Synchronous Buck Controller

FAN5033 — 8-Bit Programmable 2- to 3-Phase Synchronous Buck Controller January 2007 FAN5033 8-Bit Programmable, 2- to 3-Phase, Synchronous Buck Controller Features Selectable 2- or 3-phase operation at up to 1MHz 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 with the Intel® VR10 and VR11 specifications Description The FAN5033 device is a multi-phase buck switching regulator controller optimized to convert a 12V input supply to the processor core voltage required by high ® performance Intel processors. It has an internal 8-bit 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 PWM signals to external MOSFET drivers that drive the switching power MOSFETs. The switching frequency of the design is programmable by a single resistor value. The number of phases can be programmed to support two- or three-phase applications. The FAN5033 also includes programmable no-load offset and droop functions to adjust the output voltage Selectable VR10 extended (7-bit) and VR11 (8-bit) www.DataSheet4U.com as a function of the load current, as required by the Intel VID tables specifications. The FAN5033 provides an accurate and Programmable soft-start ramp reliable short-circuit protection function with an adjustable over-current set point. Programmable short-circuit protection and latch-off delay The FAN5033 is specified over the commercial temperature range of 0°C to +85°C and is available in a Applications 32-lead MLP package. Desktop PC/Server processor power supplies for existing and next-generation Intel processors VRM modules Ordering Information Part Number FAN5033MPX Temperature Range 0°C to 85°C Pb-Free Yes Package Type MLP-32 Packing Method Tape and Reel Quantity 3,000 per Reel Intel is a registered trademark of Intel Corporation. ® © 2007 Fairchild Semiconductor 2006 FAN5033 Rev. 1.0.0 www.fairchildsemi.com FAN5033 — 8-Bit Programmable 2- to 3-Phase Synchronous Buck Controller Block Diagram VCC RT RAM PADJ FAN5033 UVLO SHUTDOWN & BIAS GND OSCILL ATOR SET EN RESE T PWM1 OD + – CMP Threshold EN – + + CURREN T BALANCING CIRCUI T – + – + – CMP RESE T PWM2 DAC+OV P CSREF CMP RESE T PWM3 + DAC - UV P 2 / 3 - PHASE DRIVER LOGIC – PWRGD DEL AY CROWBAR CURREN T LIMIT SW1 SW2 SW3 NC CSCOM P ILIMI T DEL AY CURREN T LIMIT CIRCUI T + – CSREF CSSUM Z + COM P – PRECISION REFERENCE FBRTN START-UP CONTRO L + – – FB + Boot Control VID DAC VIDSE L DAC BUFF SS VID7 VID6 VID5 VID4 VID3 VID2 VID1 VID0 Figure 1: Block Diagram © 2007 Fairchild Semiconductor 2006 FAN5033 Rev. 1.0.0 www.fairchildsemi.com 2 of 39 FAN5033 — 8-Bit Programmable 2- to 3-Phase Synchronous Buck Controller Pin Assignment Figure 2: Pin Assignment Pin Definitions Pin # 1 2 3 4 5 6 7 8 9 10 11 12 13 Name EN PWRGD FBRTN FB COMP SS DELAY ILIMIT RT RAMPADJ CSREF CSSUM CSCOMP 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-up 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. 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. 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. © 2006 Fairchild Semiconductor 2006 FAN5033 Rev. 1.0.0 www.fairchildsemi.com 3 of 39 FAN5033 — 8-Bit Programmable 2- to 3-Phase Synchronous Buck Controller Pin # 14 15 16 17 to 19 Name GND OD NC SW3 to SW1 PWM3 to PWM1 VCC VID7 to VID0 VIDSEL Exposed Paddle Description 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. (Also referred to as OD# in the text of this document.) No Connection. This pin is not connected internally. Switching Node Current Balance Inputs. Sense the switching side of the inductor and used to measure the current level in each phase. The SW pins of unused phases should be left open. PWM Outputs. Each output is connected to the input of an external MOSFET driver, such as the FAN5109. Connecting the PWM3 output to VCC disables that phase, allowing the FAN5033 to operate as a two-phase controller. Supply Voltage for the Device. Voltage Identification Code Inputs. These digital inputs are connected to the internal DAC and used to program the output voltage. These pins have 1µA internal pull-down; so if they are 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; so if left open, the input state is decoded as logic low. Internally connected to die ground. May be connected to ground or left floating. Connect to ground for lowest package thermal resistance. 20 to 22 23 24 to 31 32 - © 2006 Fairchild Semiconductor 2006 FAN5033 Rev. 1.0.0 www.fairchildsemi.com 4 of 39 FAN5033 — 8-Bit Programmable 2- to 3-Phase Synchronous Buck Controller Absolute Maximum Rating Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only. Unless otherwise specified, all other voltages are referenced to GND. Symbol VCC Supply Voltage FBRTN RAMPADJ, PWM3 SW1 – SW3 Parameter Min. -0.3 -0.3 -0.3 -10 -0.3 0 -65 Typ. Max. +15 +0.3 VCC + 0.3 +25 +5.5 +125 +150 300 260 45 Unit V V V V V °C °C °C °C °C/W All Other Inputs and Outputs TJ TSTG TL TLI θJA Operating Junction Temperature Storage Temperature Lead Soldering Temperature (10 seconds) Lead Infrared Temperature (15 seconds) Thermal Resistance Junction-to-Ambient (1) Note: 1. Junction-to-ambient thermal resistance, θJA, is a strong function of PCB material, board thickness, thickness and number of copper planes, number of via used, diameter of via used, available copper surface, and attached heat sink characteristics. Recommended Operating Conditions The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not recommend exceeding them or designing to absolute maximum ratings. Symbol VCC TA Ambient Temperature Parameter Supply Voltage, VCC to GND Min. 9.6 0 Typ. 12 Max. 14.4 +85 Unit V °C © 2006 Fairchild Semiconductor 2006 FAN5033 Rev. 1.0.0 www.fairchildsemi.com 5 of 39 FAN5033 — 8-Bit Programmable 2- to 3-Phase Synchronous Buck Controller Electrical Characteristics VCC = 12V, FBRTN = GND, and TA = +25°C. The • denotes specifications that apply over the full operating temperature range. Symbol Error Amplifier VCOMP Parameter Output Voltage Range Accuracy Relative to nominal DAC output, referenced to FBRTN. Figure 3 Accuracy Relative to nominal DAC output, referenced to FBRTN. Figure 3 Load Line Droop Accuracy Differential Non-linearity Conditions • VRM11 VID Range: 1.00625V to 1.60000V • Min. 0.5 Typ. Max. 4.0 Unit V VFB -7.7 +7.7 mV VFB(BOOT) During Start-up • 1.092 1.100 1.108 V CSREF-CSCOMP= 80mV Figure 5 VCC =10V to 14V • • • • -78 -1 -80 -82 +1 mV LSB % µA µA µA MHz V/µs ΔVFB IFB IFBRTN IO(ERR) GBW(ERR) VCSCOMP tBOOT VIH(VID) VIL(VID) VIH(VID) IIN(VID) Line Regulation Input Bias Current FBRTN Current Output Current Gain Bandwidth Product Slew Rate CSCOMP Voltage Range BOOT Voltage Hold Time Input Low Voltage Input High Voltage Select VR10 Table Select VR11 Table Input Current, VID Low VID Transition Delay Time No CPU Detection Turn-off Delay Time 0.05 13.5 15.0 70 500 20 25 • -250 2 • • 0.8 0.8 -1 0.4 3.3 0.4 3.3 16.5 95 FB forced to VOUT -3% COMP = FB (2) COMP = FB(2) Relative to CSREF CDELAY = 10nF VIDx, VIDSEL VIDx, VIDSEL VIDSEL Logic Low VIDSEL Logic High VID code change to FB change(2) VID code change to OFF state to PWM going low(2) +250 mV ms V V V V µA ns ns VID Inputs and VIDSEL • • 200 200 Oscillator fOSC fPHASE VRT VRAMPADJ IRAMPADJ Frequency Frequency Variation Output Voltage RAMPADJ Output Voltage RAMPADJ Input Current Range TA =