PD-6.088 IRVRM2 1 Pentium II Power Supply Design Specification The new IRVRM2 offers the power supply designer a complete turnkey solution for DC/DC converters required to power Intel’s new Pentium II 1 microprocessor. A synchronous buck regulator topology operating at 200kHz is employed and achieves excellent efficiency with very fast transient load response and tight output voltage regulation. The new 20V low Vth HEXFET Power MOSFET D2Pak is used in the synchronous circuitry to reduce board temperature and assembly costs while improving circuit efficiency through reduced RDS(on). Complete performance characterization along with a detailed schematic, bill-of-materials, and PCB layout are offered to reduce the customer’s design time and effort. Purpose This is a production-ready design. It has been thoroughly tested for performance against the Intel Pentium II1 233/ 266MHz power specification, and evaluated for manufacturability by a high volume manufacturer. This design will not be manufactured by International Rectifier. Its purpose is to simplify the design and qualification process for our customers. Fig 1. IRVRM2 Key Features • Meets or exceeds all Intel 233/266MHz 1 Pentium II requirements • 12.7A continuous output • 1.8 to 3.5V digitally selectable output • 30A/µS transient load response capability • Short circuit protected • Surface Mount MOSFETs eliminate heatsinks • >80% Efficiency • Design kit available: IRVRM2 Web Site This design may be downloaded in two formats at IR’s web site (www.irf.com). One is PDF format for on screen viewing or printing, the other is in native format so that you many manufacture the design if desired. Floppy Disk The design is also available on floppy disk. As on our web site, the floppy version contains two formats, PDF and native format. Demo Boards Completed boards are available through your local IR sales office and distribution. Support E-mail Chris Davis at [email protected] for support of this design. Contents Specifications ------------------------------------- 2 Schematic Diagram ------------------------------- 3 Bill of Materials ----------------------------------- 4 Inductor Specifications --------------------------- 5 Assembly Options -------------------------------- 5 Static Performance ------------------------------- 6 Dynamic Performance ---------------------------- 6 Copyright Restriction This design may be used for production or evaluation purposes under the condition that all IR labeling and identification marks remain on all boards produced using this design, or as otherwise agreed to in writing by International Rectifier. 1 : A registered trademark of Intel Corporation © International Rectifier, 1997 International Rectifier Specifications IRVRM2 Absolute Maximum Ratings Parameter 5 volt input 12 volt input Continuous output current Ambient Temperature VID CODES (Table 2) (Table 1) Min 10 Max Units Conditions / Description 6.0 V 13.0 V 12.7 A Pulse width > 100ms 60 ºC Electrical Input Specifications Parameter 5 volt input (5Vin) 5 volt input current 12 volt input (12Vin) 12 volt input current Min 4.75 11.4 - Typ Max Units Conditions / Description 5.0 5.25 V Supply meet all output specifications 10 A All line and load conditions 12.0 13.0 V Supply meet all output specifications 40 60 mA All line and load conditions Power Output Specifications (all specified line and load conditions) Parameter Voltage Range Current Static Voltage regulation Transient Voltage Ripple voltage Turn on settling time Min 1.8 0 -2.1 -5 Typ 2.8 7.6 - -1 - 3.1 Max Units Conditions / Description 3.5 V Selected by VID[0:4] 12.7 A +3.6 % Of nominal VID set point. +5 % 30A/µs transitions 0.8A-to-12.7A @ 2.8V output +1 % Percent of nominal 10 mS Within ±10% of VID set point Digital Input / Output Specifications Signal PWRGD Input / Output output OUTEN input VID[0:4] input Conditions / Description Open collector output. Logic 1 output signifies that the voltage output of the module is within ±12% of the selected level Open collector input. Logic 0 disables the module output. Open collector input. Selects nominal output voltage as shown in table #2. Fig 2. Connector pin out Output Fault Protection Parameter Short circuit protection Over voltage protection Min Typ Max Units Conditions / Description 13 15.25 17.5 A Output current during short circuit or overload +10 +25 % Shuts down the power supply when the output voltage exceeds 10%-to25% above the set point Fig 3. Silkscreen top view Fig 4. Silkscreen bottom view IRVRM2 Schematic Diagram Fig 5. International Rectifier 3 Manufacturers International Rectifier -- (310) 322-3331 Novacap --------------------- (800) 227-2447 Panasonic ------------------- (800) 922-0028 Raytheon Electronics ----- (415) 968-9211 Rohm ------------------------- (408)433-2225 MMC ------------------------ (847) 577-0200 AMP ------------------------- (800) 522-6752 Sanyo ------------------------ (619) 661-6835 Dale Electronics ----------- (402) 563-6557 Bill of Materials PCB Fabrication Tedeum ----------------------- (909)946-4167 Distributors Digi-Key -------------------- (800) 344-4539 Garrett ----------------------- (800) 767-0081 Newark Electronics ------- (800) 463-9275 D.C. Electronics ------------ (408)947-4510 Marshall Electronics ----- (714) 842-3702 All American --------------- (818) 878-0533 (Table #3) Delivery Items used in this design were found to have production quantity lead times of under 10 weeks. Most were well under 8 weeks. Turn Key Manufacturing Golden West Techology ----- (714)738-3775 Inductor Winding Pacific Transformer ---------- (714) 779-0450 IRVRM2 International Rectifier 4 International Rectifier IRVRM2 Inductor Specifications Fig 6. IR001 Fig 7. IR002 Inductor Drawing The specified inductors IR001 and IR002 can be purchased, assembled and tested (see BOM). Assembly Options Q1 MOSFET Replacement It would be very rare for any design to Table 4 operate at 12.7A continuous output. All three Continuous current boundary @ Tj ≤ 115°C MOSFET options given in Table 4 will Q1 CURRENT operate at 12.7A continuous reliably. All IRVRM2a IRL3102S 11.92A three, however, will exceed the Intel IRVRM2b IRL3202S 11.66A recommended 115°C maximum junction IRVRM2c IRL3302S 11.48A temperature. A more useful comparison is using the Intel specified typical current on a continuous basis, and adding higher current demand on a pulsed basis. Figure 8 shows typical waveforms and junction temperature excursions. For a given “t1” pulse width and “d” duty factor, there is an “I1” current which will cause Q1 to reach the Intel recommended 115°C maximum. Fig 9. ≤ 115°C (IRL3302S) I1 current boundary @ Tj≤ Eliminate L2 Inductor L2 may be eliminated if your design does not require meeting the Intel recommended input di/dt specification, or if your design has additional external inductance. Figures 21, 22, 23, 25 shows the input di/dt both with and without L2. Fig 8. Typical load current and T j waveform Perfomance using MOSFET replacement Figures 9 thru 11 show that in most practical cases the less expensive IRL3302S would be the device of choice. Test conditions shown on Figure 8. Fig 10. I1 current boundary @ Tj ≤ 115°C ( IRL3202S) Fig 11. ≤ 115°C ( IRL3102S) I1 current boundary @ Tj≤ 5 International Rectifier IRVRM2 Static Performance Efficiency Efficiency is required to be at least 80% at full load. Thanks to the very efficient 20V low Vth MOSFETs, IRVRM2 exceeds the required specification by a comfortable margin. Maximum Junction Temperature Analysis of Q1 junction temperature shows that it remains within specifications at an ambient temperature of 50°C, even in still air. Fig 12. Typical Efficiency Fig 13. Typical Tj of Q1 T a = 25ºC (still air) Fig 14. Projected Tj of Q1 Ta = 50ºC (still air) Fig 15. Typical Load Regulation Load Regulation The output must stay within its -2.1% ~ +3.6% static specification from no load to full load. Fig 16. Typical Line Regulation Line Regulation The Intel specification requires the line voltage to be within ±5% of nominal voltage. IRVRM2 easily meets line regulation specification even up to ±10%. Dynamic Performance Fig 17. Transient Load Current Rise Time Transient Load Test Conditions The Intel specification requires the supply to stay within its ±5% specification during transient load event of 0.8A-to-12.7A at a rate of 30A/µs. Although most motherboards do not require this full level of performance, IRVRM2 meets the full transient response specification. Fig 18. Transient Load Current Fall time 6 International Rectifier IRVRM2 Dynamic Performance (continued) Fig 19. 100 Hz Transient Output Voltage Transient Load At VRM2 Performance at 100kHz is dominated by stray output inductance and resistance. These are a combination of output capacitor ESL & ESR and board + connector inductance & resistance. Performance at 100Hz exhibits the same rise & fall characteristics as at 100kHz. Setting the oscilloscope so as to see the whole waveform, however, reveals any undersirable loop characteristics. As shown, IRVRM2 is very well behaved at both 100Hz and 100kHz. Min Max Fig 21. Rising Input Current Waveform Limit 2.66V 2.94V Fig 20. 100 kHz Transient Output Voltage 100Hz 100kHz 2.706 2.670 2.842 2.834 Input di/dt During Transient Load Intel’s specification recommends a maximum input di/dt during transient load of 0.1A/µs. IRVRM2 readily meets this specification at rising and falling edges of input current. Fig 22. Falling Input Current Waveform Transient measurements were taken with 1µH of total line inductance between the input power supply and IRVRM2. This approximately simulates total path inductance from the silver box to the VRM board in a typical computer system. IRVRM2 has an input inductance of 0.5µH (L2) to limit input di/dt to the Intel recommended 0.1A/µs. Fig 23. Rising Input current without L2 Fig 24. Input di/dt Test Circuit L2 = 0.5µH L2 = 0.0µH Limit .1A/µs .1A/µs Fig 25. Falling Input Current without L2 Rising Falling 0.074 0.087 0.09 0.108 7 International Rectifier IRVRM2 Dynamic Performance (continued) Fig 26. Output Voltage Ripple (No Load) Output Ripple Voltage Output ripple voltage is specified as a ±1% range, (56mV peak-to-peak) of the nominal output voltage. Parameter P-P ripple Fig 28. Turn on Waveform (Full Load) Limit 56mV Measured 15.2mV Turn On Transient Output voltage must remain within 10% of the nominal set point. Also, output voltage should reach its specified range, -2.1% ~ +3.6%, within 10ms after input voltage reaches 95% of nominal voltage. Parameter Risetime Overshoot Limit 10ms 3.08V Fig 27. Output Voltage Ripple (Full Load) Fig 29. Turn off Waveform (Full Load) Measured 3.1ms 2.82V WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, Tel: (310) 322 3331 EUROPEAN HEADQUARTERS: Hurst Green, Oxted, Surrey RH8 9BB, UK Tel: ++ 44 1883 732020 IR CANADA: 15 Lincoln Court, Brampton, Ontario L6T 3Z2, Tel: (905) 453 2200 IR GERMANY: Saalburgstrasse 157, 61350 Bad Homburg Tel: ++ 49 6172 96590 IR ITALY: Via Liguria 49, 10071 Borgaro, Torino Tel: ++ 39 11 451 0111 IR FAR EAST: K&H Bldg., 2F, 3-30-4 Nishi-Ikebukuro, Toshima-ku, Tokyo 171 Japan Tel: 81 3 3983 0641 IR SOUTHEAST ASIA: 315 Outram Road, #10-02 Tan Boon Liat Building, Singapore 0316 Tel: 65 221 8371 http://www.irf.com/ Data and specifications subject to change without notice. 9/97