19-1268; Rev 2; 12/00 MAX1636 CPU Supply Evaluation Kit ____________________________Features ♦ +7V to +22V Input Voltage Range ♦ Digitally Adjustable 1.25V to 2V Output Voltage ♦ 7A Output Current Capability ♦ ±1% DC Output Accuracy ♦ Efficiency = 87%, VIN = 7V, VOUT = 1.7V (at IOUT = 3A) ♦ Fast MOSFETs for Low Switching Losses ♦ Tight PC Board Layout for Low Switching Losses ♦ Power-Good Output ♦ 300kHz Switching Frequency ♦ Overvoltage and Undervoltage Protection ♦ Surface-Mount Construction ♦ Fully Assembled and Tested Ordering Information PART TEMP. RANGE MAX1636CPUEVKIT 0°C to +70°C IC PACKAGE 20 SSOP Component List DESIGNATION QTY DESCRIPTION C1, C2, C3, C4 4 10µF, 25V ceramic capacitors Tokin C34Y5U1E106Z or United Chemicon/Marcon THCR50E1E106ZT C5, C7, C8, C9, C10 5 0.1µF ceramic capacitors C11 1 1500pF ceramic capacitor C12 1 1µF ceramic capacitor C13 1 4.7µF, 16V tantalum capacitor Sprague 595D475X0016A2B C14, C15, C16 3 470µF, 6.3V, 30mΩ low-ESR tantalum capacitors Kemet T510X477M006 or 470µF, 4V, 470µF, 55mΩ low-ESR tantalum low-ESR4V, tantalum capacitors caps Sprague 594D477X0004R2T Sprague 594D477X0004R2T C14, C15, C16, C17 4 C18 0 Open 1 Schottky diode SGS-Thomson STPS2L25U, International Rectifier 10BQ040, or Motorola MBRS130LT3 D1 D2 1 Schottky diode Central Semiconductor CMPSH-3 DESIGNATION QTY DESCRIPTION 1 2.2µH power inductor Panasonic P1F2R0HL, Coiltronics UP4-2R2, or Coilcraft DO5022P-222HC 1 N-channel MOSFET Fairchild FDS9412, International Rectifier IRF7803, or Siliconix Si9804DY N2 1 N-channel MOSFET Fairchild FDS6680, International Rectifier IRF7801, or Siliconix Si4420DY R1 1 0.010Ω, 1%, 1W resistor Dale WSL-2512-R010F R2 1 10kΩ, 0.1% resistor Dale TNPW-1206 series R3 1 110kΩ, 0.1% resistor Dale TNPW-1206 series R4 1 13.7kΩ, 0.1% resistor Dale TNPW-1206 series R5 1 51Ω, 5% resistor R6, R15 2 100kΩ, 5% resistors L1 N1 ________________________________________________________________ Maxim Integrated Products 1 For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. Evaluates: MAX1636 General Description The MAX1636 CPU supply evaluation kit (EV kit) circuit is intended for converting high-voltage battery power into a low-voltage supply rail for next-generation notebook CPU cores. The output is digitally adjustable between 1.25V and 2V, in 50mV increments. The input range is +7V to +22V. It delivers up to 7A output current with greater than 87% efficiency. The MAX1636 features ±1% DC output accuracy over all conditions of line, load, and temperature. The fully assembled and tested EV kit has excellent dynamic response to correct for fast load transients. This EV kit is very specific to notebook CPU core power supplies, and includes a digital-to-analog converter (DAC), op-amp buffer, and other high-performance components tailored to this demanding application. However, the MAX1636 is a general-purpose, standalone device that can be used without the DAC; see the MAX1636 data sheet for standard application circuits. Evaluates: MAX1636 MAX1636 CPU Supply Evaluation Kit Component List (continued) DESIGNATION QTY R7 1 20Ω, 5% resistor DESCRIPTION R8–R12, R14, R15, R16 8 1MΩ, 5% resistors SW1 1 Four-position dip switch U1 1 MAX1636EAP (20-pin SSOP) U2 1 MAX5480BEEE (16-pin QSOP) U3 1 MAX4332ESA (8-pin SO) or MAX4163ESA (alternate type with lower supply current but slightly degraded accuracy) None 1 MAX1636 PC board None 1 MAX1636 data sheet JU3, JU4, JU5 3 2-pin header Quick Start The MAX1636 EV kit is fully assembled and tested. Follow these steps to verify board operation. Do not turn on the power supply until all connections are completed. 1) Connect a +7V to +22V supply voltage to the VIN pad. Connect ground to the GND pad. 2) Connect a voltmeter and load, if any, to the VOUT pad. 3) Turn on the power supply to the board. Verify that the output voltage is 2V (SW1 set to all zeros). 4) Set switch SW1 per Table 1 to get the desired output voltage. Input power may need to be cycled off and on for new voltage settings to take effect. Table 1. Output Voltage Settings Component Supplier SUPPLIER PHONE FAX D3 D2 D1 D0 VOUT (V) 0 0 0 0 2.00 AVX (803) 946-0690 (803) 626-3123 0 0 0 1 1.95 Central Semiconductor (516) 435-1110 (516) 435-1824 0 0 1 0 1.90 Coilcraft (847) 639-6400 (847) 639-1469 0 0 1 1 1.85 Dale-Vishay (402) 564-3131 (402) 563-6418 0 1 0 0 1.80 Fairchild (408) 721-2181 (408) 721-1635 0 1 0 1 1.75 International Rectifier 0 1 1 0 1.70 (310) 322-3331 (310) 322-3332 0 1 1 1 1.65 IRC (512) 992-7900 (512) 992-3377 1 0 0 0 1.60 Kemet (864) 963-6300 (864) 963-6521 1 0 0 1 1.55 Motorola (602) 303-5454 (602) 994-6430 1 0 1 0 1.50 Panasonic (201) 348-7522 (201) 392-4441 Sanyo (619) 661-6835 (619) 661-1055 1 0 1 1 1.45 SGS-Thomson (617) 259-0300 (617) 259-9442 1 1 0 0 1.40 1 0 1 1.35 Siliconix (408) 988-8000 (408) 970-3950 1 Sprague (603) 224-1961 (603) 224-1430 1 1 1 0 1.30 Sumida (847) 956-0666 (847) 956-0702 1 1 1 1 1.25 Tokin (408) 432-8020 (408) 434-0375 Vishay/Vitramon (203) 268-6261 (203) 452-5670 Note: Please indicate that you are using the MAX1636 when contacting these component suppliers. 2 _______________________________________________________________________________________ MAX1636 CPU Supply Evaluation Kit Table 2. Jumper JU2 Functions SHUNT LOCATION MAX1636 SKIP PIN Off Connected to GND Idle mode, pulse-skipping operation for highest lightload efficiency On Connected to VCC Low-noise mode, fixed-frequency PWM operation. OPERATING MODE The 2-pin header JU3 selects the operating frequency. Table 3 lists the selectable jumper options. The EV kit’s components are selected for 300kHz operation. Component values might need to be changed if 200kHz operation is selected (refer to the Design Procedure section in the MAX1636 data sheet). Synchronize the oscillator to an external clock signal by driving the SYNC pad with a 5V amplitude pulse train in the 240kHz to 350kHz frequency range. Table 3. Jumper JU3 Functions SHUNT LOCATION MAX1636 SYNC PIN FREQUENCY (kHz) Off Connected to VCC 300 On Connected to GND 200 Table 4. Jumper JU4 and JU5 Selection JU4 JU5 OVP PIN TIED TO Off Off VCC VIN RUN mode, OVP enabled Off On VCC GND Standby mode, VL output alive On Off GND VIN RUN mode, OVP disabled On On GND GND Total shutdown mode SHUNT LOCATIONS SHDN PIN TIED TO RESULT Latched Fault Protection The MAX1636 contains a latched fault-protection circuit that disables the IC when the output is overvoltage or undervoltage (or when thermal shutdown is triggered). Once disabled, the supply won’t attempt to restart until input power is cycled or until SHDN (JU5) is cycled. A fault condition can be triggered by overloading the output, overvoltaging the output (which can happen when changing the D/A code settings), or by touching sensitive compensation or feedback nodes. Optional +5V Chip-Supply Input An optional +5V supply input (Figure 1) can power the IC and gate drivers to improve efficiency. The idea is to power the IC from an efficient source (the +5V system supply, typically 95% efficient) instead of relying on the inefficient internal VL linear regulator. To test this feature, cut the trace at V+ and connect V+ to VL to disable the linear regulator, and connect an external +5V, 50mA supply to the optional input. Alternate Op Amp for Lower Supply Current The MAX4332 op amp provided with this kit is very accurate but draws up to 500µA supply current. For improved supply current draw with a slight (0.4%) degradation in output voltage accuracy, replace the MAX4332 with a MAX4163, which draws 25µA (typ). The 2-pin header JU4 selects the overvoltage protection. The 2-pin header JU5 selects the shutdown mode. Table 4 lists the selectable jumper options. _______________________________________________________________________________________ 3 Evaluates: MAX1636 _______________Detailed Description The MAX1636 EV kit provides a digitally adjustable output voltage between 1.25V and 2V from a +7V to +22V input supply. The output voltage is digitally adjusted by the MAX5480, a multiplying DAC, which sums a variable output current into the FB feedback node. This DAC operates in voltage-output mode and relies on the precise MAX1636 REF output to generate an accurate reference current. The DAC has buffer amplifiers on the input and output to prevent the R2R ladder in the MAX5480 from excessively loading the reference or interacting with the normal FB resistor-divider impedance. The buffered DAC output swings 0V to REF 1LSB. Refer to Table 1 for the digital-to-analog (D/A) codes. The MAX1636 IC is rated for 30V input; however, the EV kit is restricted to 22V operating range (25V absolute maximum) due to the ratings of external components and minimum duty-factor limitations. D0 D1 D2 D3 REF U3B SYNC VCC SKIP VCC MAX4332 PGD VCC Figure 1. MAX1636 EV Kit Schematic _______________________________________________________________________________________ 1 8 8 4 100k R15 1M 2 7 1 2 2 3 6 JU4 4 5 1 1 C12 1µF JU3 R8 1M 0.1µF C5 2 JU2 1 R16 1M R6 100k R14 VCC 2 3 SW1A ON / OFF JU5 SW1B VCC SW1C 4 SW1D 1 X GND RESET D7 4 R12 1M D6 5 U1 D5 6 R10 1M D4 7 R9 1M D3 8 MAX5480 U2 VCC D2 9 3 1 VREF 2 1 N1 8 2 15 D1 6 5 MAX4332 U3A L1 2.2µH C1 10µF 25V +5V (OPTIONAL) N2 8 OUT2 D1 D0 10 11 3 GND 1500pF C11 4 5 2 6 7 3 C10 0.1µF 67 4 5 C13 4.7µF 16V D2 CMPSH-3 12 13 16 NC CS WR CC FB CSL CSH PGND DL LX BST DH VL 20Ω 14 R7 MAX1636 R11 1M 14 0.1µF VDD C9 OVP SYNC SKIP GND REF 12 V+ VCC 13 SHDN OUT1 VCC 5 8 20 10 7 9 3 4 C7 0.1µF C8 0.1µF 7 R1 0.01Ω C2 10µF 25V X = CUT HERE R5 51Ω R4 13.7k 0.1% C14 470µF 6.3V C3 10µF 25V R3 110k 0.1% R2 10k 0.1% C17 470µF OPEN X VIN 7V TO 22V C16 470µF 6.3V C18 OPEN C15 470µF 6.3V C4 10µF 25V SENSE VOUT Evaluates: MAX1636 MAX1636 CPU Supply Evaluation Kit MAX1636 CPU Supply Evaluation Kit Evaluates: MAX1636 1.0" 1.0" Figure 2. MAX1636 EV Kit Component Placement Guide— Component Side Figure 3. MAX1636 EV Kit Component Placement Guide— Solder Side _______________________________________________________________________________________ 5 Evaluates: MAX1636 MAX1636 CPU Supply Evaluation Kit 1.0" Figure 4. MAX1636 EV Kit PC Board Layout—Component Side 6 1.0" Figure 5. MAX1636 EV Kit PC Board Layout—Two Internal GND Planes _______________________________________________________________________________________ MAX1636 CPU Supply Evaluation Kit Evaluates: MAX1636 1.0" 1.0" Figure 6. MAX1636 EV Kit PC Board Layout—Three Internal GND Planes Figure 7. MAX1636 EV Kit PC Board Layout—Solder Side Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ______________________7 © 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.