TM AMD-K5™ PROCESSOR Support for the AMD-K5 Dual Voltage Processor Application Note Publication # 19766 Rev: C Issue Date: September 1996 Amendment/0 This document contains information on a product under development at Advanced Micro Devices (AMD). The information is intended to help you evaluate this product. AMD reserves the right to change or discontinue work on this proposed product without notice. © 1996 Advanced Micro Devices, Inc. All rights reserved. Advanced Micro Devices reserves the right to make changes in its products without notice in order to improve design or performance characteristics. This publication neither states nor implies any representations or warranties of any kind, including but not limited to any implied warranty of merchantability or fitness for a particular purpose. AMD makes no representations or warranties with respect to the accuracy or completeness of the contents of this publication or the information contained herein, and reserves the right to make changes at any time, without notice. AMD disclaims responsibility for any consequences resulting from the use of the information included herein. Trademarks AMD, the AMD logo, and combinations thereof are trademarks of Advanced Micro Devices, Inc. AMD-K5 is a trademark of Advanced Micro Devices, Inc. Other product names used in this publication are for identification purposes only and may be trademarks of their respective companies. 19766C/0—Sep1996 Support for the AMD-K5 Dual Voltage Processor Contents Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Dual Voltage Processor Power Supply Specification . . . . . . . . . . . . . 3 Voltage Planes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Current Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Dual Voltage Power Supply Circuits. . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Low Cost Dual Voltage Power Supply Circuit . . . . . . . . . . . . . . . . . . . 6 Precision Dual Voltage Power Supply Circuit . . . . . . . . . . . . . . . . . . . 8 Printed Circuit Layout Recommendations . . . . . . . . . . . . . . . . . . . . . 10 Component Notes and Noise Reduction . . . . . . . . . . . . . . . . . . . . . . . 11 Linear Regulator Integrated Circuits . . . . . . . . . . . . . . . . . . . . . . . . . 11 Power Supply Decoupling Capacitors . . . . . . . . . . . . . . . . . . . . . . . . . 11 Processor Decoupling Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Component Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Split Voltage Plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Additional Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Contents iii Support for the AMD-K5 Dual Voltage Processor iv 19766C/0—Sep1996 Contents Support for the AMD-K5 Dual Voltage Processor 19766C/0—Sep1996 List of Tables Table 1. Table 2. Table 3. Table 4. Table 5. Core Voltage Requirements . . . . . . . . . . . . . . . . . . . . . . . . 5 Jumper Settings for the Low Cost and Precision Dual Voltage Power Supply Circuits . . . . . . . . . . . . . . . . . 6 Bill of Materials for the Low Cost Dual Voltage Power Supply Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Bill of Materials for Precision Dual Voltage Power Supply Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Additional Information for AMD-K5 Dual Voltage Processors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 List of Figures Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Package Marking for the AMD-K5 Processor (Model 0) . 2 Package Marking for the AMD-K5 Processor (Model 1) . 2 Location of Vcc and Ground Pins in the SPGA Package . 4 Low Cost Dual Voltage Power Supply Circuit. . . . . . . . . . 7 Precision Dual Voltage Power Supply Circuit . . . . . . . . . 9 Suggested Component Placement for the Low Cost Dual Voltage Circuit . . . . . . . . . . . . . . . . . . . . . 13 Figure 7. Suggested Component Placement for the Precision Dual Voltage Circuit . . . . . . . . . . . . . . . . . . . . . 14 List of Tables and Figures v Support for the AMD-K5 Dual Voltage Processor vi 19766C/0—Sep1996 List of Tables and Figures 19766C/0—Sep1996 Support for the AMD-K5 Dual Voltage Processor Support for the AMD-K5™ Dual Voltage Processor AMD-K5™ processors, manufactured with AMD’s enhanced 0.35-µm process (CS34E), require a lower supply voltage for the core, separate from that used to power the I/O pins (3.38 V or 3.52 V). Dual voltage processors can be identified by an H, J, or K in the operating voltage suffix of the ordering part number (OPN). See Figure 1 for more details. This application note describes two dual voltage regulator circuits that can be used to generate a 3.38-V or 3.52-V I/O voltage supply and a selectable core supply voltage (2.50 V, 2.70 V, 2.93 V, 3.38 V, or 3.52 V) from a standard personal computer power supply. In addition, specific recommendations are given for decoupling capacitor selection and placement to achieve optimal noise reduction levels. Background As digital integrated circuit manufacturing processes advance, finer geometries require lower supply voltages to operate properly. Processors manufactured with the CS34E process will use a reduced voltage between 2.50 V and 2.93 V to power the core circuitry of the processor. Specially designed circuits for the I/O buffers will operate with a separate voltage supply of 3.38 V or 3.52 V to accommodate standard logic and memory devices connected to the bus. Background 1 Support for the AMD-K5 Dual Voltage Processor 19766C/0—Sep1996 AMD has developed two linear dual voltage regulator circuits, each of which can be used to generate a 3.38-V or 3.52-V supply for the I/O and a core voltage supply of 2.50 V, 2.70 V, or 2.93 V, selectable via jumpers on the motherboard. These circuits also support single voltage versions of the AMD-K5 processor. A basic issue in power supply circuit design is noise reduction. Excessive noise levels can impair proper operation and contribute to possible EMI and RFI radiation. This application note provides some basic guidelines for reducing noise generated by fast transients of voltage and current wave forms. Product Name Package Type: A = SPGA P-Rating Processor Core OPN !-$+TM PR100 AMD-K5-PR100ABQ 100 MHz E <DATECODE> m c 1996 AMD HEATSINK AND FAN Operating Voltage: B = 3.45 V–3.60 V (3.52 V Nominal) H = 2.86 V–3.0 V Core/3.135 V–3.465 V I/O (2.93 V Nominal Core/3.30 V Nominal I/O Case Temperature: Q = 60°C R = 70°C Internal CPU Frequency Figure 1. Package Marking for the AMD-K5 Processor (Model 0) Product Name Package Type: A = SPGA P-Rating Processor Core OPN !-$+TM PR133 AMD-K5-PR133ABQ B <DATECODE> m c 1996 AMD Operating Voltage: B = 3.45 V–3.60 V (3.52 V Nominal) H = 2.86 V–3.0 V Core/3.135 V–3.465 V I/O (2.93 V Nominal Core/3.30 V Nominal I/O 66 MHz Bus 3.52 V Bus Frequency Nominal Voltage HEATSINK AND FAN Case Temperature: Q = 60°C R = 70°C Figure 2. Package Marking for the AMD-K5 Processor (Model 1) 2 Support for the AMD-K5™ Dual Voltage Processor 19766C/0—Sep1996 Dual Voltage Processor Power Supply Specification Voltage Planes The AMD-K5 dual voltage processor has internal voltage planes for core and I/O. The power supply Vcc pin assignments for the AMD-K5 processor are as follows: VCC2 (Core): A-07, A-09, A-11, A-13, A-15, A-17, G-01, J-01, L-01, N-01, Q-01, S-01, U-01, W-01, Y-01, AA-01, AC-01, AE-01, AG-01, AN-09, AN-11, AN-13, AN-15, AN-17, AN-19 VCC3 (I/O): A-19, A-21, A-23, A-25, A-27, A-29, E-37, G-37, J-37, L-33, L-37, N-37, Q-37, S-37, T-34, U-33, U-37, W-37, Y-37, AA-37, AC-37, AE-37, AG-37, AN-21, AN-23, AN-25, AN-27, AN-29 INC: AN-01, AN-03 Notes: 1) Some motherboards connect a 5 V supply to pins AN-01 and AN-03. This connection is not required for the AMD-K5 processor and these pins are internally not connected (INC). 2) The voltage select pin (VCC2DET) active Low is located at AL-01. Figure 3 shows the location of the separate Vcc and ground pins on the SPGA package. Dual Voltage Processor Power Supply Specification 3 Support for the AMD-K5 Dual Voltage Processor 19766C/0—Sep1996 VCC2 pins (core) VCC3 pins (I/O) Other VSS pins INC pins (see Note on page 3) VCC2DET pin Figure 3. Location of Vcc and Ground Pins in the SPGA Package 4 Support for the AMD-K5™ Dual Voltage Processor 19766C/0—Sep1996 Current Requirements The AMD-K5 dual voltage processor has the following maximum current requirements (rated at maximum Tcase and maximum Vcc2 and Vcc3): Maximum Icc core of 27 mA / MHz ■ Maximum Icc I/O of 16 mA / MHz Note: This information is preliminary and subject to change. See the AMD-K5™ Processor Data Sheet (order# 18522) for the latest information. ■ The core voltage requirements are shown in Table 1. The table identifies the dual voltage processors by their operating voltage suffixes H (2.93 V), J (2.70 V), and K (2.50 V). See Figure 1 for more information. Table 1. Core Voltage Requirements Core Vcc (OPN Suffix) Minimum Center Maximum H 2.860 V 2.930 V 3.000 V J 2.565 V 2.700 V 2.835 V K 2.375 V 2.500 V 2.625 V Dual Voltage Power Supply Circuits Two dual voltage supply circuits have been developed for use with the AMD-K5 processor. Both designs support single and dual voltage versions of the AMD-K5 processor. The designs are as follows: ■ ■ Low Cost Dual Voltage Power Supply Circuit This circuit meets all the current and voltage requirements for the AMD-K5 processor while minimizing costs. See “Low Cost Dual Voltage Power Supply Circuit” on page 6 for more information. Precision Dual Voltage Power Supply Circuit This circuit uses five-terminal, high-precision regulators that provide tighter regulation and improved design margin for more demanding applications. See “Precision Dual Voltage Power Supply Circuit” on page 8 for more information. Dual Voltage Power Supply Circuits 5 Support for the AMD-K5 Dual Voltage Processor 19766C/0—Sep1996 Low Cost Dual Voltage Power Supply Circuit The circuit diagram for the low cost dual voltage power supply is shown in Figure 4. Regulator U1 provides a 3.38 V or 3.52 V supply to the processor I/O. Jumper J4 selects the voltage level to power the I/O circuitry. When J4 is installed, Vcc3 will be 3.38 V ± 2%. When J4 is not installed, Vcc3 will be 3.53 V ± 2%. Regulator U2 provides a variable supply of 2.50 V, 2.70 V, or 2.93 V to the processor core. The supply voltage is selectable via jumpers J3, J2, and J1, respectively. Jumpers J5 through J8 should be installed when using single voltage versions of the AMD-K5 processor. The jumpers connect the output of regulator U1 (I/O voltage) to the output of regulator U2 (core voltage), providing a common voltage (3.38 V or 3.52 V) to both the I/O and core of the processor. Regulator U2 senses the presence of a higher voltage on its output pin and safely shuts off its output circuitry. This is an acceptable configuration and does not harm either regulator. Using example OPNs, Table 2 shows the appropriate jumper settings for each voltage option. Table 2. Jumper Settings for the Low Cost and Precision Dual Voltage Power Supply Circuits Jumpers Installed Example OPN Vcc2 (Core) Vcc3 (I/O) J1 J2 J3 J4 J5 – J8 AMD-K5-PR90AHQ 2.93 V 3.38 V X — — X — AMD-K5-PR90AJQ 2.70 V 3.38 V — X — X — AMD-K5-PR90AKQ 2.50 V 3.38 V — — X X — AMD-K5-PR90ACQ1 3.38 V 3.38 V — — — X X AMD-K5-PR90ABQ1 3.53 V 3.53 V — — — — X Notes: 1. Single-voltage mode only. X Installed — Not installed 6 Support for the AMD-K5™ Dual Voltage Processor 19766C/0—Sep1996 Figure 4. Low Cost Dual Voltage Power Supply Circuit Note: Jumper J1 is shorted by a trace and is therefore not required. The J1 jumper header, if installed, can serve as a resting spot for a jumper when it is not installed at the J2 or J3 header. Low Cost Dual Voltage Power Supply Circuit 7 Support for the AMD-K5 Dual Voltage Processor 19766C/0—Sep1996 Precision Dual Voltage Power Supply Circuit The circuit diagram for the precision dual voltage power supply is shown in Figure 5. Regulator U1 provides a 3.38-V or 3.53-V supply to the processor I/O, selectable via jumper J4. Regulator U2 provides a variable supply (2.50 V, 2.70 V, or 2.93 V) to the processor core, selectable via jumpers J3, J2, and J1. Five-terminal voltage regulators (model 1580) provide tighter regulation, adding design margin for applications that may experience extremes in temperature and/or AC line regulation. The precision circuit has the following advantages relative to the low cost circuit: ■ ■ ■ ■ ■ Improved output voltage regulation due to the use of a 12-V input reference voltage Improved tolerance to changes in line, load, and temperature Greater ripple rejection Lower dropout voltage Greater maximum load current (The voltage regulators used in the precision circuit can supply 7.0 amps of current per regulator. The voltage regulators used in the low cost circuit can supply 4.6 amps of current per regulator.) See the data sheets for the voltage regulators for the latest specifications. Using example OPNs, Table 2 shows the appropriate jumper settings for each voltage option. 8 Support for the AMD-K5™ Dual Voltage Processor 19766C/0—Sep1996 Figure 5. Precision Dual Voltage Power Supply Circuit Note: Jumper J1 is shorted by a trace and is therefore not required. The J1 jumper header, if installed, can serve as a resting spot for a jumper when it is not installed at the J2 or J3 header. Precision Dual Voltage Power Supply Circuit 9 Support for the AMD-K5 Dual Voltage Processor 19766C/0—Sep1996 Printed Circuit Layout Recommendations Printed circuit layout recommendations for the AMD-K5 processor dual voltage power supply circuit include the following: 1. Use a multiple-plane motherboard. The preferred sequencing of signal, power, and ground planes (assuming a six-layer printed circuit board) are as follows: Layer 1: Layer 2: Layer 3: Layer 4: Layer 5: Layer 6: Signal 1 Ground Signal 2 Signal 3 Power Signal 4 2. Some of the processor data bus I/O pins are located within the suggested core Vcc plane area (see Figures 6 and 7). Traces for these pins should be restricted to signal layers 1, 2, and 3 (avoid signal 4) to ensure a low-impedance path for return currents. 3. Use 0.01 µF MLC capacitors (e.g., AVX 0805YA103MAT2A) to connect the I/O Vcc plane with the core Vcc plane, locating these capacitors near any trace with fast edge rate signals. These capacitors provide a low-impedance return path for high-frequency currents. 4. Use multiple vias when connecting voltage regulators and large capacitors (greater than 200 µF) to power and ground planes. 5. Use minimum copper lead lengths, wherever possible, to reduce inductance and resistance. 6. Use correct component orientation, wherever possible, to minimize lead lengths. 7. Where possible, use a top-level trace to connect decoupling capacitors to the processor’s Vcc and ground pins. 8. When printed circuit layout permits, some bypass capacitors should be located on the outside edge of the processor socket. These capacitors should be positioned to permit direct top-side routing to the processor Vcc and ground pins. 10 Support for the AMD-K5™ Dual Voltage Processor 19766C/0—Sep1996 Component Notes and Noise Reduction Linear Regulator Integrated Circuits The linear three-terminal voltage regulators, U1 and U2, both require input decoupling capacitors and output bulk decoupling tantalum capacitors with low ESR values (e.g., less than 100 mΩ). Heat sinks for the TO220 packages required for both linear regulator circuits are dependent on mechanical size restrictions of the design and the ambient air temperature specification inside the personal computer enclosure. Both linear regulators should have low dropout voltages (approximately one volt) required when the input voltage is 5 V (± 5%). Power Supply Decoupling Capacitors The input capacitors C1, C2, and C3 function as decoupling capacitors for the 5 V input power from the personal computer power supply. C5 and C6 provide bulk capacitance at low ESR (equivalent series resistance) and ESL (equivalent series inductance). C8 to C38 keep the ESR and ESL Low at high frequencies (greater than 100 kHz) because of the multiple parallel current paths. Surface mounted capacitors with large lead widths are recommended to reduce lead inductance and resistance. The output capacitors are required by the linear regulator circuits to minimize ringing during damping periods and to supply transient current requirements during processor clock edges when maximum peak current occurs. Surface mounted capacitors are recommended to reduce lead lengths. Processor Decoupling Capacitance The processor decoupling capacitors (C8 to C42) should be located as close to the processor Vcc ground pins as possible. It is recommended that surface mounted capacitors be used to minimize resistance and inductance in the lead lengths. When possible, use traces to connect capacitors directly to the processor’s Vcc and ground pins. Component Notes and Noise Reduction 11 Support for the AMD-K5 Dual Voltage Processor 19766C/0—Sep1996 Component Layout A suggested component placement for the low cost dual voltage power supply circuit is shown in Figure 6. Table 3 is a bill of materials for the low cost circuit. A suggested component placement for the precision dual voltage power supply circuit is shown in Figure 7. Table 4 is a bill of materials for the precision circuit. Split Voltage Plane AMD recommends using a split voltage plane to supply separate voltages to the I/O and core of the processor. This approach helps reduce noise levels without requiring the need for additional printed circuit board layers. Figures 6 and 7 show examples of suggested component placement for the two circuits. The solid line on each figure represents the approximate location for separation of the voltage power planes. Components have been placed in accordance with their associated voltage plane. Jumpers J5 through J8 straddle the planes and connect the planes together when installed. An isolation region (2 mm minimum is recommended) should separate the two voltage planes. Note: The ground plane should never be split; it provides a low impedance current sink and reference. 12 Support for the AMD-K5™ Dual Voltage Processor 19766C/0—Sep1996 Isolation region (2 mm recommended) Figure 6. Suggested Component Placement for the Low Cost Dual Voltage Circuit Component Notes and Noise Reduction 13 Support for the AMD-K5 Dual Voltage Processor 19766C/0—Sep1996 Isolation region (2 mm recommended) Figure 7. Suggested Component Placement for the Precision Dual Voltage Circuit 14 Support for the AMD-K5™ Dual Voltage Processor 19766C/0—Sep1996 Table 3. Bill of Materials for the Low Cost Dual Voltage Power Supply Circuit Item Qty. Reference No. Value Footprint 1 1 R1 110 Ω, 1%, 1/8 Watt 0805 Resistor, surface mount 2 1 R2 12.4 Ω, 1%, 1/8 Watt 0805 Resistor, surface mount 3 1 R3 187 Ω, 1%, 1/8 Watt 0805 Resistor, surface mount 4 1 R4 107 Ω, 1%, 1/8 Watt 0805 Resistor, surface mount 5 1 R5 143 Ω, 1%, 1/8 Watt 0805 Resistor, surface mount 6 1 R6 931 Ω, 1%, 1/8 Watt 0805 Resistor, surface mount 7 1 R7 432 Ω, 1%, 1/8 Watt 0805 Resistor, surface mount 8 9 C1, C2, C3, C5, 330 µF, 6.3 V, C6, C39–C42 20% AVX Size E Capacitor, surface mount, tantalum, AVX part no. TPSE337M063100 or equivalent 9 2 C4, C7 0.33 µF, 16 V, 20% 0805 Capacitor, surface mount, ceramic, AVX (Y5V Dielectric) part no. 012063G334ZAT2A or equivalent 10 31 C8–C22 and C23–C38 0.1 µF 0805 Capacitor, surface mount, ceramic, AVX (X7R Dielectric) part no. 0805YC104MAT2A or equivalent 11 2 U1, U2 LT1585 or EZ1585 TO220 Linear regulator, 3 terminal (5 amp) (Linear Technology or Semtech) Description 12 1 HS Heat Sink Heat Sink Heat sink can be thermally connected to both U1 and U2, but is electrically isolated via mica insulators or Thermalloy TO220 heat sink (size depends on printed circuit layout and ambient temperature specification for personal computer) (e.g., Thermalloy 7020B-MT) 13 8 J1–J8 Berg Header 2 Pin TH Headers, 2 pin, through hole, 0.1 in spacing Component Notes and Noise Reduction 15 Support for the AMD-K5 Dual Voltage Processor Table 4. 19766C/0—Sep1996 Bill of Materials for Precision Dual Voltage Power Supply Circuit Item Qty. Reference No. Value Footprint 1 1 R1 110 kΩ, 1%, 1/8 Watt 0805 Resistor, surface mount 2 1 R2 12.4 Ω, 1%, 1/8 Watt 0805 Resistor, surface mount 3 1 R3 187 Ω, 1%, 1/8 Watt 0805 Resistor, surface mount 4 1 R4 107 Ω, 1%, 1/8 Watt 0805 Resistor, surface mount 5 1 R5 143 Ω, 1%, 1/8 Watt 0805 Resistor, surface mount 6 1 R6 931 Ω, 1%, 1/8 Watt 0805 Resistor, surface mount 7 1 R7 432 Ω, 1%, 1/8 Watt 0805 Resistor, surface mount 8 1 R8, R9 2 Ω, 5%, 1/8 Watt 0805 Resistor, surface mount 9 9 10 2 C4, C7 0.33 µF, 16 V, 20% 0805 Capacitor, surface mount, ceramic, AVX (Y5V Dielectric) part no. 012063G334ZAT2A or equivalent 11 31 C8–C22 and C23–C38 0.1 µF 0805 Capacitor, surface mount, ceramic, AVX (X7R Dielectric) part no. 0805YC104MAT2A or equivalent 12 2 C43, C44 1 µF, 16 V 20% 1210 Capacitor, surface mount, ceramic, AVX (Y5V Dielectric) part no. 012063G105ZAT2A or equivalent 13 1 C45 33 µF, 20 V AVX Size D 14 2 U1, U2 LT1580 or EZ1580 TO220 16 C1, C2, C3, C5, 330 µF, 6.3 V, C6, C39–C42 20% AVX Size E Description Capacitor, surface mount, tantalum, AVX part no. TPSE337M063100 or equivalent Capacitor, surface mount, tantalum, AVX part no. TPSD336M020R0200 or equivalent Linear regulator, 5 terminal (7 amp) (Linear Technology or Semtech) 15 1 HS Heat Sink Heat Sink Heat sink can be thermally connected to both U1 and U2, but is electrically isolated via mica insulators or Thermalloy TO220 heat sink (size depends on printed circuit layout and ambient temperature specification for personal computer) (e.g., Thermalloy 7020B-MT) 16 8 J1–J8 Berg Header 2 Pin TH Headers, 2 pin, through hole, 0.1 in spacing Support for the AMD-K5™ Dual Voltage Processor 19766C/0—Sep1996 Additional Information The following third-party application notes provide information about products designed to accommodate AMD-K5 dual voltage processors. Table 5. Additional Information for AMD-K5 Dual Voltage Processors Title Power Solutions for the AMD-K5™ Microprocessor Order Number AN96-1 Available From: Semtech Corporation 652 Mitchell Road Newbury Park, CA 91320 Attention: Andrew Stewart Tel: 805-498-2111 Fax: 805-498-3804 Power Solutions for the AMD-K5™ Processors Application Note 133 Linear Technology Corporation 1630 McCarthy Blvd. Milpitas, CA 95035-7487 Attention: Craig Varga Tel: 408-432-1900 Fax: 408-434-0507 Additional Information 17 Support for the AMD-K5 Dual Voltage Processor 18 19766C/0—Sep1996 Support for the AMD-K5™ Dual Voltage Processor