8-Bit Programmable 2 to 4 Phase Synchronous Buck Controller

FAN5032 8-Bit Programmable 2 to 4 Phase Synchronous Buck Controller April 2006 FAN5032 8-Bit Programmable 2 to 4 Phase Synchronous Buck Controller Features ■ Selectable 2, 3, or 4 phase operation at up to 1MHz ■ ■ ■ ■ ■ ■ ■ ■ Description The FAN5032 is a controller for a multi-phase buck switching regulator optimized to convert a 12V input supply to the processor core voltage required by highperformance Intel processors. It has an internal 8-bit digital to analog converter (DAC) that converts a digital voltage identification (VID) code, sent from the processor to set the output voltage between 0.5V and 1.6V in 6.25mV steps. It outputs a pulse-width modulated (PWM) signal to external MOSFET drivers that, in turn, drive the switching power MOSFETs. The switching frequency of the design is programmable by a single resistor value and the number of phases can be programmed to support 2, 3, or 4 phase applications. per phase ±7.7mV worst-case differential sensing error over temperature Active current balancing between the output phases Power good and crowbar blanking supports on-the-fly VID code changes 0.5V to 1.6V output Fully compliant to Intel® VR10 and VR11 specifications Selectable VR10 extended (7 bit) and VR11 (8 bit) VID tables Programmable soft-start ramp Programmable short-circuit protection and latch-off delay Special Features ■ 300mV OVP and crowbar threshold The FAN5032 also includes programmable no-load offset and droop functions to adjust the output voltage as a function of the load current, as required by the Intel specifications. The FAN5032 also provides an accurate and www.DataSheet4U.com reliable short-circuit protection function with an adjustable over-current set point. The FAN5032 is specified over the commercial temperature range of 0°C to 85°C and is available in a 40-lead MLP package. Applications ■ Desktop PC/server processor power supplies for existing and next-generation Intel processors ■ VRM modules Ordering Information Product Number FAN5032MPX Package Type MLP-40 Pb-Free Yes Operating Temperature Range 0°C to 85°C Packing Meathod Tape and Reel Quantity per Reel 3,000 ©2006 Fairchild Semiconductor Corporation 1 www.fairchildsemi.com FAN5032 Rev. 1.0.0 FAN5032 8-Bit Programmable 2 to 4 Phase Synchronous Buck Controller FAN5032 Block Diagram VCC 31 RT 12 RAMPADJ 13 UVLO SHUTDOWN & BIAS GND 18 OSCILLATOR SET EN RESET 19 OD + – CMP 30 PWM1 850mV – + + EN 1 CURRENT BALANCING CIRCUIT – + – CMP RESET 29 PWM2 + – DAC+150mV CSREF CMP RESET 28 PWM3 + + – CMP RESET 27 PWM4 DAC-250mV – 2 / 3 / 4-PHASE DRIVER LOGIC 26 NC PWRGD 2 DELAY CROWBAR CURRENT LIMIT 25 SW1 TTSENSE 10 VRHOT 9 VRFAN 8 THERMAL THROTTLING CONTROL 24 SW2 23 SW3 22 21 SW4 NC 17 CSCOMP CSREF CSSUM ILIMIT 11 DELAY 7 CURRENT LIMIT CIRCUIT + – 15 16 Z + 14 LLSET COMP 5 – – + – 4 PRECISION REFERENCE FBRTN 3 FB STARTUP CONTROL Boot Control + VIDSEL 40 32 33 34 VID DAC DAC BUFF 6 SS 35 36 37 38 39 VID7 VID6 VID5 VID4 VID3 VID2 VID1 VID0 Figure 1. Block Diagram 2 FAN5032 Rev. 1.0.0 www.fairchildsemi.com FAN5032 8-Bit Programmable 2 to 4 Phase Synchronous Buck Controller FAN5032 Pin Assignment PWM1 PWM2 PWM3 PWM4 SW1 SW2 SW3 SW4 22 NC 30 29 28 27 26 25 24 23 VCC VID7 VID6 VID5 VID4 VID3 VID2 VID1 VID0 VIDSEL 21 NC 31 32 33 34 35 36 37 38 39 40 10 1 2 3 4 5 6 7 8 9 20 NC OD GND CSCOMP CSSUM CSREF LLSET RAMPADJ RT ILIMIT Exposed paddle on bottom of package 19 18 17 16 15 14 13 12 11 (Top View) Figure 2. Pin Assignment Pin Assignments Pin # 1 Pin Name EN Pin Description Power Supply Enable Input. Analog comparator input with hysteresis. If input voltage is higher than the internal threshold, the controller is enabled. If lower, the controller is disabled. Power Good Output. Open drain output that pulls to GND when the output voltage is outside the proper operating range. Feedback Return. VID DAC and error amplifier reference for remote sensing of output voltage. Feedback Input. Error amplifier input for remote sensing of output voltage. A positive internal current source is connected to this pin to allow the output voltage to be offset lower than the DAC voltage. Error Amplifier Output. For loop compensation. Soft-Start Input. An external capacitor connected between this pin and GND sets the soft-start ramp time. Delay Timer Input. An external capacitor connected between this pin and GND sets the over-current latch-off delay time, BOOT voltage hold time, EN delay time, and PWRGD delay time. VR Fan Output. Open drain output that goes high when the TTSENSE voltage goes below the internal VRFAN threshold. 2 3 4 PWRGD FBRTN FB 5 6 7 COMP SS DELAY 8 VRFAN 3 FAN5032 Rev. 1.0.0 TTSENSE PWRGD FB FBRTN COMP SS VRHOT EN VRFAN DELAY www.fairchildsemi.com FAN5032 8-Bit Programmable 2 to 4 Phase Synchronous Buck Controller Pin Assignments (Continued) Pin # 9 10 Pin Name VRHOT TTSENSE Pin Description VR Hot Output. Open drain output that goes high when the TTSENSE voltage goes below the internal VRHOT threshold. Thermal Sense Input. A positive internal current source is connected to this pin. Connecting an external NTC thermistor between this pin and GND produces a positive input voltage that is proportional to temperature. Current Limit Set. An external resistor from this pin to GND sets the current limit threshold of the converter. Frequency Set Input. An external resistor connected between this pin and GND sets the oscillator frequency of the device. PWM Ramp Set Input. An external resistor connected between this pin and the converter input voltage sets the internal PWM ramp. Load Line Set Input. This pin can be directly connected to CSCOMP or connected to the center point of a resistor divider between CSCOMP and CSREF. Connecting LLSET to CSREF disables positioning. Current Sense Amplifier Positive Input. The voltage on this pin is used as the reference for the current sense amplifier. The power good and crowbar functions are also internally connected to this pin. Current Sense Amplifier Negative Input Current Sense Amplifier Compensation Output Ground. All internal biasing and logic output signals of the device are referenced to this ground. Output Disable. This pin is actively pulled low when the EN input is low or when VCC is below its UVLO threshold, to disable the external MOSFET drivers. No Connection Switching Node Current Balance Inputs. Sense the switching side of the inductor and are used to measure the current level in each phase. The SW pins of unused phases should be left open. No Connection 11 12 13 14 ILIMIT RT RAMPADJ LLSET 15 CSREF 16 17 18 19 CSSUM CSCOMP GND OD 20 to 21 NC 22 to 25 SW4 to SW1 26 NC 27 to 30 PWM4 to PWM1 PWM Outputs. Each output is connected to the input of an external MOSFET driver, such as the FAN5109. Connecting the PWM3 and/or PWM4 outputs to VCC disables that phase, allowing the FAN5032 to operate as a 2, 3, or 4 phase controller. 31 VCC Supply Voltage for the Device Voltage Identification Code Inputs. These digital inputs are connected to the internal DAC and are used to program the output voltage. These pins have 1µA internal pulldown; left open, the input state is decoded as logic low. VID Table Select Input. A logic low selects the extended VR10 DAC table and a logic high selects the VR11 DAC table. This pin has a 1µA internal pull-down; left open, the input state is decoded as logic low. 32 to 39 VID7 to VID0 40 VIDSEL – Exposed Paddle Internally connected to die ground. May be connected to ground or left floating. Connect to ground for lowest package thermal resistance. 4 FAN5032 Rev. 1.0.0 www.fairchildsemi.com FAN5032 8-Bit Programmable 2 to 4 Phase Synchronous Buck Controller Mechanical Dimensions 40-Lead MLP 5 FAN5032 Rev. 1.0.0 www.fairchildsemi.com FAN5032 8-Bit Programmable 2 to 4 Phase Synchronous Buck Controller TRADEMARKS The following are registered and unregistered trademarks Fairchild Semiconductor owns or is authorized to use and is not intended to be an exhaustive list of all such trademarks. ACEx™ FAST® ActiveArray™ FASTr™ Bottomless™ FPS™ Build it Now™ FRFET™ CoolFET™ GlobalOptoisolator™ CROSSVOLT™ GTO™ DOME™ HiSeC™ EcoSPARK™ I2C™ E2CMOS™ i-Lo™ EnSigna™ ImpliedDisconnect™ FACT™ IntelliMAX™ FACT Quiet Series™ Across the board. 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