POWER LOSS (W) LTC3875 Dual, 2-Phase, Synchronous Controller with Low Value DCR Sensing and Temperature Compensation FEATURES DESCRIPTION n Low Value DCR Current Sensing The LTC 3875 a dual output current mode synchronous n Programmable DCR Temperature Compensation step-down DC/DC controller that drives all N-channel n 0.5% 0.6V Output Voltage Accuracy power MOSFET stages. It employs a unique architecture n Dual True Remote Sensing Differential Amplifiers that enhances the signal-to-noise ratio of the current sense n Phase-Lockable Fixed Frequency 250kHz to 720kHz signal, allowing the use of very low DC resistance (DCR) n power inductors to maximize efficiency in high current Dual, 180 Phased Controllers Reduce Required Input Capacitance and Power Supply Induced Noise applications. This feature also reduces the switching jitter n commonly found in low DCR applications with current Dual N-Channel MOSFET Synchronous Drive n Wide V Range: 4.5V to 38V Operation mode control. IN n Output Voltage Range with Low DCR: 0.6V to 3.5V, The LTC3875 features two high speed differential amplifiers without Low DCR: 0.6V to 5V which can be used to compensate for the voltage drop from n Adjustable Soft-Start Current Ramping or Tracking the LTC3875 to the load. Its DCR temperature compensated n Foldback Output Current Limiting adjustable over current trip points from 10mV to 30mV limits n Clock Input and Output for Up to 12-Phase Operation the maximum output current precisely over temperature. n Short-Circuit Soft Recovery A unique thermal balancing function adjusts per phase n Output Overvoltage Protection current to minimize the thermal stress for multichip single n Power Good Output Voltage Monitor output applications. The LTC3875 is available in the 40- n 40-Lead QFN Packages lead 6mm 6mm (0.5mm pitch) and 40-lead 5mm 5mm n AEC-Q100 Qualification in Progress (0.4mm pitch) QFN packages. 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Protected APPLICATIONS by U.S. Patents including 5481178, 5705919, 5929620, 6100678, 6144194, 6177787, 6304066, 6580258. n Servers and Instruments n Telecom Systems n DC Power Distribution Systems TYPICAL APPLICATION High Efficiency Dual Phase 1.2V/60A Step-Down Converter V IN 6V TO 14V INTV 22F Efficiency and Power Loss CC 16V 4 4.7F V INTV PHASMD IN CC vs Load Current CLKOUT (OPTIONAL) (OPTIONAL) RUN1,2 PGOOD 100 14 IFAST ILIM 12V THERMAL THERMAL IN ENTMPB MODE/PLLIN 1.8V SENSOR SENSOR O 12 TG1 TG2 95 ~400kHz 0.3H 0.3H CCM BOOST1 BOOST2 (0.32m DCR) (0.32m DCR) 10 90 SW1 LTC3875 SW2 EXTV CC 8 BG1 BG2 85 TAVG PGND 6 TRSET1 TRSET2 + SNSA1 80 + SNSA2 4 SNS1 SNS2 0.32m + SNSD1 + SNSD2 75 1.5m 2 TCOMP1 0.32m PLOSS TCOMP2 + V V OUT OSNS1 V 1.5m PLOSS FREQ 20k OUT V + 70 0 OSNS1 1.2V V OSNS2 0 10 20 30 40 50 60 I TH1 V 60A + 470F OSNS2 1500pF LOAD CURRENT (A) TK/SS1 TK/SS2 I 2.5V 2 TH2 + 470F 20k SP 3875 TA01b 122k 15k 2.5V 2 0.1F SP 3875 TA01a Rev. C 1 Document Feedback For more information www.analog.com EFFICIENCY (%)LTC3875 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Supply Voltage (V ) ......................... 40V to 0.3V MODE/PLLIN, ILIM, FREQ, IFAST, ENTMPB IN + Topside Driver Voltages V , V Voltages ...............INTV to 0.3V OSNS(s) OSNS(s) CC (BOOST1, BOOST2).................................... 46V to 0.3V I , I , PHASMD, TRSET1, TRSET2, TH1 TH2 Switch Voltage (SW1, SW2) .......................... 40V to 5V TCOMP1, TCOMP2, TAVG Voltages .......INTV to 0.3V CC INTV , RUN(s), PGOOD, EXTV INTV Peak Output Current ................................100mA CC CC CC (BOOST-SW1), (BOOST2-SW2).................... 6V to 0.3V Operating Junction Temperature Range + + SNSA (s), SNSD (s), (Notes 2, 3) ............................................ 40C to 125C SNS (s) Voltages ..................................INTV to 0.3V Storage Temperature Range .................. 65C to 125C CC PIN CONFIGURATION TOP VIEW TOP VIEW 40 39 38 37 36 35 34 33 32 31 40 39 38 37 36 35 34 33 32 31 TK/SS1 1 30 SW1 TK/SS1 1 30 SW1 + + V 2 29 TG1 V 2 29 TG1 OSNS1 OSNS1 V 3 28 BOOST1 V 3 28 BOOST1 OSNS1 OSNS1 I 4 27 BG1 I 4 27 BG1 TH1 TH1 I I 5 26 V 5 26 V TH2 IN TH2 IN 41 41 + + SGND/PGND SGND/PGND V 6 25 INTV V 6 25 INTV OSNS2 OSNS2 CC CC V 7 24 EXTV V 7 24 EXTV OSNS2 CC OSNS2 CC TK/SS2 8 23 BG2 TK/SS2 8 23 BG2 + + SNSA2 9 22 BOOST2 SNSA2 9 22 BOOST2 SNS2 10 21 SNS2 10 21 TG2 TG2 11 12 13 14 15 16 17 18 19 20 11 12 13 14 15 16 17 18 19 20 UJ PACKAGE UH PACKAGE 40-LEAD (6mm 6mm) PLASTIC QFN 40-LEAD (5mm 5mm) PLASTIC QFN T = 125C, = 33C/W, = 2.0C/W T = 125C, = 44C/W, = 7.3C/W JMAX JA JC JMAX JA JC EXPOSED PAD (PIN 41) IS SGND/PGND, MUST BE SOLDERED TO PCB EXPOSED PAD (PIN 41) IS SGND/PGND, MUST BE SOLDERED TO PCB Rev. C 2 For more information www.analog.com + + SNSD2 SNSA1 TCOMP2/ITEMP2 SNS1 + TAVG SNSD1 TRSET2 TCOMP1/ITEMP1 FREQ TRSET1 RUN2 ILIM IFAST RUN1 ENTMPB MODE/PLLIN PGOOD PHASMD SW2 CLKOUT + + SNSD2 SNSA1 TCOMP2/ITEMP2 SNS1 + TAVG SNSD1 TRSET2 TCOMP1/ITEMP1 FREQ TRSET1 RUN2 ILIM IFAST RUN1 ENTMPB MODE/PLLIN PGOOD PHASMD SW2 CLKOUT