ISL6327EVAL5: Voltage Regulator Coupled Inductor Solution using the ISL6327 and ISL6609 ® Application Note October 26, 2010 AN1268.0 Author: Jason Houston Introduction ISL6327EVAL5 VRD Reference Design Today’s microprocessors are continuing towards higher power consumption and functionality. Vcore regulators have the burden of increasing load demands coupled with tighter voltage regulation requirements. Power designers are challenged with the design of high performance regulators that can meet tight load regulation windows with increasing maximum load and transient requirements and falling output voltages. Add to that the push for higher efficiency solutions and decreasing PCB real estate; meeting today’s microprocessor power requirements is no simple task. The evaluation kit consists of the ISL6327EVAL5 evaluation board, the ISL6327 datasheet, and this application note. The evaluation board is designed to meet the output voltage and current specifications shown in Table 1, with the VID DIP switches, SW2, set to 00101010 (1.35V). Intersil ISL6327 With Coupled Inductors Load Line Slope To help meet these design challenges Intersil offers a complete reference design and evaluation package that takes advantage of the features of the ISL6327 controller and an output filter topology using coupled inductors and fewer output capacitors. Continuous Load Current 130A Load Current Step 100A The ISL6327 controls a microprocessor core voltage, balances channel currents, and provides protective features for up to 6 synchronous buck channels in parallel. The controller uses a 8-bit DAC giving the user a digital interface to select the output voltage, which is precisely regulated to ±0.5% accuracy using differential remote voltage sensing. The DAC can be set up to read VR10 or VR11 VID codes. Other features of the controller include overcurrent, overvoltage, and undervoltage protection, internal over temperature protection, programmable output voltage offset, dynamic VID circuitry, and an IOUT pin that provides a voltage proportional to the load current. To meet the extremely fast load transients of microprocessors the ISL6327 utilizes Intersil’s proprietary Active Pulse Positioning (APATM) and Adaptive Phase Alignment (APATM) modulation scheme and continuous current sensing to achieve extremely fast load transient response with fewer output capacitors. ‘Coupled’ with the fast control scheme a new approach to the output filter can be implement using coupled inductors. Coupling of two phases on one core allows the use of a small output inductance for fast transient response without taking the hit in efficiency due to higher individual phase peak-to-peak current for an equivalent standard inductance. The ISL6327 and ISL6609 datasheets along with the latest documentation can be found on our website: www.intersil.com. 1 TABLE 1. ISL6327EVAL5 DESIGN PARAMETERS PARAMETER MAX TYPICAL MIN No Load VCORE Regulation 1.35V 1.33V 1.31V VCORE Tolerance +20mV Load Current Transient -20mV 1.25mΩ 1200A/μs The board is configured for down conversion from 12V to the DAC setting. The evaluation board provides many test points, two types of power supply connectors, an on-board LGA775/771 socket for transient response evaluation and terminal connectors for DC load testing. An on-board LED is present to indicate the status of the PGOOD signal. The printed circuit board is implemented in 6-layer, 1-ounce copper. The layout and stackup are designed to emulate a real world CPU/VCORE implementation. The board schematic and BOM is provided at the end of the application note. Quick Start Evaluation The ISL6327EVAL5 is designed for quick start-up and evaluation. All that is required is a single ATX power supply. To begin evaluating the ISL6327EVAL5 follow the steps below. 1. Before doing anything to the evaluation board, make sure the “Enable” switch (EN1) is in the OFF position. 2. Using an ATX power supply, connect the 24-pin main power supply header to the “5V Power” connector (5V_PWR1) on the board. Next connect the 4-pin 12V header to the “12V Power” connector (12V_PWR1) on the board. 3. Set the “Static VID” DIP switch (SW2) to 00101010 (VID7:0 as printed on the silkscreen).Set SW1 to 0001. 4. Move the “Enable” switch (S1) to the ON position to begin regulation. After step 4, the ISL6327EVAL5 should be regulating the output voltage. The test points “TPVCORE1” and “TPGND1” can be used to monitor the output voltage initially to verify regulation. CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright © Intersil Americas Inc. 2010. All Rights Reserved All other trademarks mentioned are the property of their respective owners. Application Note 1268 ISL6327EVAL5 Board Features Input Power Connections The ISL6327EVAL5 includes two different methods for powering up the board. The first method allows for the use of an ATX power supply. The 24-pin header, 5V_PWR1, allows for the connection of the main ATX power connector, while the 4-pin header, 12V_PWR1, connects the 12V AUX power. It is very important that both connections are secure and the EN1 switch is in the OFF position before switching on the ATX supply. The second method of powering the ISL6327EVAL5 board is with bench power supplies. Four female banana jacks are provided for connecting bench-top supplies. A +5V, 1A and +12V, 20A supply will be needed for full evaluation. Connect the +5V terminal to the 5V1 jack and the +5V GND terminal to 5V_GND1. Connect the +12V terminal to 12V1 and the +12V GND terminal to 12V_GND1. Voltage sequencing is not required when powering the evaluation board. The VTT must also be powered with +5V and +12V at the 4-pin power input connector. Refer to your VTT users guide and software for details on exact test setup and software use. VID Setting The VID input on the ISL6327EVAL5 can be set by using the on board SW2 DIP switch. The switches are labeled VID7 to VID0. Or the VID can be controlled through the VTT software. To select which method controls the VID pins of the ISL6327 the jumpers J_VID7 to J_VID0 need to be placed accordingly. For VTT control of the VID, place the jumper hats on pins 1 and 2 of the 3-pin connector for J_VID7 - J_VID0. The 4th switch on SW1 should also be switched to VTT (labeled on the PCB silk-screen). To allow the DIP switches to control the VID move switch 4 of SW1 DIP switch to DEMO and move the jumper hats to pins 2 and 3 of J_VID7 to JVID_0. Once power is applied to the board, the PGOOD LED indicator will illuminate red. With EN1 in the OFF position, the ENABLE input of the ISL6327 is held low and the startup sequence is inhibited. The VID DIP switches should be preset to 00101010 (1.35V with 20mV offset). If another output voltage level is desired, refer to the ISL6327 datasheet for the complete DAC table and change the VID switches accordingly. Output DC Power Connections Both VR10 and VR11 VID codes can be used with the ISL6327EVAL5. To use VR11 move switch 1 of SW1 DIP switch towards VR11. To use VR10 move switch 1 of SW1 towards VR10. The ISL6327EVAL5 output can be exercised using a DC electronic load through the output terminal lugs labeled VCORE1 and GND1. Tie the positive load connection to VCORE1 and the negative load connection to GND1. A shielded scope probe test point, TP1, allows for inspection of the output voltage, VCORE. This probe is connected to VSENSE through 0Ω resistors on the back of the PCB labeled VTT_R1 and VTT_R2. LGA775/771 VTT Evaluation To fully exercise the regulation of the ISL6327EVAL5 a LGA775/771 VTT is needed. A LGA775/771 VTT socket is populated on the PCB. To ensure the ISL6327 regulates to the die sense location on the VTT, 0Ω resistors are populated on the back side of the PCB labeled R40 and R42. These must be populated for correct voltage measurements when using the VTT. After inserting the interposer and VTT in the LGA775/771 socket a differential voltage probe should be connected to the VCC-REG-N/VSS-REG-N connector for voltage monitoring and the AMP and GND connector for load measurements. Enabling the Controller In order to enable the controller, the board must be powered and a VID code must be set. If these steps have been properly followed, the regulator is enabled by toggling the “ENABLE” switch (EN1) to the ON position. When EN1 is switched, the voltage on the EN pin of the ISL6327 will rise above the ENLL threshold and the controller will begin the soft start sequence. The output voltage ramps up to the programmed VID setting, at which time the PGOOD indicator will switch from red to green. Signal Test Points There are many test points available on the ISL6327EVAL5 for monitoring of key signals. Monitoring test points include, VR_HOT and VR_RDY for monitoring the temperature FAULT outputs, OFS, IOUT, DAC, REF, COMP, EN, and DAC for monitoring control waveforms. There are also test points for monitoring VIN (VIN1 and VIN2) and VOUT (TPVCORE1 and TPGND1). For accurate measurements with the differential probes you must make sure that the ground terminal of your oscilloscope is connected to the ground plane of the ISL6327EVAL5. An easy way to do this is use a wire to connect the GND terminal of the scope to one of the GND test points on the ISL6327EVAL5 (TP10 for example). 2 AN1268.0 October 26, 2010 Application Note 1268 Component Selection With Coupled Inductors There are many parameters of the operation of the ISL6327 that can be modified and tested using the ISL6327EVAL5 evaluation board. Many control signals can also be monitored through on-board test points. For detailed theory of operation and component selection guidelines for the ISL6327 please refer to the ISL6327 datasheet available on the web at www.intersil.com. Key parameters that will be selected differently or otherwise impacted in the case where coupled inductors are used in the output filter are feedback compensation, DCR sense time constant, current sense resistor, droop control, and overcurrent set point. How to select these components will be covered in this section. PWM Modulation Scheme and Continuous Current Sense The ISL6327 adopts Intersil's proprietary Active Pulse Positioning (APP) modulation scheme to improve transient performance. APP control is a unique dual-edge PWM modulation scheme with both PWM leading and trailing edges being independently moved to provide the best response to transient loads. The PWM frequency, however, is constant and set by the external resistor between the FS pin and GND. To further improve the transient response, the ISL6327 also implements Intersil's proprietary Adaptive Phase Alignment (APA) technique. APA, with sufficiently large load step currents, can turn on all phases simultaneously. With both APP and APA control, ISL6327 can achieve excellent transient performance and reduce the demand on the output capacitors. Under steady state conditions the operation of the ISL6327 PWM modulator appears to be that of a conventional trailing edge modulator. Conventional analysis and design methods can therefore be used for steady state and small signal operation. The ISL6327 senses current continuously (no sample-andhold) on each channel for fast response to changes in inductor current. Continuous current sensing, APA and APP allow for very high bandwidth response to a load transient events. Coupled Inductor Details To further take advantage of the control and sensing features of the ISL6327 the use of coupled inductors in the output filter can be implemented. Coupling 2 phases on a single inductor core allows a reduction in phase inductance for fast transient response without the hit in efficiency due to larger phase ripple currents with an equivalent standard inductor. 3 With a standard single winding inductor the current waveform is dependant on the voltage at the two terminals of the inductor. The peak-to-peak ripple current in a synchronous buck application is determined by Equation 1. ( V IN – V OUT ) V OUT I PPsi = --------------------------------------------------------L fS V IN (EQ. 1) where VIN is the input voltage, VOUT is the output voltage, L is the standard inductance value, and fS is the switching frequency. The total output ripple current is determined by the sum of all of the phase currents and its magnitude is reduced by the interleaving of N number of phases. ( V IN – N V OUT ) V OUT I TotalPPsi = ---------------------------------------------------------------L fS V IN (EQ. 2) For a given Vin, Vout and fs, both the channel and total ripple current are determined by L, the standard inductance of each phase. For the case where there are two inductors coupled on one core, each providing the inductance for one phase in a synchronous buck converter, the ripple current for a single phase is now dependant on the voltages across both inductors as well as the magnetic properties of the coupled inductor. Consider the two phase coupled inductor drawn in Figure 1. L1 Iphase1 PHASE1 Iphase2 IOUT VOUT PHASE2 IOUT IPhase2 IPhase1 PHASE2 PHASE1 FIGURE 1. TWO PHASE COUPLED INDUCTOR RIPPLE CURRENT WAVEFORMS Note the dot convention. If positive current flows into the dot connected to PHASE1 then current will flow out of the dot connected to PHASE2. This means when one PHASE has a positive current slew rate so will the coupled PHASE. Figure 1 shows example waveforms for a simplified 2 phase case. AN1268.0 October 26, 2010 Application Note 1268 The equation for peak-to-peak ripple current and total output ripple current are dependent on the magnetic properties of the coupled inductor. With these equations it can be determined that the output current waveform and therefore the transient response is determined by: The two winding coupled inductor is essentially a transformer. Like any transformer it will have a specified winding ratio, winding inductance (or self inductance, L), and mutual inductance (LM). Parasitics will include leakage inductance (LLK) and winding resistance (DCR). All these parameters must be considered in optimizing the coupled inductor performance for a given application. L Tr = ( L – ( n ci – 1 )L M ) = L – L M An equivalent circuit for the two phase coupled inductor is shown in Figure 2. For the coupled inductor used in this reference design the windings are symmetrical and the turns ratio is 1:1. N=1 This term is the leakage inductance, LLK, of the two winding coupled inductor. The phase ripple current waveform, or steady state phase ripple current, is determined by the equivalent inductance in Equation 6: 2 2 ( V IN – V OUT ) ⎛ L – L M ⎞ ⎝ ⎠ L SS = ---------------------------------------------------------------------------( V IN – V OUT )L – L M V OUT (EQ. 6) Equations 5 and 6 will be used when selecting components in a two phase coupled inductor application. Current Sensing DCR L - LM DCR L - LM ISL6327 senses phase current continuously for fast response. ISL6327 supports inductor DCR sensing, or resistive sensing techniques. For more detail on the ISL6327 theory of operation please refer to the ISL6327 datasheet. FIGURE 2. TWO PHASE COUPLED INDUCTOR INDUCTOR DCR SENSING Each winding has a self inductance which is the total inductance that magnetizes the core. In an imperfect transformer some of the flux generated by the current through the winding will not couple through the core to the other winding. The mutual inductance is the portion of the winding inductance that is coupled with the other windings. Choosing the DCR current sense circuitry is straight forward when using standard inductors but a little more complicated when using coupled inductors. Consider the inductor DCR as shown in Figure 3. The channel current IL flowing through the inductor will also pass through the DCR. A simple R-C network across the inductor extracts the DCR voltage. VIN The leakage inductance is a measure of how much of the total flux does not couple to the other winding. A system of equations can be used to determine the phase peak-to-peak ripple current equation and total output peak-to-peak ripple current equation. LM DCR LLK DCR LLK VOUT ISL6609 + COUT For the two phase coupled inductor case the phase ripple current is shown in Equation 3: ⎛ ⎞ ⎜ ( V IN – V OUT )L – L M V OUT V OUT⎟ I PPci = ⎜ --------------------------------------------------------------------------- ⋅ -----------------⎟ V IN ⎟ ⎜ ⎛ L 2 – L 2⎞ ( f ) ⎝ ⎠ M ⎠ S ⎝ COUPLED INDUCTOR IL R VC(s) - LM (EQ. 5) C PWM(n) (EQ. 3) ISL6327 INTERNAL CIRCUIT RISEN(n) The total ripple current will be the sum of the phase currents and can be calculated using Equation 4: ( V IN – N V OUT ) V OUT I TotalPPci = ---------------------------------------------------------------( L – ( n ci – 1 )L M )f S V IN In CURRENT (EQ. 4) Where N is the number of phases in the multiphase converter, and nci is the number of inductors coupled on a single core, in this case nci = 2. ISEN-(n) SENSE + - ISEN+(n) CT DCR I SEN = I ----------------LR ISEN FIGURE 3. DCR CURRENT SENSING 4 AN1268.0 October 26, 2010 Application Note 1268 If the R-C network components are selected such that the RC time constant (= R*C) matches the inductor time constant (= L/DCR), the voltage across the capacitor VC is equal to the voltage drop across the DCR, i.e., proportional to the channel current. transformer since the leakage inductance is typically small compared to the self inductance.The coupled inductor in a multiphase application will have a higher percentage of leakage vs. self inductance so additional steps are needed to calculate the actual leakage inductance. With the internal low-offset current amplifier, the capacitor voltage VC is replicated across the sense resistor RISEN. Therefore the current out of ISEN+ pin, ISEN, is proportional to the inductor current. A calibrated bench RLC meter can be used for accurately measuring leakage. Equation 7 shows that the ratio of the channel current to the sensed current ISEN is driven by the value of the sense resistor and the DCR of the inductor. DCR I SEN = I L ⋅ ------------------R ISEN (EQ. 7) But how is the RC time constant selected in the coupled inductor case? The leakage inductance of the coupled inductor should be used as the inductance in the time constant calculation. The leakage inductance for the two phase coupled inductor is L - Lm. Because of the internal filter at ISEN- pin, one capacitor CT is needed to match the time delay between the ISEN- and ISEN+ signals. Select the proper CT to keep the time constant of RISEN and CT (RISEN x CT) close to 27ns. Determining The Leakage Inductance of a Coupled Inductor The leakage inductance of the CI must be determined to design and model with CI's, including using Equations 3-8. There are several methods for accurately determining the leakage inductance per phase of the coupled inductor; two methods are outlined here. Figure 4 depicts an equivalent magnetic circuit for the coupled inductor. LLK1 RLC METER LLK2 2 2 L LK = L – ⎛ L – ( L ⋅ L S )⎞ ⎝ ⎠ (EQ. 9) 5. Repeat the above steps to obtain the winding inductance and leakage of the secondary. Method 2 1. Short pins 4 and 3. The measured inductance will be the sum of the primary and secondary leakages. In the symmetrical, 1:1 winding ratio of the multiphase buck coupled inductor this will be 2*LLK. The average leakage for each winding can be determined by dividing by 2. IN06006 Specification Using Method 1 The coupled inductor used on the evaluation board is the IN06006. To use this inductor as an example to illustrate method 1 above refer to the IN06006 datasheet for the following steps: 1. The winding inductance listed in the IN06006 datasheet shows 315nH. So, L = 315nH. 2. Shorting the secondary and measuring the primary gives 150nH. Ls = 150nH. 3. The IN06006 winding ratio is 1:1. 4. The leakage inductance of this inductor can be calculated using Equation 9. LM 4 2. Short circuit the secondary winding, pins 2 and 3 in Figure 4. The measured inductance from pins 1 to 4 is the leakage inductance of the primary plus the reflected leakage from the secondary. Call this Ls. 4. The leakage can be calculated using Equation 9: (EQ. 8) 1 1. Leave the secondary winding, pins 2 and 3 in Figure 4, open circuit. The measured inductance from pins 1 to 4 is the primary winding inductance or self inductance. Call this L. 3. For this application the turns ratio is 1:1. An equation for selecting the resistor of the RC time constant for a two winding coupled inductor and a given C value is shown in Equation 8. Refer the ISL6327 datasheet for additional component selection guidelines.: L LK R = ---------------------DCR ⋅ C Method 1 3 TWO PHASE COUPLED INDUCTOR FIGURE 4. EQUIVALENT MAGNETIC CIRCUIT OF THE COUPLED INDUCTOR 2 L LK = 315 – ( 315 – ( 315 ⋅ 150 ) ) = 87nH So, the leakage inductance for the IN06006 is 87nH. The mutual inductance can be determined by Equation 5. Lm = L - LLK = 228nH. A conventional method for measuring leakage inductance in a transformer is to short the secondary and measure the inductance of the primary. This is a good approximation for a 5 AN1268.0 October 26, 2010 Application Note 1268 What Inductor Parameters Do I Use? The 87nH leakage inductance can be used in Equation 8 to calculate the required RC time constant match for DCR current sensing. As shown in Equation 5, the leakage inductance determines the total current waveform and therefore the small signal transient response. Use LLK as the phase inductance when calculating the regulator feedback compensation and small signal transient response. For steady state phase current calculations, use Equation 4. This equation will give the peak-to-peak inductor current waveforms for input ripple calculations, MOSFET selection, and efficiency estimates. The above analysis shows that a given transient inductance can be used while reducing the phase ripple current vs. an equivalent standard inductor. Load-Line Regulation and Component Selection EXTERNAL CIRCUIT CC RC COMP ISL6327 INTERNAL CIRCUIT DAC RREF + - FB RFB IDROOP + VDROOP VDIFF VOUT+ IAVG VCOMP ERROR AMPLIFIER VSEN + VOUT- - RGND DIFFERENTIAL REMOTE-SENSE AMPLIFIER FIGURE 5. OUTPUT VOLTAGE AND LOAD-LINE REGULATION Figure 5 shows that the average current of all active channels, IAVG flows from FB through a load-line regulation resistor, RFB. (EQ. 10) V DROOP = I AVG R FB The regulated output voltage is reduced by the droop voltage VDROOP. The output voltage as a function of the load current is derived by combining Equation 10 with the sensed current expression defined by the current sense method employed. ⎛ I OUT R X ⎞ V OUT = V REF – V OFS – ⎜ --------------- ------------------- R FB⎟ N R ⎝ ⎠ ISEN 6 Therefore, the equivalent load-line impedance (i.e., droop impedance) is: R FB R X R LL = ------------- ------------------N R ISEN (EQ. 12) Overcurrent Protection ISL6327 has two levels of overcurrent protection. Each phase is protected from a sustained overcurrent condition by limiting its peak current, while the combined phase currents are protected on an instantaneous basis. In instantaneous protection mode, the ISL6327 utilizes the sensed average current IAVG to detect an overcurrent condition. The average current magnitude can be approximated using Equation 7, the sensed current signal for an individual phase. The average current is continuously compared with a constant 85µA. Once the average current exceeds the reference current, a comparator triggers the converter to shut-down. For details on how the ISL6327 behaves in reaction to an overcurrent event refer to the ISL6327 datasheet. REF CREF Where VREF is the reference voltage, VOFS is the programmed offset voltage, IOUT is the total output current of the converter, RISEN is the sense resistor connected to the ISEN+ pin, RFB is the feedback resistor, N is the number of active channels, and RX is the DCR, or sense resistor, depending on the sensing method. For the individual channel overcurrent protection, the ISL6327 continuously compares the sensed current signal of each channel with the 120µA reference current. If one channel current exceeds the reference current, ISL6327 will pull PWM signal of this channel to low for the rest of the switching cycle. This PWM signal can be turned on next cycle if the sensed channel current is less than the 120µA reference current. The peak current limit of individual channel will not trigger the converter to shut-down. The overcurrent protection level for the above two OCP modes can be adjusted by changing the value of current sensing resistors. In addition, ISL6327 can also adjust the average OCP threshold level by adjusting the value of the resistor from IOUT to GND, R17 on the evaluation board. An overcurrent response will be initiated when the voltage on IOUT reaches 2V. Use Equation 7 to approximate the average current value. Equation 13 can be used to calculate the value of the resistor RIOUT based on the desired OCP level IAVG, OCP2. 2V R IOUT = -----------------------------------I AVG, OCP2 (EQ. 13) (EQ. 11) AN1268.0 October 26, 2010 Application Note 1268 Which Phases Should Be Coupled? Figure 1 has been duplicated in Figure 6 with some changes to the spacing of the PWMs modified to show the effect on the ripple current waveforms. The bold red and blue waveforms in Figure 6 show an example of how the phase current waveforms will change if the PWM spacing is changed. Best ripple reduction performance is achieved when the two coupled phases are 180 degrees phase-shifted. The ISL6327 in 6-phase mode fires phases sequentially, PWM1, PWM2, PWM3, PWM4, PWM5, PWM6. So, for optimal phase ripple current reduction PWM1-PWM4, PWM2-PWM5, and PWM3-PWM6 should be coupled. For optimal layout placement two sequential PWMs should not be placed next to one another. So, from left to right on a PCB, an example placement can be PWM1,PWM4,PWM2, PWM5, PWM3, PWM6. L1 Iphase1 PHASE1 Iphase2 IOUT Modifying the Board For Other Applications As shipped, the ISL6327EVAL5 is configured for 6 phase operation, a VR11 VID of 1.35V, and designed for operation up to 130A with a loadline of 1.25mΩ. The coupled inductors on board are IN06006. The inductor footprints on the board are large enough to accommodate the footprints of other coupled inductors for evaluation purposes. The following procedure can be used to modify the board for 4 phase evaluation. Four Phase VR11 05A Configuration, LL = 1mΩ 1. Change Feedback Compensation: R4 = 2.32k, R7 = 100, C6 = 390pF, C5 = 330pF, R5 = 9.09k, C7 = 33pF 2. Change the IOUT resistor to decrease the overcurrent set point: R17 = 36.5k which will give IOC = 120A 3. Change the DCR sense resistors: R22, R24, R26, R28, R30, R32 = 1.3k VOUT 4. Move jumper hats on PWM5 and PWM6 pouts: Move hats on JP_4P_SEL1 and JP_5P_SEL2 from pins 2 and 3 to short pins 1 and 2. This will disable PWM5 and PWM6 PHASE2 IPhase1 5. The 6 phase board is configured with (40) 10µF ceramic capacitors in the output filter. For 4 phases 05A configuration add 10 to 20 additional 10µF ceramic capacitors to the output filter. There are plenty of additional 1206 footprints around the socket to do this. PHASE2 6. Remove unused power stage: Remove INDUCTORS L3, MOSFETS Q3L1, Q3U1, Q6L1, Q6U1, DRIVERSU4, and U7. PHASE1 7. Remove R79 which is connecting PWM5 to DRIVER U6 IOUT IPhase2 FIGURE 6. COUPLED INDUCTOR CURRENT WAVEFORMS 8. Place a 0Ω resistor on R80 to connect PWM3 to DRIVER U6. 9. On the back of the PCB remove R84 and R85. Place 0Ω resistors on R90 and R91. 10. Follow the Quick Start Evaluation procedure on page 1 to power up the board. 7 AN1268.0 October 26, 2010 Application Note 1268 ISL6327EVAL5 Six Phase Performance EN 5V/DIV EN 5V/DIV VR_RDY 5V/DIV VR_RDY 5V/DIV VCORE 0.5V/DIV VCORE 0.5V/DIV 50µs/DIV 0.5ms/DIV FIGURE 7. START-UP SEQUENCE FIGURE 8. SHUT-DOWN SEQUENCE VCORE 20mV/DIV VCORE 20mV/DIV 5µs/DIV 5µs/DIV FIGURE 9. NO LOAD RIPPLE ~10mV FIGURE 10. 130A RIPPLE ~12mV VCORE 50mV/DIV VCORE 50mV/DIV ILOAD 1V/DIV ILOAD 1V/DIV 10µs/DIV FIGURE 11. TRANSIENT RESPONSE 20A to 120A IN 1200A/µs 8 10µs/DIV FIGURE 12. TRANSIENT RESPONSE 120A to 20A IN 1200A/µs AN1268.0 October 26, 2010 Application Note 1268 ISL6327EVAL5 Six Phase Performance (Continued) 1.35 90 88 1.30 86 1.25 VMAX VOUT (V) EFFICIENCY (%) 92 84 82 VOUT 1.20 80 VMIN 78 1.15 76 74 72 1.10 0 10 30 50 70 90 IOUT (A) 110 130 150 0 20 40 60 80 100 120 140 160 IOUT (A) FIGURE 13. VR EFFICIENCY VIN = 12V, VID = 1.35V, LL = 1.25mΩ, VOUT MEASURED AT INDUCTOR FIGURE 14. VCORE LOADLINE REGULATION FROM 0A TO 150A VCORE 0.5V/DIV .5ms/DIV FIGURE 15. VID-ON-THE-FLY OPERATION 0.6V to 1.55V 9 AN1268.0 October 26, 2010 Application Note 1268 ISL6327EVAL5 Four Phase Performance EN 5V/DIV EN 5V/DIV VR_RDY 5V/DIV VR_RDY 5V/DIV VCORE 0.5V/DIV VCORE 0.5V/DIV 50µs/DIV 0.5ms/DIV FIGURE 16. START-UP SEQUENCE FIGURE 17. SHUT-DOWN SEQUENCE VCORE 20mV/DIV VCORE 20mV/DIV 5µs/DIV 5µs/DIV FIGURE 18. NO LOAD RIPPLE ~6mV FIGURE 19. 130A RIPPLE ~11mV VCORE 50mV/DIV VCORE 50mV/DIV ILOAD 1V/DIV ILOAD 1V/DIV 10µs/DIV FIGURE 20. TRANSIENT RESPONSE 35A to 100A IN 50ns 10 10µs/DIV FIGURE 21. TRANSIENT RESPONSE 100A to 35A IN 50ns AN1268.0 October 26, 2010 Application Note 1268 ISL6327EVAL5 Four Phase Performance (Continued) 92 1.40 VMAX 86 84 1.35 VOUT VOUT (V) EFFICIENCY (%) 90 88 82 80 78 1.30 VMIN 76 74 72 1.25 0 10 20 30 40 50 60 IOUT (A) 70 80 90 100 110 FIGURE 22. VR EFFICIENCY VIN = 12V, VID = 1.4V, LL = 1.0mΩ, VOUT MEASURED AT INDUCTOR 0 20 40 60 80 100 120 IOUT (A) FIGURE 23. VCORE LOADLINE REGULATION FROM 0A TO 100A Summary References The ISL6327EVAL5 evaluation board provides a high performance VRD solution highlighting the ISL6327 advanced multiphase controller with the use of a coupled inductor and low capacitance output filter. Intersil documents are available on the web at www.intersil.com. [1] ISL6327 Data Sheet, Intersil Corporation, File No. FN9276 For detailed theory of operation, component selection and layout guidelines refer to the ISL6327 datasheet. [2] ISL6609 Data Sheet, Intersil Corporation, File No. FN9221 The following pages provide a board schematic and bill of materials to support implementation of this and similar solutions. [3] IN06006 Coupled Inductor Datasheet ICE Components, www.icecomponents.com 11 AN1268.0 October 26, 2010 Controller Circuit ntroller circuit VCC5 R22 1.21k VCC5 R21 R34 1.5k C12 0.1u R24 1.21k R8 2.2 1 ISL6327 U1 Vc5 R56 DNS 2 TP14 VR_RDY 12 21 R1 10 C8 1u C2 DNS C3 DNS R2 10 VSEN C4 DNS R36 R53 DNS C5 330pF C7 33p C9 10n R9 1k 25 27 26 PWM3 ISEN3ISEN3+ 36 34 35 PWM4 ISEN4ISEN4+ 30 28 29 VDIFF IDROOP PWM5 ISEN5ISEN5+ 24 22 23 15 FB 14 COMP PWM6 ISEN6ISEN6+ 37 39 38 13 REF OVP 44 TP5 DAC 12 DAC IOUT 11 10 42 R11 41.2k PWM2 ISEN2ISEN2+ 16 R5 12.1k R10 20k 31 33 32 RGND VSEN 0 TP18 OFS PWM1 ISEN1ISEN1+ 17 TP4 REF Vc5 41 VR_RDY R4 4.32k C6 390pF EN_VTT 18 19 0 R7 100 40 45 R35 C1 DNS VID7 VID6 VID5 VID4 VID3 VID2 VID1 VID0 VRSEL EN_PWR R12 100k OFS 46 VR_HOT 47 TM 48 FS 43 SS 20 TCOMP 49 VR_FAN R25 Vc5 R55 Thermistor C14 0.1u 402 R27 402 R29 TP11 GND1 TP12 GND1 RC1 100K R28 1.21k ISEN4- C17 0.1u ISEN4+ C18 0.1u R30 1.21k 402 ISEN5- C19 0.1u ISEN5+ C20 0.1u CF5 68p R32 1.21k R31 402 C21 0.1u VCC5 CF6 68p C22 0.1u R18 1K TP15 VR_FAN PWM1 VCC5 PWM2 JP_2P_SEL1 TP7 TM 1 2 R16 1K 3 TP3 IOUT R17 C48 41.2k 100p R54 10K 1 3 PWM4 JP_3P_SEL3 C10 DNS PWM3 For 6phase operation place all 4 PWM jumpers on pins 2 and 3 jumper_3pin 2 TP16 VR_HOT jumper_3pin JP_4P_SEL1 TP10 GND1 ISEN3- C15 0.1u C16 0.1u CF4 68p 10k TP9 GND1 R26 1.21k ISEN3+ CF3 68p VCC5 RN2 6.8k ISEN2- C13 0.1u ISEN2+ CF2 68p TP13 EN R15 1k GND 402 1 IOC target 169A Vc5 2 3 PWM5 jumper_3pin JP_5P_SEL2 1 2 3 jumper_3pin PWM6 ISEN6ISEN6+ Application Note 1268 TP6 VDIFF 1 2 3 4 5 6 7 8 9 VID7 VID6 VID5 VID4 VID3 VID2 VID1 VID0 VTTVRSEL RGND VCC R14 1k R23 3 2 Q24 2N7002 R3 10 6 1 2 3 4 R13 10k VCC12 VCC5 RED 4 EN1 GREEN TP8 GND1 ISEN1- C11 0.1u ISEN1+ CF1 68p CR2 VR_RDY TP17 COMP 402 VCC12 1 3 R33 1k AN1268.0 October 26, 2010 Output Capacitors and LGA775 VID Connections U100 VTTVID0 AM2 VTTVID1 AL5 VTTVID2 AM3 VTTVID3 AL6 VTTVID4 AK4 AN5 AN6 VCC_DIE AN3 VTTVID5 AL4 VTTVID6 AM5 VCC VTTVID7 AM7 VSS 0 R40 0 VSEN Install R40, R42 for Die Sensing connection RGND VCORE BNC1 DNS 1 2 3 AN7 Place those resistors and caps close to test point C66 DNS 4 5 13 VTTVRSEL R42 VSS_DIE AN4 R_SEL2 DNS R41 0 R74 DNS VOUT2 Vout- VOUT1 Vout+ R43 DNS TP1 VCORE VSEN VTT_R1 Install R39, R41 for Socket Sensing connection 0 CT1 1u CT2 2.2n CT3 2.2n R39 CO1 560u CO2 560u CO3 560u CO4 560u CO5 560u CO6 560u CO7 560u CO8 560u CO9 560u CO10 560u CO11 560u CO12 560u VTT_R2 0 Those caps are for Low frequency operation only. Do not install for high frequncy operation. CO13 100u CO14 100u CO15 100u CO16 100u CO17 100u CO18 100u CO19 100u CO20 100u CO21 100u CO22 100u Place those 10 caps on top side CO23 10u CO24 10u CO25 10u CO26 10u CO27 10u CO28 10u CO29 10u CO30 10u CO31 10u CO56 10u CO57 10u CO58 10u CO59 10u Place those 9 caps inside of CPU carvity on top side CO32 10u CO33 10u CO34 10u CO35 10u CO36 10u CO37 10u CO38 10u CO39 10u Place those 15 caps on bottom side 1 1 VCORE1 GND1 V_CORE GND CO40 10u CO50 10u CO60 10u CO61 10u CO62 10u CO63 10u CO64 10u CO65 10u CO66 10u CO67 10u CO68 10u CO69 10u CO70 10u CO71 10u CO72 10u CO73 10u CO74 10u CO75 10u CO76 10u CO78 10u CO77 10u CO80 10u CO79 10u Place those 25 caps on top side CO51 10u CO52 10u CO53 10u CO54 10u CO55 10u CO41 10u CO42 10u CO43 10u \CO44 10u CO45 CO46 10u 10u CO47 10u CO48 10u CO49 10u CO83 330u Place those 9 caps inside CPU Carvity area on bottom side CO81 330u CO82 330u Optional SP caps For 6phase operation and 100A load step; board is populated with 40*10uF 1206 capacitors Intersil Corporation Intersil RTP Size B D t Title ISL6327 CI EVALUATION 5 BOARD F id J l 28 2006 Sh t 2 f 5 Rev A Application Note 1268 RGND 0 VCORE AN1268.0 October 26, 2010 Power Stage Power Stage VIN1 Vin+ VINF VIN2 Vin- Put those 2 test points close to input inductor VCC12 L_IN1 150n TPVCORE1 VCORE VCC5 D BT 2 PWM 7 C26 10u Q1U1 HAT2168H EN 6 VCC 5 CI_1 470u (OSCON) Q1L1 HAT2165H 4 9 3 1 RS1 LG GL GND PWM1 1 C25 10u C24 0.22u U2 isl6609 PH UG 8 RV1 0 TPGND1 GND 3.3 4 2 CS1 2200p 14 C23 1u L1 L1 is used for 6-phase or 4-phase mode 3 VINF UG PWM 6 VCC 5 0 0 Q4L1 HAT2165H ISEN1+ R59 ISEN1- R77 0 3.3 7 8 PWM 6 5 Q2L1 HAT2165H 4 9 3 1 RS2 LG EN VCC 3.3 4 2 CS2 2200p C27 1u L2 L2 is only used for 6-phase 3 VINF BT 2 PWM C59 10u Q5U1 HAT2168H EN 6 VCC 5 C61 10u R60 0 ISEN2+ R61 0 ISEN2- LG RS5 Q5L1 HAT2165H 4 R80 DNS C55 0.22u PH UG 1 GL GND R79 0 U6 isl6609 7 8 IN06006 9 3 PWM3 ISEN2- C30 10u Q2U1 HAT2168H PH UG BT 2 GL GND 1 C29 10u C28 0.22u U3 isl6609 ISEN2+ R93 DNS R84 0 3.3 CS5 2200p B C64 1u ISEN5+ R85 0 ISEN5- R90 DNS VINF ISEN3+ BT 2 PWM C33 10u Q3U1 HAT2168H 6 5 3.3 Q3L1 HAT2165H 4 9 3 1 RS3 LG EN VCC 4 2 CS3 2200p L3 is only used for 6-phase IN06006 7 PWM AN1268.0 October 26, 2010 GL GND C60 10u Q6U1 HAT2168H C62 10u R62 0 ISEN3+ R63 0 ISEN3- EN 6 VCC 5 BT 9 3 C56 0.22u RS6 LG 2 4 1 U7 isl6609 PH UG 8 VINF PWM6 L3 3 C31 1u A ISEN3- C34 10u PH UG 1 GL GND R89 0 C32 0.22u U4 isl6609 7 8 R91 DNS PWM3 Application Note 1268 VINF C PWM5 ISEN4- R92 DNS C63 1u R82 0 ISEN4+ R78 0 CS4 2200p PWM2 VCORE R58 RS4 LG R81 DNS C57 10u PH EN BT GL GND 2 C58 10u Q4U1 HAT2168H 4 PWM2 1 R88 0 9 3 PWM4 U5 isl6609 7 8 IN06006 C54 0.22u Q6L1 HAT2165H 3.3 CS6 2200p R86 0 R87 0 ISEN6+ Intersil Co ISEN6- Intersil RTP C65 1u Size C Title ISL6327 CI EVALUATION VID Generator and Input Power Connectors or and Input power connectors 5V +5V R48 10k SW1 SW DIP-4 R49 10k R50 10k R51 10k RVID0 2k R52 10k VR11/VR10 IPF/IA32 Repetitious/Manual DEMO/VTT J_VID0 jumper_3pin 1 VTTVID0 U8 PIC16F874A-PT +5V 15 SW2 SW DIP-8 VID Code +5V +5V RB0 RB1 RB2 RB3 RB4 RB5 RB6 RB7 8 9 10 11 14 15 16 17 38 39 40 41 2 3 4 5 RD0 RD1 RD2 RD3 RD4 RD5 RD6 RD7 RA0 RA1 RA2 RA3 RA4 RA5 19 20 21 22 23 24 OSC1 30 25 26 27 RE0 RE1 RE2 OSC2 31 SW3 VID Load 3 4 R46 10k 7 28 VCC VCC1 C50 0.01u 29 6 GND GND1 2 VID1 2 VID2 2 VID3 2 VID4 2 VID5 2 VID6 2 VID7 1 VTTVID1 3 2k J_VID2 jumper_3pin RVID2 1 VTTVID2 TP2 TP 3 2k STEP1 Step J_VID3 jumper_3pin RVID3 1 VTTVID3 3 2k Y1 NC NC1 NC2 NC3 12 13 33 34 MCLR 18 J_VID4 jumper_3pin RVID4 C52 33p 1 VTTVID4 C53 33p 3 2k J_VID5 jumper_3pin RVID5 1 VTTVID5 3 2k J_VID6 jumper_3pin RVID6 1 VTTVID6 3 C51 1u 2k J_VID7 jumper_3pin RVID7 1 VTTVID7 3 5V1 5V +5V 5V_GND1 VCC5 5V_PWR1 24 PIN POWER 12V1 R83 0 R44 0 R45 0 5V_6P VCC12 12V_PWR1 2 GND GND0 +12V 5 1 12V +3.3V +3.3VA +3.3VB +3.3VC 4 6 21 22 23 +5V +5VA +5VB +5VC +5VD PWR_OK 3 4 ATX 12V AUX POWER C47 10u C49 10u 9 +5VSB 10 11 +12V1A +12V1B 14 -12V 16 PS_ON# GND GND0 GND1 GND2 GND3 GND4 GND5 GND6 NC 0 3 5 7 15 17 18 19 24 VTTVRSEL R_SEL1 8 20 Intersil Corporation Intersil RTP 25 5 1 2 12 13 25 12V_GND1 Size B Title ISL6327 CI EVALUATION 5 BOAR Application Note 1268 1 2 RC0 RC1 RC2 RC3/SCL RC4/SDA RC5 RC6/TX RC7/RX VID0 J_VID1 jumper_3pin RVID1 32 35 36 37 42 43 44 1 2 3 4 5 6 7 8 9 1 10 R47 10k 2 3 2k AN1268.0 October 26, 2010 Application Note 1268 Bill of Materials QTY REF DESIGNATOR 3 C52, C53, C7 33pF, 50V COG 0603 Cap Various REEL 1 C48 100pF, 50V COG 0603 Cap Various REEL 6 CF1, CF2, CF3, CF4, CF5, CF6 68pF, 50V X7R 0805 Cap Various REEL 1 C5 330pF, 50V X7R 0603 Cap Various BAG 1 C6 390pF 50V COG 0603 Cap Various BAG 4 C3, C2, CT2, CT3 2.2nF, 50V X7R 0603 Cap NIC NMC0603X7R222K REEL 2 C9, C50 10nF, 50V X7R 0603 Cap NIC NMC0603X7R103K REEL 12 C12, C14, C16, C18, C20, C22, C11, C13, C15, C17, C19, C21 6 C24, C28, C32, C54, C55, C56 8 DESCRIPTION VENDOR 0.1µF, 16V X7R 0603 Capacitor MURATA 0.22µF, 50V Y5V 0603 Cap MURATA C8, C23, C27, C31, C51, C63, C64, C65 1µF, 16V X5R 0603 Cap VENDOR P/N PKG BAG GRM188F51H224Z BAG MURATA GRM188R61C105K BAG 1 CT1 1µF, 16V X7R 1206 Cap MURATA GRM319R71C105K BAG 1 C49 10µF, 16V Y5V 0805 Cap MURATA GRM21BF51C106Z BAG 58 CO23, CO24, CO25, CO26, CO27, CO28, CO29, CO30, CO31, CO32, CO33, CO34, CO35, CO36, CO37, CO38, CO39, CO40, CO41, CO42, CO43, CO44, CO45, CO46, CO47, CO48, CO49, CO50, CO51, CO52, CO53, CO54, CO55, CO56, CO57, CO58, CO59, CO60, CO61, CO62, CO63, CO64, CO65, CO66, CO67, CO68, CO69, CO70, CO71, CO72, CO73, CO74, CO75, CO76, CO77, CO78, CO79, CO80 10µF, 6.3V X7R 1206 Capacitor MURATA GRM31CR70J106M REEL 0 13 C25, C26, C29, C30, C33, C34, C57, C58, C59, C60, C61, C62 100µF, 6.3V X5R 1210 Capacitor MURATA GRM31CR60J107M REEL 10µF, 16V X5R 1206 Capacitor MURATA GRM31CR61C106K BAG 470µF, 16V Sanyo OSCON Sanyo 16SEPC470M 0 5% Resistor; 0603 Various 1 CI_1 29 R39, R41, R58, R59, R60, R61, R62, R35, R36, R63, R75, R76, R79, R82, VTT_R1, VTT_R2, R_SEL1, R82, R79, R88, R89, R77, R78, R84, R85, R86, R87, R40, R42 4 R44, R45, R83, RV1 0 5% Resistor; 1206 Various REEL 1 R8 2.2 5% Resistor; 1206 Various REEL 6 RS1, RS2, RS3, RS4, RS5, RS6 3.3 Resistor, 5%, 1206 Various REEL 3 R1, R2, R3 10 5% Resistor; 0603 Various REEL 6 RF1, RF2, RF3, RF4, RF5, RF6 12 1% Resistor; 0603 Various REEL 6 R21, R23, R25, R27, R29, R31 402 1% Resistor; 0603 Various REEL 1 R7 200 1% Resistor; 0603 Various 6 R9, R15, R16, R18, R33, R34 1k 1% Resistor; 0603 NIC 8 RVID0, RVID1, RVID2, RVID3, RVID4, RVID5, RVID6, RVID7 2k 1% Resistor; 0603 Various BAG 1 R4 4.32k 1% Resistor; 0603 Various BAG 1.21k 1% Resistor; 0603 Various 6 R22, R24, R26, R28, R30, R32 10 R13, R43, R46, R48, R49, R50, R51, R52, R54, R55 1 1 BAG REEL REEL NRC06F1001TR REEL BAG 10k 1% Resistor; 0603 NIC NRC06F1002TR REEL R5 12.1k 1% Resistor; 0603 NIC NRC06F1002TR REEL R10 20k 1% Resistor; 0603 NIC NRC06F2002TR REEL 16 AN1268.0 October 26, 2010 Application Note 1268 Bill of Materials (Continued) QTY REF DESIGNATOR 2 R11, R17 2 R12, RC1 1 R47 1 RN2 THERM_6.8K_0805 3 L1, L2, L3 1 LIN_1 6 Q1U1, Q2U1, Q3U1, Q4U1, Q5U1, Q6U1 6 DESCRIPTION VENDOR VENDOR P/N PKG NIC NRC06F1003TR REEL 100k 1% Resistor; 0603 NIC NRC06F1003TR REEL 10k x 8 Resistor Array AVX RNA4A8E103JT REEL Vishay NTHS0805N02N6801 BAG 41.2k 1% Resistor; 0603 87nH/64A Coupled Inductor (0.55mΩ DCR) ICE IN-06006 DNS 150nH/40A Inductor (0.48mΩ DCR) Cooper FP4-150 REEL Upper MOSFETs Hitachi HAT2168H or RJK0305 BAG Q1L1, Q2L1, Q3L1, Q4L1, Q5L1, Q6L1 Lower MOSFETs Hitachi HAT2165H or RJK0301 BAG Crystal 16.000 MHz HC49/US ECS ECS-160-20-4 BAG 1 Y1 6 U2, U3, U4, U5, U6, U7 Sync Rec Buck Drvr 5V QFN Intersil ISL6609CR (QFN) TUBE 1 U1 Multiphase Buck Voltage Regulator Intersil ISL6327CR BAG 1 U8 8-BIT Microchip Cntrl Microchip PIC16F874A-I/PT BAG 2 CR1, CR2 4P LED 3X2.5MM SMD Luminex SSL-LXA3025IGC BAG 1 Q24 N-Ch MOSFET SOT-23 Fairchild 2N7002 BAG 1 SW1 4 Pin DIP Switch CTS 219-4LPST TUBE 1 SW2 8 Pin DIP Switch 1 SW3 Momentary Pushbutton Switch 219-8LPST TUBE EVQ-QWT03W BAG 1 EN1 ITT GT11MSCKETR BAG 1 5V_PWR1 24 Pin ATX Connector Molex 39-29-9242 BAG 1 12V_PWR1 4 Pin Power Connector Molex 39-29-9042 BAG 17 STEP1, VIN1, VIN2, VOUT1, VOUT2, VCORE1, TP1, TP2, TP3, TP4, TP5, TP13, TP14, TP15, TP16, TP17, TP18 Test Points Keystone 5002 BAG 5 TP8, TP9, TP10, TP11, TP12 Test Points, Turret 0.281 Height Keystone 1514-2 BAG 1 TP1 O'scope Probe Test Point Tektronix K131-4244-00 BAG 12 J_VID0, J_VID1, J_VID2, J_VID3, J_VID4, J_VID5, J_VID6, J_VID7, JP_4P_SEL1, JP_2P_SEL1, JP_3P_SEL3, JP_5P_SEL2 3 Pin Header AMP/TYCO A26512-ND BAG 2 5V1, 12V1 Banana Jack Keystone 7006K BAG 2 5V_GND1, 12V_GND1 Banana Jack Keystone 7007K 1 BNC1 BNC connector 2 VCORE1, GND1 Terminal Lugs 5 5 on the back of the board 1 47 Toggle Switch Mini SPDT SMD CTS Panasonic U100 31-5329-52RFX BAG Burndy KPA8CTP BAG FOXCONN LGA775 TRAY Bumpons CPU socket R53, R56, C1, C6, C7, C10, R_SEL2, Not Populated List CO1, CO2, CO3, CO4, CO5, CO6, CO7, CO8, CO9, CO10, CO11, CO12, CO81, CO82, CO83, R81, R80, R92, R93, R90, R91, R43, R74, C66, CS1-6, CO13, CO14, CO15, CO16, CO17, CO18, CO19, CO20, CO21, CO22 DNS Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that the Application Note or Technical Brief is current before proceeding. For information regarding Intersil Corporation and its products, see www.intersil.com 17 AN1268.0 October 26, 2010