LTC1709-8/LTC1709-9 2-Phase, 5-Bit VID, Current Mode, High Efficiency, Synchronous Step-Down Switching Regulators FEATURES DESCRIPTIO n Single Controller Operates Two Output Stages The LTC 1709-8/LTC1709-9 are 2-phase, VID program- Antiphase Reducing Required Input Capacitance mable, synchronous step-down switching regulator con- and Power Supply Induced Noise trollers that drive two all N-channel external power MOSFET n Two 5-Bit Desktop VID Codes: stages in a fixed frequency architecture. The 2-phase LTC1709-8 For VRM8.4 (V from 1.3V to 3.5V) controller drives its two output stages out of phase at OUT LTC1709-9 For VRM9.0 (V from 1.1V to 1.85V) frequencies from 150kHz to 300kHz to minimize the RMS OUT n Current Mode Control Ensures Best Current Sharing ripple currents in both input and output capacitors. The 2- n True Remote Sensing Differential Amplifier phase technique effectively multiplies the fundamental n Power Good Output Indicator frequency by two, improving transient response while TM n OPTI-LOOP Compensation Minimizes C operating each channel at an optimum frequency for OUT n Programmable Fixed Frequency: 150kHz to 300kHz efficiency. Thermal design is also simplified. n 1% Output Voltage Accuracy An internal differential amplifier provides true remote n Wide V Range: 4V to 36V Operation IN sensing of the regulated supplys positive and negative n Adjustable Soft-Start Current Ramping output terminals as required for high current applications. 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 Low Shutdown Current: 20m A n dissipation during short-circuit conditions when the Available in 36-Lead Narrow SSOP Package overcurrent latchoff is disabled. OPTI-LOOP compensa- U tion allows the transient response to be optimized for a APPLICATIO S wide range of output capacitors and ESR values. The n Workstations LTC1709-8/LTC1709-9 implement two different VID n Internet Servers tables compliant with VRM8.4 and VRM9.0 respectively. n Large Memory Arrays , LTC and LT are registered trademarks of Linear Technology Corporation. n DC Power Distribution Systems OPTI-LOOP is a trademark of Linear Technology Corporation. TYPICAL APPLICATION V IN 5V TO 28V + 10F 35V 0.1F V IN TG1 4 0.002 RUN/SS BOOST1 0.47F 220pF SW1 1H 3.3k LTC1709-8 I BG1 TH SGND PGND + PGOOD SENSE1 SENSE1 5 VID BITS VID0VID4 TG2 0.002 V OUT EAIN BOOST2 0.47F 1.3V TO 3.5V 1H ATTENOUT SW2 40A ATTENIN BG2 V INTV DIFFOUT CC 10F C + OUT + V SENSE2 OS 1000F + 4V V SENSE2 OS 2 17097 F01 Figure 1. High Current 2-Phase Step-Down Converter 1 + S S U ULTC1709-8/LTC1709-9 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 NUMBER RUNN/SS 1 36 NC Topside Driver Voltages (BOOST1,2).........42V to 0.3V + SENSE1 2 35 TG1 Switch Voltage (SW1, 2) ..............................36V to 5V LTC1709EG-8 + + SENSE1 3 34 SW1 SENSE1 , SENSE2 , SENSE1 , LTC1709EG-9 EAIN 4 33 BOOST1 SENSE2 Voltages ........................ (1.1)INTV to 0.3V CC PLLFLTR 5 32 V IN + EAIN, V , V , EXTV , INTV , RUN/SS, OS OS CC CC PLLIN 6 31 BG1 V , ATTENIN, ATTENOUT, PGOOD, BIAS NC 7 30 EXTV CC VID0VID4, Voltages ...................................7V to 0.3V I 8 29 INTV CC TH Boosted Driver Voltage (BOOST-SW) ..........7V to 0.3V SGND 9 28 PGND PLLFLTR, PLLIN, V Voltages .... INTV to 0.3V DIFFOUT CC V 10 27 BG2 DIFFOUT I Voltage ................................................2.7V to 0.3V TH V 11 26 BOOST2 OS Peak Output Current <1m s(TGL1,2, BG1,2)................ 3A V + 12 25 SW2 OS INTV RMS Output Current................................ 50mA SENSE2 13 24 TG2 CC + SENSE2 14 23 PGOOD Operating Ambient Temperature Range ATTENOUT 15 22 V BIAS (Note 2) ................................................ 40 C to 85 C ATTENIN 16 21 VID4 Junction Temperature (Note 3)............................. 125 C VID0 17 20 VID3 Storage Temperature Range ................. 65 C to 150 C VID1 18 19 VID2 Lead Temperature (Soldering, 10 sec).................. 300 C G PACKAGE 36-LEAD PLASTIC SSOP T = 125 C, q = 90 C/W JMAX JA Consult factory for Industrial and Military grade parts. 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 (Note 4) l 0.792 0.800 0.808 V EAIN TH V Maximum Current Sense Threshold V = 5V l 62 75 88 mV SENSEMAX SENSE 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 Output Overvoltage Threshold Measured at V l 0.84 0.86 0.88 V OVL EAIN UVLO Undervoltage Lockout V Ramping Down 3 3.5 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 xZ No Ext Load) (Note 4) 1.5 V/mV mOL TH m L I Input DC Supply Current (Note 5) Q Normal Mode EXTV Tied to V , V = 5V 470 m A CC OUT OUT Shutdown V = 0V 20 40 m A RUN/SS I Soft-Start Charge Current V = 1.9V 0.5 1.2 m A RUN/SS RUN/SS V RUN/SS Pin ON Arming V Rising 1.0 1.5 1.9 V RUN/SS RUN/SS 2 U WWW