Buck PWM Controller

www.DataSheet4U.com 19-0546; Rev 0; 5/06 12V/5V Input Buck PWM Controller General Description The MAX5951 is a 12V pulse-width modulated (PWM), step-down, DC-DC controller. The device operates over the input-voltage range of 8V to 16V or 5V ±10%, and provides an adjustable output from 0.8V to 5.5V. The device delivers up to 10A of load current with excellent load-and-line regulation. The MAX5951 PWM section utilizes a voltage-mode control scheme for good noise immunity and offers external compensation, allowing for maximum flexibility with a wide selection of inductor values and capacitor types. The device operates at a fixed switching frequency that is programmable from 100kHz to 1MHz and can be synchronized to an external clock signal though the SYNCIN input. The device includes undervoltage lockout (UVLO) and digital soft-start. Protection features include lossless valley-mode current limit, hiccup-mode output short-circuit protection, and thermal shutdown. The MAX5951 is available in a space-saving 5mm x 5mm, 32-pin thin QFN package and is specified for operation over the -40°C to +85°C extended temperature range. Refer to the MAX5950 data sheet for a pincompatible PWM controller with hot swap. Features ♦ 8V to 16V or 5V ±10% Input-Voltage Range ♦ Lossless Valley-Mode Current Sensing ♦ Output Voltage Adjustable from 0.8V to 5.5V ♦ Voltage-Mode Control ♦ External Compensation for Maximum Flexibility ♦ Digital Soft-Start ♦ Sequencing or Ratiometric Tracking ♦ Startup Synchronization ♦ Programmable PGOOD Output ♦ Programmable Switching Frequency from 100kHz to 1MHz ♦ External Frequency Synchronization ♦ SYNCIN and SYNCOUT Enable 180° Out-of-Phase Operation ♦ Thermal Shutdown and Short-Circuit Protection ♦ Space-Saving, 5mm x 5mm, 32-Pin TQFN Package MAX5951 Ordering Information PART MAX5951ETJ+ TEMP RANGE -40°C to +85°C PINPACKAGE 32 TQFN PKG CODE T3255-4 Applications PCI-e Express Modules™ General 12V or 5V Input PWM Controllers Blade Servers RAID Base Stations Workstations +Denotes lead-free package. Pin Configuration ILIM CS+ TOP VIEW STARTUP 18 PGOOD SENSE COMP 24 CS- 25 PGND 26 DL 27 DREG 28 LX 29 DH 30 BST 31 REG 32 23 22 21 FB 20 19 17 16 15 14 13 SYNCIN SYNCOUT AGND THRESH DCENI N.C. N.C. N.C. MAX5951 RT 12 11 10 9 8 N.C. + 1 IN 2 PUVLO 3 N.C. 4 N.C. 5 IN 6 N.C. 7 N.C. PCI-e Express Modules is a trademark of PCI-SIG. TQFN (5mm x 5mm) ________________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 12V/5V Input Buck PWM Controller MAX5951 ABSOLUTE MAXIMUM RATINGS IN to AGND.............................................................-0.3V to +24V BST to AGND..........................................................-0.3V to +30V BST to LX..................................................................-0.3V to +6V CS- to AGND ...............................................-0.3V to (VIN + 0.3V) REG, DREG, PUVLO, DCENI, SYNCIN, THRESH, SENSE to AGND....................................................-0.3V to +6V RT, ILIM, STARTUP, PGOOD, FB, CS+ to AGND ....-0.3V to +6V SYNCOUT, COMP to AGND.....................-0.3V to (VREG + 0.3V) DL to PGND...............................................-0.3V to (VDREG + 6V) DH to LX ....................................................-0.3V to (VBST + 0.3V) PGND to AGND .....................................................-0.3V to +0.3V Input Current (any pin) .....................................................±50mA Continuous Power Dissipation (TA = +70°C) 32-Pin TQFN (derate 34.5 mW/°C above +70°C) .2758.6mW 32-Pin TQFN (θJA) ....................................................+29°C/W 32-Pin TQFN (θJC) ...................................................+2.1°C/W Operating Ambient Temperature Range .............-40°C to +85°C Maximum Junction Temperature .....................................+150°C Storage Temperature Range .............................-60°C to +150°C Lead Temperature (soldering, 10s) ......…………………..+300°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VIN = 12V or VIN = VREG = 5V, VDREG = VREG, VPGND = 0V, VSYNCIN = 0V, RRT = 100kΩ, RILIM = 60kΩ, CREG = 2.2µF, TA = TJ = -40°C to +85°C, unless otherwise noted. Typical values are at TA = TJ = +25°C.) (Note 1) PARAMETER Input-Voltage Range Standby Supply Current Quiescent Supply Current Switching Supply Current PWM UVLO Default PWM Undervoltage Lockout Threshold PWM Undervoltage Lockout Hysteresis PUVLO Threshold PUVLO Hysteresis PUVLO Input Impedance PWM DCENI CONTROL DCENI Comparator Input Common-Mode Range DCENI Comparator Offset DCENI Comparator Hysteresis DCENI Input Current THRESH Operating Voltage Range THRESH Input Current Default DCENI Threshold VTHRESH > 0.6V VTHRESH < 0.3V VTHRESH < 0.3V -1 0.6 -1.5 -5 1.202 1.22 VDCENI - VTHRESH 0 -10 100 +1 2.5 +1 +1 1.238 3 +10 V mV mV µA V µA V 180 VPUVLO VPUVLO rising 1.202 VIN rising 6.7 0.7 1.220 122 310 500 1.238 7.3 V V V mV kΩ SYMBOL VIN CONDITIONS VIN = VREG = VDREG (Note 2) VIN = 16V, VPUVLO = 0V VIN = 16V, VFB = 0.9V VIN = 16V, VFB = 0V MIN 8 4.5 0.3 1.6 5.0 TYP MAX 16 5.5 0.5 2.6 8.0 UNITS V mA mA mA 2 _______________________________________________________________________________________ 12V/5V Input Buck PWM Controller ELECTRICAL CHARACTERISTICS (continued) (VIN = 12V or VIN = VREG = 5V, VDREG = VREG, VPGND = 0V, VSYNCIN = 0V, RRT = 100kΩ, RILIM = 60kΩ, CREG = 2.2µF, TA = TJ = -40°C to +85°C, unless otherwise noted. Typical values are at TA = TJ = +25°C.) (Note 1) PARAMETER PWM PGOOD OUTPUT SENSE Threshold SENSE Hysteresis SENSE Input Bias Current PGOOD Internal Pullup Current PGOOD Output Voltage Low INTERNAL VOLTAGE REGULATOR Output Voltage Set Point Line Regulation Load Regulation PWM OSCILLATOR Oscillator Frequency Range fSW VSYNCIN = 0V, fSW = 5 x 1010 / RRT Hz TA = TJ = +25°C Oscillator Accuracy TA = TJ = -40°C to +85°C RT Voltage Maximum Duty Cycle SYNCIN High-Level Voltage SYNCIN Low-Level Voltage SYNCIN Pulldown Resistor SYNCIN Rising to SYNCOUT Falling Delay SYNCIN Falling to SYNCOUT Rising Delay Maximum SYNCIN Frequency SYNCOUT Voltage High SYNCOUT Voltage Low PWM ERROR AMPLIFIER FB Input Range FB Input Current COMP Output Voltage Range Open-Loop Gain Unity-Gain Bandwidth Reference Voltage fGBW VREF ICOMP = -500µA to +500µA 792 ICOMP = -500µA to +500µA 0 -250 0.25 80 2.5 800 808 VREF +250 VREG 0.5 V nA V dB MHz mV VHSYNCOUT ISYNCOUT = +1.2mA VLSYNCOUT ISYNCOUT = -2.4mA 1 VREG 0.1 50 50 100 10 30 VRT 50kΩ < RRT < 500kΩ VSYNCIN = 0V, VIN = 12V 82 2.1 0.8 150 fSW < 500kHz fSW > 500kHz fSW < 500kHz fSW > 500kHz 100 -2.5 -4 -3.5 -5 2 88 1000 +2.5 +4 +3.5 +5 kHz % % V % V V kΩ ns ns MHz V mV VREG VIN = 8V to 16V IREG = 0 to 50mA 4.7 5.3 1 150 V mV/V mV IPGOOD = -2.4mA -1 10 50 VSENSE rising 788 800 100 +1 812 mV mV µA µA mV SYMBOL CONDITIONS MIN TYP MAX UNITS MAX5951 _______________________________________________________________________________________ 3 12V/5V Input Buck PWM Controller MAX5951 ELECTRICAL CHARACTERISTICS (continued) (VIN = 12V or VIN = VREG = 5V, VDREG = VREG, VPGND = 0V, VSYNCIN = 0V, RRT = 100kΩ, RILIM = 60kΩ, CREG = 2.2µF, TA = TJ = -40°C to +85°C, unless otherwise noted. Typical values are at TA = TJ = +25°C.) (Note 1) PARAMETER PWM COMPARATOR Comparator Offset Voltage Comparator Propagation Delay PWM DIGITAL SOFT-START Soft-Start Duration Reference Voltage Steps PWM RAMP GENERATOR Ramp Amplitude PWM CURRENT-LIMIT COMPARATOR AND HICCUP MODE Cycle-by-Cycle Valley CurrentLimit Threshold Adjustment Range Cycle-by-Cycle Valley CurrentLimit Threshold Tolerance ILIM Reference Current ILIM Reference Current Tempco CS+, CS- Input Bias Current PWM HICCUP MODE Number of Cumulative CurrentLimit Events to Hiccup Number of Consecutive Noncurrent-Limit Cycles to Clear NCL Hiccup Timeout PWM STARTUP INPUT STARTUP Threshold STARTUP Threshold Hysteresis Internal Pullup Current STARTUP Output Voltage Low PWM DH DRIVER Peak Source Current Peak Sink Current DH Resistance Sourcing DH Resistance Sinking VDH,LX = 0V, pulse width < 100ns, VBST,LX = 5V VDH,LX = 5V, pulse width < 100ns, VBST,LX = 5V IDH = 50mA, VBST,LX = 5V IDH = -50mA, VBST,LX = 5V 2 2 1 1 3 3 A A Ω Ω ISTART ISTARTUP = -2.4mA VSUT 1.1 250 10 0.1 1.9 V mV µA V NCL 8 Clocks VCS+ = 0V, VCS- = -0.3V, current out of the CS_ -1 Limit = VILIM / 10 VILIM = 0.5V VILIM = 3.5V VILIM = 0 to 3.5V, TA = TJ = +25°C 50 44.5 330 19 20 3333 +20 350 55.5 366 21 mV 1.8 V 1024 128 6.3 Clocks Steps mV 0.3 40 V ns SYMBOL CONDITIONS MIN TYP MAX UNITS mV µA ppm/°C µA NCLR NHT 3 512 Clocks Clocks 4 _______________________________________________________________________________________ 12V/5V Input Buck PWM Controller ELECTRICAL CHARACTERISTICS (continued) (VIN = 12V or VIN = VREG = 5V, VDREG = VREG, VPGND = 0V, VSYNCIN = 0V, RRT = 100kΩ, RILIM = 60kΩ, CREG = 2.2µF, TA = TJ = -40°C to +85°C, unless otherwise noted. Typical values are at TA = TJ = +25°C.) (Note 1) PARAMETER PWM DL DRIVER Peak Source Current Peak Sink Current DL Resistance Sourcing DL Resistance Sinking Break-Before-Make Time THERMAL SHUTDOWN Thermal Shutdown Temperature Thermal Shutdown Hysteresis TJ rising 135 15 °C °C VDL = 0V, pulse width < 100ns, VDREG = 5V VDL = 5V, pulse width < 100ns, VDREG = 5V IDL = 50mA, VDREG = 5V IDL = -50mA, VDREG = 5V 2 2 1 1 25 3 3 A A Ω Ω ns SYMBOL CONDITIONS MIN TYP MAX UNITS MA