. 65C to 150C SGND VSNSOUT2 6 23 ISNS2N VSNSN2 7 22 ISNS2P VSNSP2 8 21 SGND COMP2 9 20 I LIM2 FB2 10 19 RUN2 11 12 13 14 15 16 17 18 UHE PACKAGE 36-LEAD (5mm 6mm) PLASTIC QFN T = 125C, = 43C/W JMAX JA EXPOSED PAD (PIN 37) IS SGND, MUST BE SOLDERED TO PCB o r Der i n F T LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3861EUHE PBF LTC3861EUHE TRPBF 3861 36-Lead (5mm 6mm) Plastic QFN 40C to 125C LTC3861IUHE PBF LTC3861IUHE TRPBF 3861 36-Lead (5mm 6mm) Plastic QFN 40C to 125C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: