LTC3738 3-Phase Buck Controller for Intel VRM9/VRM10 with Active Voltage Positioning FEATURES DESCRIPTIO 3-Phase Controller with Onboard MOSFET Drivers The LTC 3738 is a 3-phase synchronous step-down switch- Programmable Active Voltage Positioning (AVP) ing regulator controller that drives all N-channel external with True Current Sensing power MOSFET stages in a phase-lockable, fixed fre- Programmable External Thermal Detection or quency architecture. The 3-phase technique effectively Internal Thermal Sensing triples the fundamental frequency, improving transient Precise Output Current Matching Optimizes response while operating each controller at an optimal Thermal Performance and Solution Size frequency for efficiency and ease of thermal design. Light Supports Starting into Precharged V load efficiency is optimized by using a choice of output OUTS Differential Amplifier Accurately Senses V Stage Shedding or Pulse Skip mode technology. OUT TM PWM, Pulse Skip and Stage Shedding Operation The LTC3738 also allows users to program load slope via Synchronizable a resistor for AVP control. Both external and internal 210kHz to 530kHz Per Phase, Fixed Frequency thermal sensing are available from the on-chip thermal Output Power Good Indicator with Adaptive Blanking detector and comparator. Adjustable Soft-Start Current Ramping A differential amplifier provides sensing of both the high Short-Circuit Shutdown Timer with Defeat Option and low sides of the output voltage. OPTI-LOOP Compensation Minimizes C OUT 38-Lead (5mm 7mm) QFN Package Soft-start and a defeatable, timed short-circuit shutdown U protect the MOSFETs and the load. A foldback current APPLICATIO S circuit also provides protection for the external MOSFETs under short-circuit or overload conditions. An all- 1 VID High Performance Notebook Computers detector turns off the regulator after a 1s timeout. Servers, Desktop Computers and Workstations , LTC and LT are registered trademarks of Linear Technology Corporation. U.S. Patent Numbers: 5481178, 5994885, 5929620, 6177787, 6144194, 6580258, 6462525, OPTI-LOOP is a registered trademark of Linear Technology Corporation. 6593724, 6674274, 6100678 pending on AVP technique. Stage Shedding is a trademark of Linear Technology Corporation. TYPICAL APPLICATIO VRM10 Step-Down Controller V IN 5V TO 28V 5V V TG1 CC + 0.8H 0.002 22F LTC3738 10F SW1 2 BOOST1 BG1 BOOST2 BOOST3 + 0.1F SENSE1 SENSE1 SW3 SW2 SW1 V IN TG2 POWER GOOD INDICATOR PGOOD 0.8H 0.002 FCB/SYNC V MODE SELECTION/SYNC IN OUT SW2 0.8375V TO 1.6000V PLLFLTR BG2 THERMAL INPUT TSNS PGND VR HOTB VR HOT INDICATOR + ON/OFF OUTEN SENSE2 680pF SENSE2 V IN I TH TG3 0.8H 0.002 5k SS SW3 0.1F SGND BG3 EAIN AVP + SENSE3 100pF + SENSE3 470F + IN 4 VID0-VID5 6 VID BITS IN 3738 TA01 3738f 1 U ULTC3738 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) TOP VIEW Topside Driver Voltages (BOOST ) ............ 38V to 0.3V N Switch Voltage (SW )................................... 32V to 5V N Boosted Driver Voltage (BOOST SW ) .... 7V to 0.3V N N 38 37 36 35 34 33 32 Peak Output Current <1ms (TG , BG ) ..................... 5A N N FCB/SYNC 1 31 TG1 Supply Voltage (V ), PGOOD, VR HOTB PLLFLTR 2 30 SW1 CC IN 3 29 BOOST2 Pin Voltages ................................................ 7V to 0.3V + IN TG2 4 28 OUTEN, SS, PLLFLTR, AVP SW2 5 27 FCB/SYNC Voltages ................................... V to 0.3V CC EAIN 6 26 V CC 39 I Voltage ................................................ 2.4V to 0.3V TH + SENSE1 7 25 BG1 + IN , IN , VID0-VID5, TSNS .............................. 5V to 0V SENSE1 8 24 PGND + + AVP, SENSE , SENSE .................................. 1.9V to 0V SENSE2 9 23 BG2 SENSE2 22 BG3 Operating Ambient Temperature Range ....... 0C to 85C 10 SENSE3 11 21 SW3 Junction Temperature (Note 2)............................. 125C + SENSE3 12 20 TG3 Storage Temperature Range ..................65C to 125C 13 14 15 16 17 18 19 UHF PACKAGE 38-LEAD (7mm 5mm) PLASTIC QFN T = 125C, = 34C/W JMAX JA EXPOSED PAD (PIN 39) IS SGND MUST BE SOLDERED TO PCB ORDER PART UHF PART NUMBER MARKING LTC3738CUHF 3738 Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25C. V = V = V = 5V unless otherwise noted. A CC OUTEN SS SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Main Control Loop + V Regulated Voltage at IN (Note 3) VID Code = 110101, V = 1.2V 1.166 1.175 1.184 V REGULATED ITH 1.163 1.175 1.187 V V Maximum Current Sense Threshold V = 0.5V, V Open, 65 75 85 mV SENSEMAX EAIN ITH V V V = 0.8V, 1.85V 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, I Voltage = 1.2V to 0.7V 0.1 0.5 % TH Measured in Servo Loop, I Voltage = 1.2V to 2V 0.1 0.5 % TH V Output Voltage Line Regulation V = 4.5V to 7V 0.03 %/V REFLNREG CC g Transconductance Amplifier g I = 1.2V, Sink/Source 25A (Note 3) 3.05 mmho m m TH g Transconductance Amplifier GBW I = 1.2V, (g Z , Z = Series 1k-100k-1nF) 1.5 MHz mOL TH m L L V Forced Continuous Threshold 0.58 0.60 0.62 V FCB I FCB Bias Current V = 0.65V 0.2 0.7 A FCB FCB 3738f 2 SS OUTEN VID2 I TH TSNS VID1 VR HOTB VID0 VID3 VID5 VID4 PGOOD BOOST1 BOOST3 U WWW