LM2720 February 3, 2000 5-Bit Programmable, High Frequency Multi-phase PWM Controller General Description The LM2720 provides an attractive solution for power supplies of high power microprocessors exhibiting ultra fast load transients. Compared to a conventional single-phase supply, an LM2720 based multi-phase supply distributes the thermal and electrical loading among components in multiple phases and greatly reduces the corresponding stress in each component. The LM2720 can be programmed to control either a 3-phase converter or a 4-phase converter. Phase shift among the phases is 120° in the case of three phase and 90° with four-phase. Because the power channels are out of phase, there can be significant ripple cancellation for both the input and output current, resulting in reduced input and output capacitor size. Due to the nominal operating frequency of 2 MHz per phase, the size of the output inductors can be greatly reduced which results in a much faster load transient response and a dramatically shrunk output capacitor bank. Microprocessor power supplies with all surface mount components can be easily built. The internal high speed transconductance amplifier guarantees good dynamic performance. The internal master clock frequency of up to 8 MHz is set by an external reference resistor. An external clock of 10 MHz can also be used to drive the chip to achieve frequency control and multi-chip operation. The LM2720 also provides input under-voltage lock-out with hysteresis, input over-current protection and output voltage power good detection. Features ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Ultra fast load transient response Enables all surface-mount-design Selectable 2, 3, 4 phase operation Clock frequency from 40 kHz to 10 MHz Precision load current sharing 5-bit programmable from 3.5V to 1.3V VID code compatible to VRM 8.X specification Output voltage is 2.0V for VID code 11111 Selectable internal or external clock Digital 16-step soft start Input under-voltage lock-out, over-current protection Open-drain power good signal output Applications ■ Servers and workstations ■ High current, ultra-fast transient microprocessors Pin Configuration 24-Pin Plastic SOIC 10132201 Top View See NS Package Number M24B © 2009 National Semiconductor Corporation 101322 101322 Version 3 Revision 1 www.national.com Print Date/Time: 2009/03/26 20:37:33 LM2720 5-Bit Programmable, High Frequency Multi-phase PWM Controller OBSOLETE LM2720 Storage Temperature ESD Susceptibility (Note 8) Soldering Time, Temperature Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. VCC5V PWRGD VCC12V Junction Temperature Power Dissipation (Note 2) −65°C to +150°C 2 kV 10 sec., 300°C Operating Ratings 7V (VCC 5V + 0.2V) 20V 125°C 1.6W (Note 1) VCC 5V VCC 12V Junction Temperature Range 4.5V to 5.5V 10V to 18V 0°C to 70°C Electrical Characteristics VCC5V = 5V, VCC12V = 12V unless otherwise specified. Typicals and limits appearing in plain type apply for TA = TJ = +25°C. Limits appearing in boldface type apply over the entire operating temperature range. Symbol Parameter Conditions VDACOUT 5-bit DAC Output Voltage (Note 3) ICC12V Quiescent VCC12V Current Enable = 5V, VID = 00001, DRV Outputs Floating ICC5V Operating VCC5V Current VOUT = 2.00V VREF Rref Pin Voltage VINL Vid0:4, Clksel, Divsel, and Enable Logic Low (Note 4) Pins Logic Threshold Logic High (Note 5) VINH Typ Max Units N N+1.5% V 1 2 mA 4.3 8 mA 1.225 Vid0:4 and Enable Pins Internal Pullup Current IINL Min N−1.5% Clksel, Divsel Pins Internal Pullup Current The Corresponding Pin = 0V 1.8 V 1.5 3.5 2.8 60 100 140 −10 0 10 V V µA 12 Ω VCC12V − 1.5V VCC12V −1.0V V 7 ns DRV0:3 = 0V, VCC12V = 14V 40 60 mA DRV0:3 Sink Current DRV0:3 = 5V, VCC12V = 14V 90 160 BgOUT Voltage Current Limit Not Activated 4 Current Limit Activated 0 Gate Driver Resistance When Sinking Current ISINK = 50 µA, VCC12V = 14V VDRV DRV0:3 Output Voltage IDRV = 10 mA, VCC12V = 14V tfall DRV0:3 Fall Time (Note 6) ISRC DRV0:3 Source Current ISINK VBgOUT V BgOUT Sink Current BgOUT = 1V IFB FB Pin Bias Current FB = 2V FOSC Oscillator Frequency 8.02kΩ from Rref Pin to Ground 7.0 8.7 MHz ΔD DRV0:3 Duty Cycle Match Duty Cycle = 50% −1 +1 % Δph DRV0:3 Phase Accuracy Duty Cycle = 50%, Fclock = 8 MHz −1 +1 Deg VPWRGD PWM Off time Power Good Detection Window, ΔVOUT 2.4 mA IBgOUT Toff 1.0 250 8.0 Divide by 4 22 Divide by 3 22 1.3V ≤ VOUT ≤ 1.9V www.national.com 2 101322 Version 3 Revision 1 5 30 Print Date/Time: 2009/03/26 20:37:33 ±100 mA nA % mV Parameter Conditions Min Hysteresis Typ Max Units 50 Power Good Detection Window, ΔVOUT 2V ≤ VOUT ≤ 3.5V ±150 Hysteresis 50 IPWRGD Power Good Sink Current VOCC_CM Over-current Comparator Common Mode Range IB_OC+ OC+ Input Bias Current VIN = 5V, OC+ = 5V, OC− = 4V 100 IB_OC− OC− Input Bias Current VIN = 5V, OC+ = 6V, OC− = 5V 85 VOS_OCC Over-current Comparator Input Offset Voltage VIN = 5V 2 DMAX Maximun Duty Cycle FB = 0V gm Error Amplifier Transconductance Vramp Ramp Signal Peak-to-Peak Amplitude Icomp COMP Pin Source Current 250 360 550 µA Icomp COMP Pin Sink Current 160 260 400 µA Vcomp_hi COMP Pin High Clamp 2.9 V Vcomp_lo COMP Pin Low Clamp 0.19 V VPOR Power On Reset Trip Point tSS VPWRGD = 0.4V 0.8 1 VIN = 12V mA 12 V 145 200 µA 120 165 µA 16 42 3 21 mV 78 % 1.36 mmho 2 V Vcc5V Pin Voltage Rising 4.0 Vcc5V Pin Voltage Falling 3.6 V Vcc12V Minimum Working Voltage (Note 7) 3.8 V Soft Start Delay 1.6 ms FOSC = 8MHz Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating ratings do not imply guaranteed performance limits. Note 2: Maximum allowable power dissipation is a function of the maximum junction temperature, TJMAX, the junction-to-ambient thermal resistance, θJA, and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated using: PMAX = (TJMAX − TA)/θJA. The junction-toambient thermal resistance, θJA, for LM2720 is 78°C/W. For a TJMAX of 150°C and TA of 25°C, the maximum allowable power dissipation is 1.6W. Note 3: The letter N stands for the typical output voltages appearing in italic boldface type in Table 1. Note 4: Max value of logic low means any voltage below this value is guaranteed to be taken as logic low whereas a voltage higher than this value is not guaranteed to be taken as a logic low. Note 5: Min value of logic high means any voltage above this value is guaranteed to be taken as logic high whereas a voltage lower than this value is not guaranteed to be taken as a logic high. Note 6: When driving bipolar FET drivers in the typical application circuit. Note 7: When Vcc12V pin goes below this voltage, all DRV pins go to 0V. Note 8: ESD ratings is based on the human body model, 100pF discharged through 1.5kΩ. 3 101322 Version 3 Revision 1 Print Date/Time: 2009/03/26 20:37:33 www.national.com LM2720 Symbol LM2720 TABLE 1. 5-Bit DAC Output Voltage Table Symbol VDACOUT Parameter Conditions 5-Bit DAC Output Voltages for Different VID Codes www.national.com Typical Units VID4:0 = 01111 1.30 V VID4:0 = 01110 1.35 VID4:0 = 01101 1.40 VID4:0 = 01100 1.45 VID4:0 = 01011 1.50 VID4:0 = 01010 1.55 VID4:0 = 01001 1.60 VID4:0 = 01000 1.65 VID4:0 = 00111 1.70 VID4:0 = 00110 1.75 VID4:0 = 00101 1.80 VID4:0 = 00100 1.85 VID4:0 = 00011 1.90 VID4:0 = 00010 1.95 VID4:0 = 00001 2.00 VID4:0 = 00000 2.05 VID4:0 = 11111 2.0 VID4:0 = 11110 2.1 VID4:0 = 11101 2.2 VID4:0 = 11100 2.3 VID4:0 = 11011 2.4 VID4:0 = 11010 2.5 VID4:0 = 11001 2.6 VID4:0 = 11000 2.7 VID4:0 = 10111 2.8 VID4:0 = 10110 2.9 VID4:0 = 10101 3.0 VID4:0 = 10100 3.1 VID4:0 = 10011 3.2 VID4:0 = 10010 3.3 VID4:0 = 10001 3.4 VID4:0 = 10000 3.5 4 101322 Version 3 Revision 1 Print Date/Time: 2009/03/26 20:37:33 LM2720 Pin Description Pin Pin Name Pin Function 1 Vcc5V Supply Voltage Input (5V nominal) 2 Divsel Selects Phase Mode. Logic low selects 4 phase. Logic high selects 3 phase. 2 phase operation is achieved by using 2 outputs in 4 phase mode. 3 Clksel Clock Select: Logic high selects internal clock. Logic low selects external clock. 4 Extclk External Clock Input. Output frequency = Clock Input / No. of Phases. Connect to Vcc5V to select internal clock. 5 Rref Connects to external reference resistor. Sets the operating frequency of the internal clock and the ramp time for the PWM. Reference voltage at this pin is 1.26V. 6 Vid0 5-Bit DAC Input (LSB). 7 Vid1 5-Bit DAC Input. 8 Vid2 5-Bit DAC Input. 9 Vid3 5-Bit DAC Input. 10 Vid4 5-Bit DAC Input (MSB) 11 OC+ Over-current Comparator. Non-inverting input. 12 OC− Over-current Comparator. Inverting input. 13 COMP Compensation Pin. This is the output of the internal transconductance amplifier. Compensation network should be connected between this pin and feedback ground FBG. 14 FB Feedback Input. Normally Kelvin connected to supply output. 15 Bgout Current Limit Flag. Goes to logic low when current limit is activated. When over-current condition is removed, this pin is weakly pulled up to Vcc5V. 16 FBG Feedback Ground. This pin should be connected to the ground at the supply output. 17 ENABLE Output Enable Pin. Tie to logic high to enable and logic low to disable. 18 GND Power Ground Pin. 19 DRV2 Phase 2 Output. 20 DRV0 Phase 0 Output. 21 Vcc12V Supply Voltage for FET Drivers DRV0:3. 22 DRV1 Phase 1 Output. 23 DRV3 Phase 3 Output. 24 PWRGD Power Good. This is an open-drain output that goes low (low impedance to ground) when the output voltage travels out of the threshold window, and resume to open-drain state when VOUT recovers into the 50mV hysteresis window. The power good window threshold, i.e. ±100mV for 1.3V ≤ VOUT ≤ 1.9V or ±150mV for 2V ≤ VOUT ≤ 3.5V, is automatically set according to VID code. Connect a 1nF capacitor to ground to filter out the switching noise coupling from DRV3 to this pin. 5 101322 Version 3 Revision 1 Print Date/Time: 2009/03/26 20:37:33 www.national.com LM2720 Block Diagram 10132202 www.national.com 6 101322 Version 3 Revision 1 Print Date/Time: 2009/03/26 20:37:33 LM2720 FIGURE 1. 10132203 Typical Application 7 101322 Version 3 Revision 1 Print Date/Time: 2009/03/26 20:37:33 www.national.com LM2720 Physical Dimensions inches (millimeters) unless otherwise noted 24-Lead Small Outline Package Order Number LM2720M NS Package Number M24B www.national.com 8 101322 Version 3 Revision 1 Print Date/Time: 2009/03/26 20:37:33 LM2720 Notes 9 101322 Version 3 Revision 1 Print Date/Time: 2009/03/26 20:37:33 www.national.com LM2720 5-Bit Programmable, High Frequency Multi-phase PWM Controller Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Design Support Amplifiers www.national.com/amplifiers WEBENCH® Tools www.national.com/webench Audio www.national.com/audio App Notes www.national.com/appnotes Clock and Timing www.national.com/timing Reference Designs www.national.com/refdesigns Data Converters www.national.com/adc Samples www.national.com/samples Interface www.national.com/interface Eval Boards www.national.com/evalboards LVDS www.national.com/lvds Packaging www.national.com/packaging Power Management www.national.com/power Green Compliance www.national.com/quality/green Switching Regulators www.national.com/switchers Distributors www.national.com/contacts LDOs www.national.com/ldo Quality and Reliability www.national.com/quality LED Lighting www.national.com/led Feedback/Support www.national.com/feedback Voltage Reference www.national.com/vref Design Made Easy www.national.com/easy PowerWise® Solutions www.national.com/powerwise Solutions www.national.com/solutions Serial Digital Interface (SDI) www.national.com/sdi Mil/Aero www.national.com/milaero Temperature Sensors www.national.com/tempsensors SolarMagic™ www.national.com/solarmagic Wireless (PLL/VCO) www.national.com/wireless Analog University® www.national.com/AU THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. NATIONAL MAKES NO REPRESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY OR COMPLETENESS OF THE CONTENTS OF THIS PUBLICATION AND RESERVES THE RIGHT TO MAKE CHANGES TO SPECIFICATIONS AND PRODUCT DESCRIPTIONS AT ANY TIME WITHOUT NOTICE. NO LICENSE, WHETHER EXPRESS, IMPLIED, ARISING BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS DOCUMENT. TESTING AND OTHER QUALITY CONTROLS ARE USED TO THE EXTENT NATIONAL DEEMS NECESSARY TO SUPPORT NATIONAL’S PRODUCT WARRANTY. EXCEPT WHERE MANDATED BY GOVERNMENT REQUIREMENTS, TESTING OF ALL PARAMETERS OF EACH PRODUCT IS NOT NECESSARILY PERFORMED. NATIONAL ASSUMES NO LIABILITY FOR APPLICATIONS ASSISTANCE OR BUYER PRODUCT DESIGN. BUYERS ARE RESPONSIBLE FOR THEIR PRODUCTS AND APPLICATIONS USING NATIONAL COMPONENTS. PRIOR TO USING OR DISTRIBUTING ANY PRODUCTS THAT INCLUDE NATIONAL COMPONENTS, BUYERS SHOULD PROVIDE ADEQUATE DESIGN, TESTING AND OPERATING SAFEGUARDS. EXCEPT AS PROVIDED IN NATIONAL’S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, NATIONAL ASSUMES NO LIABILITY WHATSOEVER, AND NATIONAL DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY RELATING TO THE SALE AND/OR USE OF NATIONAL PRODUCTS INCLUDING LIABILITY OR WARRANTIES RELATING TO FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS PRIOR WRITTEN APPROVAL OF THE CHIEF EXECUTIVE OFFICER AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: Life support devices or systems are devices which (a) are intended for surgical implant into the body, or (b) support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in a significant injury to the user. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system or to affect its safety or effectiveness. National Semiconductor and the National Semiconductor logo are registered trademarks of National Semiconductor Corporation. All other brand or product names may be trademarks or registered trademarks of their respective holders. Copyright© 2009 National Semiconductor Corporation For the most current product information visit us at www.national.com National Semiconductor Americas Technical Support Center Email: [email protected] www.national.com Tel: 1-800-272-9959 National Semiconductor Europe Technical Support Center Email: [email protected] 101322 Version 3 Revision 1 National Semiconductor Asia Pacific Technical Support Center Email: [email protected] Print Date/Time: 2009/03/26 20:37:33 National Semiconductor Japan Technical Support Center Email: [email protected]