National Semiconductor Application Note 2058 Mark Hartman November 2, 2010 General Description Features The LM10520 is a single-phase Energy Management Unit (EMU) that actively reduces system-level power consumption by utilizing a continuous, real-time, closed-loop Adaptive Voltage Scaling (AVS) scheme. The AVS technology enables optimum energy management delivery to the load in order to maximize system-level energy savings. The LM10520 evaluation board is capable of delivering up to 20A with an output voltage range of 0.6V - 1.2 V. It includes a DOSA compatible edge connector to enable convenient evaluation of AVS on a high performance ASIC or FPGA which typically require between 10A - 20A. Most of the features of the device can be accessed through jumper settings and the PWI interface. The LM10520 evaluation kit ships with 2 adaptor boards. The PWI2USB board allows connection to a PC for GUI control of the device. The AVS adaptor board stacks on top of the USB2PWI board and provides a header to connect to the LM10520. The AVS adaptor board also provides power connectors to conveniently apply high current loads and high voltage inputs that USB can not provide. • • • • • • • • • • Closed-loop/Adaptive Voltage Scaling (AVS) PWI 1.0/PWI 2.0 compatible Startup with a pre-biased output load Adjustable soft-start/tracking support PGOOD flag and shutdown Under Voltage Lock Out (UVLO) Over Voltage Protection (OVP) Ability to synchronize switching frequency Cycle-by-cycle current limiting Thermal Shutdown Applications • • • • • Point of Load regulation Servers and networking cards Set-top-box processors Video processors and graphic cards Medical and industrial processors Operation Range Parameter PVIN Min Max Units ∼5 14 V ∼3 A IPVIN AVIN* 4.75 5.25 V 100 mA IAVIN VOUT 0.72 1.2 V IOUT 0 20 A * AVIN improves efficiency, but is not required. LM10520 20A Adaptive Voltage Scaling (AVS) Evaluation Board LM10520 20A Adaptive Voltage Scaling (AVS) Evaluation Board AN-2058 © 2010 National Semiconductor Corporation 301238 www.national.com AN-2058 System Diagram 30123801 FIGURE 1. 20A Module System Connections www.national.com 2 AN-2058 Connections Dimensions are in inches Pin Diameter is 0.025 inches. 30123802 FIGURE 2. Board Dimensions 3 www.national.com AN-2058 Pin Descriptions Pin Parameter 1 VOUT AVS output voltage 2 VOUT AVS output voltage 3 SENSE 4 Vout 5 GND 6 GND Description AVS output voltage feedback. Route a separate (low current) trace from this pin to the point of load. AVS output voltage 7 GND 8 SCLK PWI clock 9 SPWI PWI data 10 VPWI PWI supply input 3.3V/ 2.5V/ 1.8V 11 AVIN Analog input voltage. 4.5V - 5.5V 12 PGOOD Power good signal output 13 I Share Not used 14 GND 15 VIN Power input voltage. 16 VIN Power input voltage. 17 SEQ Not used 18 TRIM Not used 19 ON/OFF www.national.com Drive this pin between 1.3V and AVIN to enable the output voltage. Pulling this pin to ground shuts down the output and the device. 4 AN-2058 Typical Performance Curves Efficiency (PVIN = 12V, AVIN = 4.5V, fs = 300 kHz Load Transient Response 100 EFFIICIENCY (%) 95 VOUT = 1.2V VOUT = 1.0V 90 85 80 VOUT = 0.9V VOUT = 0.8V 75 70 0 2 4 6 8 10 12 14 16 18 20 30123819 IOUT (A) 30123818 Switching Waveforms 30123820 5 www.national.com AN-2058 The AVS adaptor board provides several options for powering and loading the LM10520 evaluation board. Jumper settings for these configurations are described in table 1, and shown in a simplified schematic in Figure 3. The default configuration provides means for a simple evaluation of LM10520 requiring only a USB connection. However, because of the limited power output of USB, the LM10520 should not be loaded at its output for this configuration. For a wider range of input and output voltage/current, external power supplies and loads can be connected to the AVS adaptor via the banana jacks. See Table 1 for jumper settings to route power through the banana jacks. Startup Guide STANDALONE The LM10520 evaluation board can operate from a single bias at PVIN (5 - 14V). VOUT is enabled via the ON/OFF pin. It is recommended that this pin be actively driven high or low. CONNECTED TO PC/GUI The LM10520 evaluation board can be connected to a PC and controlled from a GUI by connecting it to the USB2PWI and AVS adaptor boards. The USB2PWI board provides 5V power and PWI communication, while the AVS adaptor board provides a 19-pin DOSA compliant header to connect the LM10520 board into. TABLE 1. AVS Adaptor Jumper Settings Jumper JP1 Description AVIN* JP2 PVIN JP3 Sense + JP4 JP5 Sense ON/OFF pullup Connection Configuration 1-2 AVIN connected to USB 5V 2-3 AVIN provided by LM10520 internal rail (if AVIN banana jack left floating), or AVIN provided externally (if power is provided to AVIN banana jack/DOSA connector) 1-2 PVIN connected to USB 5V 2-3 PVIN provided externally 1-2 Feedback signal taken from remote sense terminal 2-3 Feedback signal taken from local feedback trace. 1-2 Feedback ground taken from remote sense terminal. 2-3 Feedback ground taken from local trace. 1-2 LM10520 eval board ON/OFF pulled up to AVIN. 2-3 LM10520 eval board ON/OFF weak pull down to GND * JP1 only selects how AVIN power is routed to the DOSA receptacle J1. Jumper JP6 on the LM10520 eval board selects how power is routed to the AVIN pin of LM10520. TABLE 2. LM10520 Evaluation Board Jumper Settings Jumper JP4 JP6 JP7 JP8 JP9 JP10 www.national.com Connection Description 1-2 Connects FLT_N to PWGD 2-3 Connects FLT_N to GND 1-2 Connects AVIN to external input 2-3 Connects AVIN to VIN 1-2 Connects ENABLE_BIAS to VCC5 2-3 Connects ENABLE_BIAS to GND 1-2 Connects CONTROL to VDD 2-3 Connects CONTROL to external input 1-2 Connects RESET_N to VCC5 2-3 Connects RESET_N to GND 1-2 Connects ON/OFF to GND 2-3 Connects ON/OFF to ENABLE_BIAS 6 AN-2058 TABLE 3. LM10520 Input/Measurement Headers Header Description JP1 Connects VCC5 to PWGD LED indicator JP2 Tracking input for startup tracking JP3 Clock input for Sync function P1 DOSA compliant connector P2 Remote sense measurement. Pins 1-2 measure SENSE to GND. By default, GND is local GND. By removing R13 and connecting pin 3 of the header to the remote GND, pins 1-2 will measure SENSE to remote GND. See schematics. P3 PWI header P4 VOUT measurement P5 Switch node measurement 7 www.national.com AN-2058 30123806 FIGURE 3. Simplified Schematic of the Jumper Options on the LM10520 Evaluation and AVS Adaptor Boards www.national.com 8 ADJUSTING THE DEFAULT OUTPUT VOLTAGE The default output voltage of LM10520 is set by the feedback resistor divider ratio, RFB1 and RFB2. The default output voltage can be expressed as: The LM10520 demo board ships with RFB1 and RFB2 = 10 kΩ, which yields a 1.2V default output voltage. Resistor ratios for common default output voltages are shown in Table 4. TABLE 4. Default Output Voltages Default Output Voltage RFB1 RFB2 VPWI 1.0V 10K 15K 0.9V 10K 20K PWI is a push-pull interface, and thus the master and slave I/ O needs to drive to the same voltage. LM10520 has a VPWI input, which determines the high voltage for the PWI I/O. VPWI needs to be the same voltage as the I/O on the slave’s PWI clock and data pins. VPWI must be provided in order for the PWI interface to communicate. AVIN The AVIN pin can accept a 4.5 – 5.5V input, which is used to bias the analog circuitry of the LM10520. Slightly higher conversion efficiency (when using a 12V power input rail) can be achieved by providing AVIN. 9 www.national.com AN-2058 SENSE The SENSE pin (header P1, pin 3) provides the option for remote feedback connection, so that the LM10520 regulates VCORE as seen at the remote location. This has the benefit of regulating out the IR drops seen across the connector and traces. However, remote sensing is inherent in the AVS loop, and there is no benefit to connecting the SENSE pin when AVS is enabled. By default, the SENSE pin is connected to the three VAVS pins by a 0Ω resistor (R13) on the LM10520 evaluation board. To enable remote sensing, make R13 open, and ensure that the sense pin is connected to the VAVS rail on the motherboard. If the sense pin is not connected to VAVS, the LM10520 will have no feedback, and the output voltage could go as high as the VIN rail. Options AN-2058 PowerWise® Interface Address Selection A 1% resistor at R22 sets the PWI address. PWI Standard Description Min Typ 0 Max Unit RPWI1.0 Address selection resistor for PWI-1.0 20 kΩ RPWI2.0-0 Address selection resistor for PWI-2.0, address 0 40.2 kΩ RPWI2.0-1 Address selection resistor for PWI-2.0, address 1 60.4 kΩ RPWI2.0-2 Address selection resistor for PWI-2.0, address 2 80.6 kΩ RPWI2.0-3 Address selection resistor for PWI-2.0, address 3 100 kΩ RPWI2.0-4 Address selection resistor for PWI-2.0, address 4 120 kΩ RPWI2.0-5 Address selection resistor for PWI-2.0, address 5 140 kΩ RPWI2.0-6 Address selection resistor for PWI-2.0, address 6 160 kΩ RPWI2.0-7 Address selection resistor for PWI-2.0, address 7 180 8 kΩ Operating Ratings Thermal Considerations The LM10520 evaluation board can provide a 0.72 – 1.2V, 0 – 20A output. Its default voltage upon startup is 1.2V. Using PWI voltage commands, the output voltage can be changed. The LM10520 evaluation board has not been tested for thermal derating and air flow requirements. In general, the board temperature rise for a 12V single rail input to 1.2V output providing a 10A load with no air flow is about 40°C - 50°C. Therefore, for any load > 10A, it is recommended to place a fan near the board. www.national.com 10 AN-2058 Schematics 30123811 FIGURE 4. LM10520 Schematics: LM10520 and Low-Power Components 11 www.national.com AN-2058 30123812 FIGURE 5. LM10520 Schematics: Power Stage www.national.com 12 AN-2058 LM10520 Evaluation Board Bill of Materials Designator Comment Footprint Manufacturer C1 ECJ-2VB1H153K 0805 Panasonic C2 TMK107BJ474KA-T 0603 Taiyo Yuden C3 C1608C0G1H101J 0603 TDK C4, C9 GRM21BR71H105KA12L 0805 Murata C5 C1608X7R1H102K 0603 TDK C6 C1608C0G1H180J 0603 TDK C7 C3216X7R1H105K 1206 TDK C8 C3225X7R1H225K/2.50 1210 TDK C10, C11 C4532X7R1E226M 1812M TDK C12 UMK107B7104KA-T 0603 C13, C14 2R5TPE220M9 C15 GRM1885C1H182JA01D D1 LNJ311G83RA D2, D3, D4 MBR120LSFT1G D5 Vishay SL22-E3/52T L1 SER2010-202ML Q1 NDS331N SOT23A Fairchild Semiconductor Q2, Q3 IRF6633 IRF6722 Internation Rectifier Q5 IRF6609 IRF6609 Internation Rectifier R1, R2, R3, R4, R14, R16, R17, R18, R20, R23 CRCW08051K00FKEA 0805 Vishay R5 MCR03EZPJ000 805 Rohm Semiconductor R6 CRCW0805100KFKEA 0805 Vishay R7, R11, R26 CRCW080510R0FKEA 0805 Vishay R8 CRCW060320K0FKEA 0603 Vishay R9 RC0603FR-071K82L 0603 Yageo R10 CRCW060327R0FKEA 0603 Vishay R12 CRCW060340K2FKEA 603 Vishay R13, R15 CRCW06030000Z0EA 0603 Vishay R19 CRCW060310R0FKEA 0603 Vishay R21, R22, R24 NL 0603 R27, R33 CRCW060310K0FKEA 0603 Vishay R28, R29, R31, R32 CRCW060362R21FNEA 0603 Vishay R30 RL3264SW4-005M M-RES-LKV25 Vishay R34 CRCW0603280RFKEA 0603 Vishay Rfb1, Rfb2 CRCW080510K0FKEA 0805 Vishay U1 LM10520 Taiyo Yuden Taiyo Yuden 0603 Diode_1206 SOD-123 SMB IHLP6767 eTSSOP28 13 Murata Panasonic ON Semiconductor Vishay Coilcraft National Semiconductor www.national.com AN-2058 Layout Artwork 30123803 FIGURE 6. Top and Top Overlay 30123804 FIGURE 7. Bottom and Bottom Overlay www.national.com 14 AN-2058 30123813 FIGURE 8. Mid-Layer 1 30123814 FIGURE 9. Mid-Layer 2 15 www.national.com AN-2058 30123815 FIGURE 10. Mid-Layer 3 30123816 FIGURE 11. Mid-Layer 4 www.national.com 16 AN-2058 Notes 17 www.national.com LM10520 20A Adaptive Voltage Scaling (AVS) Evaluation Board Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com 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 References www.national.com/vref Design Made Easy www.national.com/easy www.national.com/powerwise Applications & Markets www.national.com/solutions Mil/Aero www.national.com/milaero PowerWise® Solutions Serial Digital Interface (SDI) www.national.com/sdi Temperature Sensors www.national.com/tempsensors SolarMagic™ www.national.com/solarmagic PLL/VCO www.national.com/wireless www.national.com/training PowerWise® Design University THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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