LTC3732 3-Phase, 5-Bit VID, 600kHz, Synchronous Buck Switching Regulator Controller FEATURES DESCRIPTIO n 3-Phase Current Mode Controller with The LTC 3732 is a PolyPhase synchronous step-down Onboard MOSFET Drivers switching regulator controller that drives all N-channel n 5% Output Current Matching Optimizes Thermal external power MOSFET stages in a phase-lockable fixed Performance and Size of Inductors and MOSFETs frequency architecture. The 3-phase controller drives its n 4.5V V 7V 4.5V V 32V output stages with 120 phase separation at frequencies CC IN n Differential Amplifier Accurately Senses V of up to 600kHz per phase to minimize the RMS current OUT n Reduced Input and Output Capacitance losses in both the input and output filter capacitors. The 3- n Reduced Power Supply Induced Noise phase technique effectively triples the fundamental fre- n VID DAC Programmable from 1.1V to 1.85V quency, improving transient response while operating (VRM9.0/9.1) each controller at an optimal frequency for high efficiency n 10% Power Good Output Indicator and ease of thermal design. Light load efficiency is opti- n 250kHz to 600kHz Per Phase, PLL, Fixed Frequency mized by using a choice of output Stage Shedding or Burst TM n PWM, Stage Shedding or Burst Mode Operation Mode technology. n OPTI-LOOP Compensation Minimizes C OUT A differential amplifier provides true remote sensing of both n Adjustable Soft-Start Current Ramping the high and low side of the output voltage at load points. n Short-Circuit Shutdown Timer with Defeat Option n Overvoltage Soft Latch Soft-start and a defeatable, timed short-circuit shutdown n Small 36-Lead Narrow (0.209 ) SSOP Package protect the MOSFETs and the load. A foldback current n QFN 5mm 7mm 38-Lead Package circuit also provides protection for the external MOSFETs U under short-circuit or overload conditions. APPLICATIO S n , LTC and LT are registered trademarks of Linear Technology Corporation. Desktop Computers Burst Mode, OPTI-LOOP and PolyPhase are registered trademarks of Linear Technology n High Performance Notebook Computers Corporation. Stage Shedding is a trademark of Linear Technology Corporation n High Output Current DC/DC Power Supplies TYPICAL APPLICATIO V IN V 5V TO 28V CC V TG1 CC + 1H 4.5V TO 7V 0.003 22F LTC3732 10F SW1 35V BOOST1 BG1 BOOST2 BOOST3 + 0.1F SENSE1 SENSE1 SW3 SW2 SW1 V IN TG2 1H POWER GOOD INDICATOR PGOOD V 0.003 OUT OPTIONAL SYNC IN PLLIN SW2 1.1V TO 1.85V 55A BG2 PLLFLTR PGND 5 VID BITS VID0-VID4 + SENSE2 680pF SENSE2 V IN I TG3 TH 1H 0.003 5k RUN/SS SW3 0.1F SGND BG3 EAIN + 100pF SENSE3 SENSE3 IN + C OUT + IN 470F 4V 3732 F01 Figure 1. High Current Triple Phase Step-Down Converter 3732f 1 U ULTC3732 ABSOLUTE AXI U RATI GS (Note 1) Topside Driver Voltages (BOOST ) ............ 38V to 0.3V Operating Ambient Temperature Range ....... 0 C to 70 C N Switch Voltage (SW )................................... 32V to 5V Junction Temperature (Notes 2, 3, 7) ................... 125 C N Boosted Driver Voltage (BOOST SW ) .... 7V to 0.3V Storage Temperature Range ..................65 C to 150 C N N Peak Output Current <1ms (TG , BG ) ..................... 5A Lead Temperature (Soldering, 10 sec) N N Supply Voltage (V ), PGOOD SSOP Package .................................................. 300 C CC Pin Voltage .................................................. 7V to 0.3V Reflow Peak Body Temperature RUN/SS, PLLFLTR, PLLIN, FCB Voltages .. V to 0.3V QFN Package .................................................... 240 C CC I Voltage ................................................ 2.4V to 0.3V TH UUW PACKAGE/ORDER I FOR ATIO TOP VIEW ORDER PART TOP VIEW ORDER PART VID1 1 36 VID0 NUMBER NUMBER PLLIN 2 35 PGOOD 3 BOOST1 38 37 36 35 34 33 32 PLLFLTR 34 LTC3732CG LTC3732CUHF + IN 1 31 TG1 FCB 4 33 TG1 + IN 2 30 SW1 5 32 SW1 IN DIFFOUT 3 29 BOOST2 IN 6 31 BOOST2 EAIN 4 28 TG2 DIFFOUT 7 30 TG2 PADDLE 5 27 SW2 8 SW2 EAIN 29 UNDERSIDE SGND 6 26 V CC PADDLE SGND 9 28 V CC + SENSE1 7 IS SGND 25 DRV CC + 10 27 BG1 SENSE1 SENSE1 8 24 BG1 SENSE1 11 26 PGND + SENSE2 9 23 PGND + SENSE2 12 25 BG2 SENSE2 10 22 BG2 13 24 BG3 SENSE2 SENSE3 11 21 BG3 + SENSE3 14 23 SW3 SENSE3 12 20 SW3 + 15 22 TG3 SENSE3 13 14 15 16 17 18 19 RUN/SS 16 21 BOOST3 I 17 20 VID4 TH 18 19 VID3 VID2 UHF PACKAGE 38-LEAD (7mm 5mm) PLASTIC QFN PADDLE IS SGND G PACKAGE 36-LEAD PLASTIC SSOP (MUST BE CONNECTED TO PCB AND SGND PIN) T = 125 C, q = 34 C/W T = 125 C, q = 95 C/W JMAX JA JMAX JA Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25 C. V = V = 5V unless otherwise noted. A CC RUN/SS SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Main Control Loop + V Regulated Voltage at IN (Note 3) VID Code = 11111, V = 1.2V 1.067 1.075 1.083 V REGULATED ITH l 1.064 1.075 1.086 V V Maximum Current Sense Threshold V = 0.5V, V Open, 65 75 85 mV SENSEMAX EAIN ITH V V V = 0.6V, 1.8V l 62 75 88 mV SENSE1 , SENSE2 , SENSE3 I Current Match Worst-Case Error at V 5 5 % MATCH SENSE MAX V Output Voltage Load Regulation (Note 3) LOADREG Measured in Servo Loop, D I Voltage = 1.2V to 0.7V l 0.1 0.5 % TH Measured in Servo Loop, D I Voltage = 1.2V to 2V l 0.1 0.5 % TH V Output Voltage Line Regulation V = 4.5V to 7V 0.03 %/V REFLNREG CC 3732f 2 RUN/SS FCB I PLLFLTR TH PLLIN VID2 VID1 VID3 VID4 VID0 BOOST3 PGOOD TG3 BOOST1 U WWW