LTC3719 2-Phase, High Efficiency, Step-Down Controller for AMD Opteron CPUs DESCRIPTIO FEATURES n Output Stages Operate Antiphase Reducing Input The LTC 3719 is a 2-phase, VID programmable, synchro- and Output Capacitance Requirements and Power nous step-down switching regulator controller that drives Supply Induced Noise two N-channel external power MOSFET stages in a fixed fre- n Dual Input Supply Capability for Load Sharing quency architecture. The 2-phase controller drives its two n 5-Bit AMD CPU VID Code: output stages out of phase at frequencies up to 300kHz to V = 0.8V to 1.55V minimize the RMS ripple currents in both input and output OUT n 1% Output Voltage Accuracy capacitors. The 2-phase technique effectively multiplies the n True Remote Sensing Differential Amplifier fundamental frequency by two, improving transient re- n Power Good Output Voltage Monitor sponse while operating each channel at an optimum fre- n Supports Active Voltage Positioning quency for efficiency. Thermal design is also simplified. n Current Mode Control Ensures Current Sharing An operating mode select pin (FCB) can be used to select n OPTI-LOOP Compensation Minimizes C OUT among three modes including Burst Mode operation for n Three Operational Modes: PWM, Burst and Cycle Skip highest efficiency. An internal differential amplifier provides n Programmable Fixed Frequency: 150kHz to 300kHz true remote sensing of the regulated supplys positive and n Wide V Range: 4V to 36V Operation IN negative output terminals as required in high current ap- n Adjustable Soft-Start Current Ramping plications. n Internal Current Foldback and Short-Circuit Shutdown n The RUN/SS pin provides soft-start and optional timed, Overvoltage Soft Latch Eliminates Nuisance Trips n short-circuit shutdown. Current foldback limits MOSFET Available in 36-Lead Narrow (0.209) SSOP Package U dissipation during short-circuit conditions when the APPLICATIO S overcurrent latchoff is disabled. OPTI-LOOP compensation allows the transient response to be optimized for a wide n Servers and Workstations range of output capacitors and ESR values. , LTC and LT are registered trademarks of Linear Technology Corporation. OPTI-LOOP and Burst Mode are registered trademarks of Linear Technology Corporation. AMD Opteron is a trademark of Advanced Micro Devices, Inc. TYPICAL APPLICATIO V IN 5V TO 28V 10F 35V 0.1F V FCB IN TG1 6 0.002 RUN/SS BOOST1 0.47F 220pF SW1 1H 3.3k LTC3719 D1 I BG1 TH PGND SGND + PGOOD SENSE1 SENSE1 5 VID BITS VID0VID4 TG2 V 0.002 DD CORE EAIN BOOST2 0.47F 0.8V TO 1.55V ATTENOUT SW2 1H 45A D2 ATTENIN BG2 V INTV DIFFOUT CC C OUT + + V SENSE2 OS 270F 10F + 2V V SENSE2 OS 4 3716 F01 Figure 1. High Current Dual Phase Step-Down Converter sn3719 3719fs 1 + S S U ULTC3719 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) TOP VIEW ORDER PART Input Supply Voltage (V ).........................36V to 0.3V IN RUN/SS 1 36 PGOOD NUMBER Topside Driver Voltages (BOOST1,2).........42V to 0.3V + SENSE1 2 35 TG1 Switch Voltage (SW1, 2) .............................36V to 5 V LTC3719EG SENSE1 3 34 SW1 + + SENSE1 , SENSE2 , SENSE1 , EAIN 4 33 BOOST1 SENSE2 Voltages ................... (1.1)INTV to 0.3V CC 5 32 V PLLFLTR IN + EAIN, V , V , EXTV , INTV , RUN/SS, OS OS CC CC 6 31 BG1 PLLIN V , ATTENIN, ATTENOUT, PGOOD, NO CPU, BIAS 7 30 EXTV FCB CC VID0VID4, Voltages ...............................7V to 0.3V 8 29 INTV I CC TH Boosted Driver Voltage (BOOST-SW) ..........7V to 0.3V 9 28 PGND SGND PLLFLTR, PLLIN, V , DIFFOUT 10 27 BG2 V DIFFOUT FCB Voltages ................................... INTV to 0.3V 11 26 BOOST2 CC V OS + I Voltage ................................................2.7V to 0.3V 12 25 SW2 V TH OS 13 24 TG2 Peak Output Current <1m s(TG1, 2, BG1, 2)................ 3A SENSE2 + 14 23 ATTENIN SENSE2 INTV RMS Output Current................................ 50mA CC 15 22 V ATTENOUT BIAS Operating Ambient Temperature Range 16 21 VID4 NO CPU (Note 2) .............................................. 40 C to 85 C 17 20 VID3 VID0 Junction Temperature (Note 3)............................. 125 C 18 19 VID2 VID1 Storage Temperature Range ................. 65 C to 150 C G PACKAGE Lead Temperature (Soldering, 10 sec).................. 300 C 36-LEAD PLASTIC SSOP T = 125 C, q = 85 C/W 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 = 15V, V = 5V, V = 5V unless otherwise noted. A IN BIAS RUN/SS SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Main Control Loop V Regulated Feedback Voltage I Voltage = 1.2V Measured at V (Note 4) l 0.594 0.600 0.606 V EAIN TH EAIN V Maximum Current Sense Threshold l 62 75 88 mV SENSEMAX I Feedback Current (Note 4) 5 50 nA INEAIN V Output Voltage Load Regulation (Note 4) 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 Reference Voltage Line Regulation V = 3.6V to 30V (Note 4) 0.002 0.02 %/V REFLNREG IN V Forced Continuous Threshold l 0.57 0.6 0.63 V FCB I Forced Continuous Current 0.17 1 m A FCB V Burst Inhibit (Constant Frequency) Measured at FCB pin 4.3 4.8 V BINHIBIT Threshold V Output Overvoltage Threshold Measured at V l 0.64 0.66 0.68 V OVL EAIN UVLO Undervoltage Lockout V Ramping Down 3 3.33 4 V IN g Transconductance Amplifier g I = 1.2V, Sink/Source 5m A (Note 4) 3 mmho m m TH g Transconductance Amplifier Gain I = 1.2V, (g Z No Ext Load) (Note 4) 1.5 V/mV mOL TH m L sn3719 3719fs 2 U WWW