HIP6302EVAL1 - Multiphase Power Conversion for AMD Athlon Processors up to 35A TM Application Note February 2002 AN9888.1 Author: Matt Harris Introduction Each generation of computer microprocessor brings performance advances in computing power. Performance improvements are made possible by advances in fabrication technology that enable greater device density. Newer processors are operating at lower voltages and higher clock speeds both of which contribute to greater demands on the microprocessor core voltage supply in terms of higher peak currents and higher current-slew rates. Intersil’s family of multi-phase DC-DC converter solutions provide the ideal solution to supply the core-voltage needs of present and future high-performance microprocessors. Intersil HIP6302 and HIP6601 The HIP6302 controller IC works with two HIP6601A or HIP6603A single-channel driver ICs or a single HIP6602A dual-channel driver IC [3] to form a highly integrated solution for high-current, high slew-rate applications. The HIP6302 regulates output voltage, balances load currents and provides protective functions for two synchronous-rectified buck-converter channels. VSEN 10 x 0.9 PGOOD VCC 15 16 POWER-ON RESET (POR) UV + - x 1.15 PVCC 7 VCC 6 2 BOOT 1 UGATE +5V 10k 8 3 SHOOT THROUGH PROTECTION CONTROL LOGIC FS/DIS 10k CLOCK AND SAWTOOTH GENERATOR S OVP + - The HIP6601A is a driver IC capable of delivering up to 2A of gate-charging current for rapidly switching both MOSFETs in a synchronous-rectified bridge. The HIP6601A accepts a single logic input to control both upper and lower MOSFETs. Adaptive shoot-through protection is provided on both switching edges to provide optimal dead time, and bootstrap circuitry permits greater enhancement of the upper MOSFET. For a more detailed description of the HIP6601A, refer to the HIP6601A Data Sheet [2]. PWM THREE STATE OV LATCH provides feedback for droop compensation and over-current protection. A five-bit DAC provides a digital interface to program the 1% accurate reference and a window comparator toggles PGOOD if the output voltage is out of range and acts to protect the load in case of over voltage. For more detailed descriptions of the HIP6302 functionality, refer to the HIP6302 Data Sheet [1]. 8 PHASE 5 LGATE 4 GND FIGURE 2. HIP6601A BLOCK DIAGRAM SOFT START AND FAULT LOGIC COMP 6 VID4 VID3 VID2 VID1 VID0 1 2 3 4 5 PWM + ∑ - PWM + DAC + - E/A 13 PWM1 + - ∑ - 12 PWM2 + - The HIP6302EVAL1 Board and Reference Design With the VID jumpers set to 1.7V (00110), the evaluation board meets the output voltage and current specifications indicated in Table 1. TABLE 1. HIP6302EVAL1 OUTPUT PARAMETERS CURRENT DETECTION MIN MAX Static Regulation 1.65V 1.75V Transient Regulation 1.60V 1.85V Over-Voltage Protection 1.90V 2.00V Continuous Load Current - 35A Over-Current Trip Level 41A 57A Load-Current Transient - 35A/µs FB 7 ∑ 14 ISEN1 + 11 ISEN2 + 9 GND FIGURE 1. HIP6302 BLOCK DIAGRAM The integrated high-bandwidth error amplifier provides voltage regulation, while current-sense circuitry maintains phase-current balance between the two power channels and 1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 321-724-7143 | Intersil (and design) is a trademark of Intersil Americas Inc. Copyright © Intersil Americas Inc. 2002. All Rights Reserved Application Note AN9888 The HIP6302EVAL1 evaluation board incorporates a reference design intended to meet the core-voltage requirements for AMD Athlon microprocessors up to 35A. Additional circuitry is provided to facilitate circuit evaluation including input and output power connectors, VID jumpers, numerous probe points, an LED power-good indicator, and a load-transient generator. Powering the HIP6302EVAL1 Start Up The waveforms in Figure 3 demonstrate the normal start-up sequence with the HIP6302EVAL1 connected to a 55mΩ load. After FS/EN is released, VCORE exhibits a linear ramp until reaching its 1.7V set point. The gradual increase of VCORE over approximately 5ms limits the current required from the input supply, ICC5, to a level that does not strain the supply. The HIP6302 asserts PGOOD once VCORE is within regulation limits. For convenience, the HIP6302EVAL1 provides two methods of making input power connections. The 20-pin header, J1, interfaces with a standard ATX power supply and may be the most convenient method of powering the board. FS/EN, 5V/DIV J2, J3, and J4 are standard banana-jack connectors that can be used to supply power using bench-top power supplies. These inputs provide greater versatility in testing and design validation by allowing the 12V and 5V power-input voltage levels to be varied independently. In this way power-on level and power-sequencing issues can be easily examined. 0V To start the evaluation board, insert the 20-pin connector from an ATX supply into J1. If using bench-top supplies, connect a 12V supply to J2 and a 5V supply to J3. Connect the grounds from both supplies to J4. 0A VCORE, 1V/DIV 0V ICC5, 10A/DIV PGOOD, 5V/DIV 0V 1ms/DIV Important FIGURE 3. HIP6302EVAL1 START-UP WAVEFORMS There are two things to consider when using bench-top supplies. If the 5V supply is applied prior to the 12V supply, the HIP6302 will begin operating before the HIP6601As. This allows the HIP6302 to complete its soft-start cycle before the drivers are capable of switching power to the output. When the 12V power input is then applied, there is a large transient as the controller tries to instantly bring the output to its fullvoltage level. This can result in an overcurrent protection cycle and an abnormal start-up waveform. It can be avoided by applying 5V supply after or at the same time as the 12V supply or by using an ATX power supply. The second problem can occur when operating the transient load generator. Not all bench-top and ATX power supplies are capable of responding to load transients, and they may allow a momentary voltage dip on VCC5. This can activate the power-on-reset function in the HIP6302 and cause the output power to cycle. It can be remedied by connecting a 5600µF or larger capacitor between VCC5 and ground. The capacitor, if necessary, simulates the distributed capacitance that exists on the computer motherboard. 2 Transient Response The HIP6302EVAL1 is equipped with a load-transient generator that applies a 0–36A transient load current with rise and fall rates of approximately 35A/µs. The duration of the transient is between 100µs and 200µs, and the repetition rate is kept low in order to limit power dissipation in the load MOSFETs and resistors. Removal of the HI/LO jumper (JP2) causes the current to decrease from about 36A to about 31A. The load-transient generator operates when the HIP6302EVAL1 is properly connected to a 12V power source and SW1 is in the ON position. Operation ceases when SW1 is moved into the OFF position or 12V is removed from the board. The HIP6302EVAL1 achieves the specified transient performance while maintaining a favorable balance between low cost, high efficiency and small profile. When the duty cycle changes rapidly in response to a transient load current, the inductor current immediately begins to change in order to meet the demand. During the time the inductor current is increasing, the output-filter capacitors are supplying the load. It follows that the amount of required capacitance decreases as the capability of the inductors to rapidly assume the load current increases. Athlon™ is a trademark of Advanced Micro Devices, Inc. Application Note AN9888 Figure 4 shows the core voltage, inductor current, and PWM signals changing in response to the transient load current. The upper waveform shows the core voltage deviating from its no-load setting of 1.72V to a minimum of about 1.62V upon the application of current. The voltage then settles to its 1.67V full-load setting. On load removal, the core voltage peaks at a level of 1.78V before settling again to its 1.72V no-load setting. Although the specified operating range allows deviations as low as 1.60V and as high as 1.85V, a minimum of 20mV is reserved to allow for the reference tolerance and the tolerances of other components that contribute to the overall system accuracy. The close up in Figure 6 shows the core-voltage, inductorcurrent and PWM signals changing in response to the trailing edge of the transient load current. Again, the duty cycles immediately decrease to zero, and the inductors begin shedding load current at the maximum rate. Note that the inductor currents briefly go negative as the transient settles. The capacitors are slightly over charged at the end of the transient, and the discharge path is in the reverse direction through the inductors. CORE VOLTAGE, 50mV/DIV 1.7V CORE VOLTAGE, 50mV/DIV 1.7V INDUCTOR CURRENTS, 10A/DIV INDUCTOR CURRENTS, 10A/DIV 0A PWM1, 10V/DIV 0V 0A 0V 0V 0V PWM1, 10V/DIV PWM2, 10V/DIV PWM2, 10V/DIV 5µs/DIV FIGURE 6. TRANSIENT-RESPONSE TRAILING EDGE Overcurrent Protection 20µs/DIV FIGURE 4. HIP6302EVAL1 TRANSIENT RESPONSE Figure 5 is a close-up showing the core-voltage, inductorcurrent and PWM signals responding at the leading edge of the transient load current. The PWM signals increase to their maximum duty cycle of 75% on the first pulse following the start of the transient. The inductor currents begin to increase immediately and are carrying all of the load within 10µs. The very fast transient response is due to the precision 18MHz error amplifier and optimal compensation of the control loop. When the current out of either ISEN pin exceeds 82µA, the HIP6302 detects an overcurrent condition and responds by placing the PWM outputs into a high-impedance state. This signals the HIP6601 to turn off both upper and lower MOSFETs in order to remedy the overcurrent condition.This behavior is seen in Figure 7 where PWM1 goes immediately to 2.5VDC when the output current reaches approximately 50A. The output voltage then quickly falls to zero. 1.7V OUTPUT CURRENT, 20A/DIV CORE VOLTAGE, 50mV/DIV 0A INDUCTOR CURRENTS, 10A/DIV CORE VOLTAGE, 500mV/DIV 0V PWM1, 5V/DIV 0A PWM1, 10V/DIV 0V 0V PWM2, 10V/DIV 50µs/DIV 0V 5µs/DIV FIGURE 5. TRANSIENT-RESPONSE LEADING EDGE 3 FIGURE 7. OVERCURRENT BEHAVIOR Application Note AN9888 After the initial over-current trip, the HIP6302 waits for a period of time equal to 2048/fSW (fSW is the switching frequency) before initiating a soft-start cycle. If the over-load condition remains, another over-current trip will occur before the end of the soft-start sequence. This repetitive overcurrent cycling is illustrated in Figure 8, and will continue indefinitely unless the fault is cleared or power to the converter is removed. Because of the wait period, the worst case power delivered during overcurrent cycling is equal to 45% of the power delivered during normal operation at full load. Therefore, indefinite over-current cycling does not create a thermal problem for the circuit. Summary The HIP6302EVAL1 is intended to provide a convenient platform to evaluate the performance of the HIP6302 HIP6601A chip set in the specific implementation indicated in Table 1. The design demonstrates a favorable trade off between low cost, high efficiency, and small footprint. The following pages include schematic, bill of materials, and layout drawings to facilitate implementation of this solution. The evaluation board is simple and convenient to operate, and test points are available to evaluate the most commonly tested parameters. Example waveforms are given for reference. The HIP6302 and HIP6601A provide a versatile 2-phase power solution for low-voltage applications from 25A to approximately 40A, and together they result in the most effective solution available. OUTPUT CURRENT, 20A/DIV References 0A For Intersil documents available on the internet, see web site http://www.intersil.com/ Intersil Technical Support 1 (888) INTERSIL CORE VOLTAGE, 500mV/DIV [1] HIP6302 Data Sheet, Intersil Corporation, Power Management Products Division, 2000. (http://www.intersil.com/). 0V [2] HIP6601A, HIP6603A Data Sheet, Intersil Corporation, Power Management Products Division, 2000. 5ms/DIV FIGURE 8. OVERCURRENT BEHAVIOR [3] HIP6602A Data Sheet, Intersil Corporation, Power Management Products Division, 2000. Efficiency Figure 9 shows the efficiency versus current plot for the HIP6302EVAL1 for 5A through 35A. The measurements were made at room temperature with natural convection cooling only.. 90 EFFICIENCY (%) 85 80 75 70 5 10 15 20 25 CURRENT (AMPERES) FIGURE 9. EFFICIENCY vs CURRENT 4 30 35 Application Note AN9888 Schematic 5VIN L1 1µF C6 1µF 12VIN 6 9 VCC PVCC 16 C7 0.1µF 7 VCC PWM1 GND 13 3 BOOT 1 UGATE HIP6601 1 2 3 4 5 VID4 VID3 ISEN1 VID2 14 4 U1 TP2 TP1 VID1 C9 1µF VID0 C12 1µF HIP6302 15 R1 2.15kΩ PGOOD PWM2 12 3 C10 100µF C2 1000µF C8 0.1µF 6 7 2 VCC PVCC JP1 C1 1000µF L2 450nH Q2 HUF76139 5 LGATE GND C5 100µF Q1 HUF76139 8 PWM PHASE TP3 C4 1µF C3 0.1µF 2 BOOT 1 UGATE PWM PHASE HIP6601 TP4 Q3 HUF76139 8 L3 450nH Q4 HUF76139 LGATE 5 GND TP6 4 U3 FS/DIS R3 107kΩ ISEN2 COMP FB VSEN 6 7 10 R4 14.0kΩ R5 1.00kΩ 11 TP5 R2 2.15kΩ TP7 C11 2.2nF C13-C17 22µF R6 45.3kΩ C18-C21 560µF JP2 HO R9 1kΩ RED U4 HIP2100 Q6 HUF76129 GREEN TP11 CR1 Q5 2N7002 R15 0.200Ω 3 R14, R16 0.100Ω POWER GOOD INDICATOR 4 HS 7 VSS LO 8 HI R7 1kΩ 6 LI Q7 HUF76129 R8 10kΩ 2 VDD 1 HB C48 1µF SW1 R17 46.4kΩ ON R18 400Ω Q8 2N7002 C49 10µF R12 R10 D1 BAV99 1.50kΩ D2 BAV99 1.50kΩ R13 R11 619Ω 619Ω TRANSIENT GENERATOR 5 OFF Application Note AN9888 Bill of Materials QTY REFERENCE DESCRIPTION 1 CR1 RED/GREEN LED 2 C1, C2 1000µF, 10V, Aluminum Capacitor 3 C3, C7, C8 0.1µF, 25V, Y5V, Ceramic Capacitor 5 C4, C6, C9, C12, C48 1.0µF, 25V, Y5V, Ceramic Capacitor 2 C5, C10 100µF, 16V, OS-CON Capacitor 1 C11 2.2nF, 50V, X7R, Ceramic Capacitor PACKAGE VENDOR PART NO. SMT Lumex SSL-LXA3025IGC Radial Panasonic EEUFC1A102L 0603 Various 0805 Various Radial Sanyo 0603 Various 5 C13-C17, C49 10µF, 10V, X7R, Ceramic Capacitor 1206 Various 4 C19, C20, C22, C23 560µF, 4V, OS-CON Capacitor Radial Sanyo 2 C18, C21 Spare Radial 24 C24-C47 Spare 1206 2 D1, D2 Dual Diode 1 JP1 5-Position Jumper Header JP2 1-Position Header 5 1 4SP560M SOT23 Various BAV99 100mil Centers Berg 68000-236 Berg 71363-102 100mil Centers Berg 68000-236 Berg 71363-102 Jumpers 1 16SPS100M Jumper 1 J1 ATX Power Header Berg 39-29-9203 2 J2, J3 Female Banana Connector, Red Johnson Components 111-0702-001 1 J4 Female Banana Connector, Black Johnson Components 111-0703-001 2 J5, J6 Terminal Connector Burndy KPA8CTP TTIG0803-127 1 L1 1uH, T30-26, 6T AWG18 400x300mil Falco 2 L2, L3 450nH, T60-8/90, 5T AWG14 700x500mil Falco TTIB1506-478 4 Q1, Q2, Q3, Q4 Power MOSFETs TO-263AB Intersil HUF76139S3S 2 Q5, Q8 General Purpose MOSFET SOT23 Various 2N7002 2 Q6, Q7 Power MOSFET TO-252AA Intersil HUF76129D3S 2 R1, R2 Resistor, 2.15kΩ, 1%, 1/10W 0603 Various 1 R3 Resistor, 107kΩ, 1%, 1/10W 0603 Various 1 R4 Resistor, 14.0kΩ, 1%, 1/10W 0603 Various 1 R5 Resistor, 1.00kΩ, 1%,1/10W 0603 Various Various 1 R6 Resistor, 45.3kΩ, 1%, 1/10W 0603 2 R7, R9 Resistor, 1.0kΩ, 5%, 1/8W 0805 Various 1 R8 Resistor, 10kΩ, 5%, 1/10W 0603 Various 2 R10, R12 Resistor, 1.50kΩ, 1%, 1/8W 0805 Various 2 R11, R13 Resistor, 619Ω, 1%, 1/8W 0805 Various 2 R14, R16 Resistor, 0.100Ω, 1%, 1W 2512 Vishay WSL2512R100FB43 1 R15 Resistor, 0.200Ω, 1%, 1W 2512 Vishay WSL2512R200FB43 Various 1 R17 Resistor, 46.4kΩ, 1%,1/8W 0805 1 R18 Resistor, 400Ω, 1%, 1/8W 0805 Various 1 SW1 Switch, SPDT SMT C&K Components GT11MSCKE 6 TP1, TP3, TP4, TP5, TP7, TP8 Small Test Point Jolo SPCJ-123-01 3 TP2, TP6, TP10 Keystone 1514-2 2 TP9, TP11 Probe Socket Tektronics 1314353-00 2 U1, U3 Synchronous Buck Driver IC 8-Lead SOIC Intersil HIP6601ACB 1 U2 Multiphase Buck Controller IC 16-Lead SOIC Intersil HIP6302CB 1 U4 MOSFET Driver IC 8-Lead SOIC Intersil HIP2100IB Large Test Point 6 Application Note AN9888 Layout Drawing - Components 7 Application Note AN9888 Layout Drawing - Top Copper 8 Application Note AN9888 Layout Drawing - Ground Plane 9 Application Note AN9888 Layout Drawing - Power Plane 10 Application Note AN9888 Layout Drawing - Bottom Copper All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems. Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality Intersil products are sold by description only. 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 data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries. For information regarding Intersil Corporation and its products, see www.intersil.com 11