19-2165; Rev 0; 10/01 MAX1813 Evaluation Kit Features ♦ High Speed, Accuracy, and Efficiency ♦ IMVP-II/Coppermine/AMD Compatible ♦ Voltage-Positioned Output ♦ Low Output-Capacitor Count (6) ♦ Fast-Response Quick-PWM™ Architecture ♦ 7V to 24V Input Voltage Range ♦ 0.925V to 2.0V Output Voltage Range (Coppermine/AMD, 5-Bit DAC) ♦ 0.6V to 1.75V Output Voltage Range (IMVP-II, 5-Bit DAC) ♦ 22A Load-Current Capability ♦ 300kHz Switching Frequency ♦ Power Good (PGOOD) Indicator ♦ 28-Pin QSOP Package ♦ Low-Profile Components ♦ Fully Assembled and Tested Ordering Information PART MAX1813EVKIT TEMP. RANGE IC PACKAGE 0°C to +70°C 28 QSOP Component List DESIGNATION C1–C4, C20 QTY 5 C5, C6, C7, C10, C13, C16 6 C8 1 C9 1 C11, C12 2 DESCRIPTION 10µF, 25V ceramic capacitors (1812) Taiyo Yuden TMK432BJ106KM TDK C4532X5R1E106M 220µF, 2.5V, 15mΩ low-ESR specialty polymer capacitors Panasonic EEFUE0E221R 10µF, 6.3V X5R ceramic capacitor (1210) Taiyo Yuden JMK325BJ106MN TDK C3216X5R0J106M 0.1µF ceramic capacitor (0805) 0.22µF, 16V X5R ceramic capacitors (0805) Taiyo Yuden EMK212BJ224KG DESIGNATION QTY DESCRIPTION C14 1 47pF ceramic capacitor (0805) C15 1 1µF, 10V X5R ceramic capacitor (0805) Taiyo Yuden LMK212BJ105KG TDK C2012X5R105M C18, C27 2 1000pF ceramic capacitors (0805) C17, C19, C23, C24, C25 5 4700pF ceramic capacitors (0805) C21, C22, C26 0 Not installed D1 1 5A Schottky diode Central Semiconductor CMSH5-40 D2 1 100mA Schottky diode Central Semiconductor CMPSH-3 Quick-PWM is a trademark of Maxim Integrated Products, Inc. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 Evaluates: MAX1813 General Description The MAX1813 evaluation kit (EV kit) demonstrates the high-power, dynamically adjustable notebook CPU application circuit. This DC-DC converter steps down high-voltage batteries and/or AC adapters, generating a precision, low-voltage CPU core VCC rail. The MAX1813 EV kit meets the Intel mobile CPU’s transient voltage specification (IMVP-II/Coppermine), using voltage positioning to minimize the output-capacitor requirements. The MAX1813 has an internal multiplexer which accepts three unique 5-bit VID DAC codes corresponding to performance, battery, and suspend modes. Precision slew-rate control provides “just-intime” arrival at the new DAC setting, minimizing surge currents to and from the battery. This fully assembled and tested circuit board provides a digitally adjustable 0.6V to 2.0V output from a 7V to 24V battery input range. It delivers up to 22A output current. The EV kit operates at 300kHz switching frequency and has superior line- and load-transient response. MAX1813 Evaluation Kit Evaluates: MAX1813 Component List (continued) DESIGNATION QTY D3 1 DESIGNATION QTY None 12 200mA Switching diode Central Semiconductor CMPD2838 DESCRIPTION Shunts J1 1 Scope probe connector Berg Electronics 33JR135-1 None 1 Rubber bumpers 3M SJ-5007, Mouser 517-SJ5007BK or equivalent MAX1813 PC board JU1, JU2 2 4-pin headers None 1 MAX1813 data sheet None 1 MAX1813 EV kit data sheet None 4 JU8 1 3-pin header JUA0–JUA4, JUB0–JUB4 10 2-pin headers JU3, JU4, JU5, JU6 0 Not installed Central Semiconductor 516-435-1110 516-435-1824 Fairchild 408-721-2181 408-721-1635 1 0.68µH power inductor Toko EH125C-R60N or Sumida CEP125 #4712-T011 or Sumida CDEP134H-0R6 or Panasonic ETQP6F0R6BFA International Rectifier 310-322-3331 310-322-3332 Panasonic 714-373-7939 714-373-7183 Sumida 708-956-0666 708-956-0702 N-channel MOSFETs (SO-8) International Rectifier IRF7811W International Rectifier IRF7811 Taiyo Yuden 408-573-4150 408-573-4159 L1 N1, N2 2 DESCRIPTION 2 N3, N4, N5 3 R1 1 N-channel MOSFETs (SO-8) International Rectifier IRF7822 Fairchild FDS7764A 20Ω ±5% resistor (0805) R2–R6, R9, R22–R27 13 100kΩ ±5% resistors (0805) R7 0 Not installed (short PC trace) (0805) R8, R11 2 R12 1 R13, R28 2 100Ω ±5% resistors (0805) 0.0015Ω ±5% 1W resistor (2512) Panasonic ERJM1WTJ1M5U 10kΩ ±5% resistors (0805) R14 1 51.1kΩ ±1% resistor (0805) R15 1 20kΩ ±5% resistor (0805) R16 1 300kΩ ±5% resistor (0805) R17 1 200kΩ ±5% resistor (0805) R18, R19 0 Not installed (0805) R20 1 150kΩ ±5% resistor (0805) R29 1 Not installed (2512) SW1 1 DIP-8 dip switch U1 1 MAX1813EEI (28-QSOP) Component Suppliers SUPPLIER PHONE FAX TDK 847-390-4373 847-390-4428 Toko 408-432-8281 408-943-9790 Recommended Equipment • 7V to 24V, >30W power supply, battery, or notebook AC adapter • DC bias power supply, 5V at 100mA • Dummy load capable of sinking 22A • Digital multimeter (DMM) • 100MHz dual-trace oscilloscope Quick Start 1) Ensure that the circuit is connected correctly to the supplies and dummy load prior to applying any power. 2) Set switches SW1-A (SHDN) and SW1-C (ZMODE) to the ON position, and SW1-B (SKIP) to the OFF position. This configures the EV kit for fixed-frequency PWM-mode operation. The DAC code settings (D4–D0) are set for 1.30V output for the impedancemode configuration through jumpers JUB4, JUB2, and JUB1, and to 1.15V output for the logic mode configuration through installed jumpers JUA4, JUA1, and JUA0 (CODE = 1, JU8 pins 1 and 2). 3) Turn on the battery power before turning on the 5V bias power; otherwise, the output UVLO timer will time out, and the FAULT latch will be set, disabling the regulator until 5V power is cycled or shutdown is toggled. _______________________________________________________________________________________ MAX1813 Evaluation Kit Detailed Description This 22A buck-regulator design is optimized for a 300kHz frequency and output voltage settings around 1.15V to 1.3V. At VOUT = 1.3V, inductor ripple is approximately 30%. Setting the Output Voltage The MAX1813 has a unique internal multiplexer that can select one of three different VID DAC code settings for different processor states. Depending on the logic level at SUS (SW1-D), the suspend mode multiplexer selects the VID DAC code settings from either the ZMODE multiplexer, or the S0/S1 (JU1, JU2) input decoder. The output voltage can be digitally set from 0.925V to 2.0V (Table 1, CODE = 0, JU8 pins 2 and 3) or from 0.6V to 1.75V (Table 1, CODE = 1, JU8 pins 1 and 2) from the D0–D4 pins, and from 0.6V to 0.975V (Table 2) from S0/S1 pins. There are four different ways of setting the output voltage: 1) Drive the external VID0–VID4 inputs (no jumpers installed). Set the output voltage by driving the VID0–VID4 with open-drain drivers (pullup resistors are included on the board) or 3V/5V CMOS output logic levels. The internal multiplexer must be in the logic-mode configuration (ZMODE = low, SUS = low) 2) Install jumpers JUA0–JUA4 (logic-mode configuration: SW1-C OFF, ZMODE = low, and SW-D OFF, SUS = low). When JUA0–JUA4 are not installed, the MAX1813’s D0–D4 inputs are at logic 1 (connected to VCC). When JUA0–JUA4 are installed, D0–D4 inputs are at logic 0 (connected to GND). In the logic-mode configuration, change the output voltage during operation by installing and removing jumpers JUA0–JUA4. As shipped, the EV kit is configured for operation in the logic mode with jumpers JUA0–JUA4 set for 1.15V output (Table 1). 3) Install jumpers JUB0–JUB4 (impedance-mode configuration: SW1-C ON, ZMODE = high, and SW1-D OFF, SUS = low). When JUB0–JUB4 are not installed, a 100kΩ resistor is in series with each of the D0–D4 inputs, making it a logic 1. When JUB0–JUB4 are installed, the 100kΩ resistors are shorted, making D0–D4 logic 0. As shipped, the EV kit is configured for operation in the impedance mode with jumpers JUB0–JUB4 set for 1.30V output (Table 1). While in the impedance mode, changing jumpers JUB0–JUB4 does not immediately change the output voltage setting. SHDN, ZMODE, SUS, or VBIAS must be cycled to sample the new jumper settings. Refer to the MAX1813 data sheet for more information. 4) Install jumpers JU1 and JU2 (suspend-mode configuration: SW1-D ON, SUS = high). As shipped, the EV kit is configured for operation in the suspend mode with jumpers JU1 and JU2 set for 0.85V output (Table 2). In the suspend mode, change the output voltage during operation by installing and removing jumpers JU1 and JU2. Refer to the MAX1813 data sheet for more information. Dynamic Output Voltage Transition Experiment Observe the output voltage transition between: 1) 0.85V and 1.15V by setting SW1-C OFF (ZMODE = low) and toggling SW1-D (SUS) position between ON and OFF. 2) 1.15V and 1.30V by toggling the SW1-C (ZMODE) position between ON and OFF (SW1-D OFF, SUS = low). 3) 0.85V and 1.30V by setting SW1-C ON (ZMODE = high) and toggling SW1-D (SUS) position between ON and OFF. This is the worst-case transition and should complete within 100µs. This EV kit is set to transition the output voltage at 8.8mV/µs. Alter the speed of the transition by changing resistor R14 (51.1kΩ). Longer-than-expected transitions maybe observed due to switch bounce (SW1). To eliminate switch bounce, set SW1-D (SUS) to the OFF position, and drive the SUS pin (TP2) with a function generator. During the voltage transition, watch the inductor current by looking across R12 with a differential scope probe or by inserting a current probe in series with the inductor. Observe the low, well-controlled inductor current that accompanies the voltage transition. The same slew rate and controlled inductor current are used during shutdown and start up, resulting in well-controlled currents into and out of the battery (input source). _______________________________________________________________________________________ 3 Evaluates: MAX1813 4) Observe the 1.30V output voltage with the DMM and/or oscilloscope. Look at the LX switching-node and MOSFET gate-drive signals while varying the load current. 5) Toggle the ZMODE switch, and observe the output voltage transition to the new 1.15V setting. Note: When driving ZMODE with the dip switch, the transition may take longer than expected due to switch bounce. Evaluates: MAX1813 MAX1813 Evaluation Kit Table 1. MAX1813 Output Voltage Adjustment Settings D4 JUA4 JUB4 D3 JUA3 JUB3 D2 JUA2 JUB2 D1 JUA1 JUB1 D0 JUA0 JUB0 OUTPUT VOLTAGE CODE = 0 (JU8 PINS 2 AND 3) OUTPUT VOLTAGE CODE = 1 (JU8 PINS 1 AND 2) 0 0 0 0 0 2.000V 1.750V 0 0 0 0 1 1.950V 1.700V 0 0 0 1 0 1.900V 1.650V 0 0 0 1 1 1.850V 1.600V 0 0 1 0 0 1.800V 1.550V 0 0 1 0 1 1.750V 1.500V 0 0 1 1 0 1.700V 1.450V 0 0 1 1 1 1.650V 1.400V 0 1 0 0 0 1.600V 1.350V 0 1 0 0 1 1.550V 1.300V 0 1 0 1 0 1.500V 1.250V 0 1 0 1 1 1.450V 1.200V 0 1 1 0 0 1.400V 1.150V 0 1 1 0 1 1.350V 1.100V 0 1 1 1 0 1.300V 1.050V 0 1 1 1 1 NO CPU* 1.000V 1 0 0 0 0 1.275V 0.975V 1 0 0 0 1 1.250V 0.950V 1 0 0 1 0 1.225V 0.925V 1 0 0 1 1 1.200V 0.900V 1 0 1 0 0 1.175V 0.875V 1 0 1 0 1 1.150V 0.850V 1 0 1 1 0 1.125V 0.825V 1 0 1 1 1 1.100V 0.800V 1 1 0 0 0 1.075V 0.775V 1 1 0 0 1 1.050V 0.750V 1 1 0 1 0 1.025V 0.725V 1 1 0 1 1 1.000V 0.700V 1 1 1 0 0 0.975V 0.675V 1 1 1 0 1 0.950V 0.650V 1 1 1 1 0 0.925V 0.625V 1 1 1 1 1 NO CPU* 0.600V *In the no-CPU state, DH and DL are held low and the slew-rate controller is set for 0.425V. 4 _______________________________________________________________________________________ MAX1813 Evaluation Kit Table 2. Output Voltage Adjustment Settings, Suspend Mode SHUNT LOCATION JU2 SHUNT LOCATION JU1 S1 PIN S0 PIN 1, 2 1, 2 GND GND 0.975V 1, 2 1, 3 GND REF 0.950V 1, 2 Not installed GND OPEN 0.925V 1, 2 1, 4 GND VCC 0.900V 1, 3 1, 2 REF GND 0.875V Load-Transient Experiment One interesting experiment is to subject the output to large, fast-load transients and observe the output with an oscilloscope. This necessitates careful instrumentation of the output, using the supplied scope-probe jack. Accurate measurement of output ripple and load-transient response invariably requires that ground clip leads be completely avoided and that the probe be removed to expose the GND shield, so the probe can be plugged directly into the jack. Otherwise, EMI and noise pickup will corrupt the waveforms. Most benchtop electronic loads intended for powersupply testing lack the ability to subject the DC-DC converter to ultra-fast load transients. Emulating the supply current di/dt at the CPU VCORE pins requires at least 10A/µs load transients. One easy method for generating such an abusive load transient is to solder a power MOSFET directly across the scope-probe jack. Then drive its gate with a strong pulse generator at a low duty cycle (10% or less) to minimize heat stress in the MOSFET. Vary the high-level output voltage of the pulse generator to vary the load current. To determine the load current, one might expect to insert a meter in the load path, but this method is prohibited here by the need for low resistance and inductance in the path of the dummy load MOSFET. There are two easy alternative methods of determining how much load current a particular pulse-generator amplitude is causing. The first and best is to observe the inductor current with a calibrated AC current probe, OUTPUT VOLTAGE 1, 3 1, 3 REF REF 0.850V 1, 3 Not installed REF OPEN 0.825V 1, 3 1, 4 REF VCC 0.800V Not installed 1, 2 OPEN GND 0.775V Not installed 1, 3 OPEN REF 0.750V Not installed Not installed OPEN OPEN 0.725V Not installed 1, 4 OPEN VCC 0.700V 1, 4 1, 2 VCC GND 0.675V 1, 4 1, 3 VCC REF 0.650V 1, 4 Not installed VCC OPEN 0.625V 1, 4 1, 4 VCC VCC 0.600V such as a Tektronix AM503 or by looking across R12 with a differential probe. In the buck topology, the load current is equal to the average value of the inductor current. The second method is to put on a static dummy load and measure the battery current. Then connect the MOSFET dummy load at 100% duty momentarily and adjust the gate-drive signal until the battery current rises to the appropriate level (the MOSFET load must be well heat-sinked for this to work without causing smoke and flames). Table 3. Switch SW1-A/SW1-B Functions (SHDN, SKIP) SW1-A SW1-B OFF X CONNECTION EFFECT SKIP, SHDN connected to GND through R15 and R17 Shutdown mode, VOUT = 0V ON ON SKIP, SHDN connected to VCC through R15 Output enabled. SKIP mode operation. Allows automatic PWM/PFM switchover for pulse skipping at light-load for highest efficiency. Refer to the Forced PWM Mode section in the MAX1813 data sheet for more information. ON OFF SKIP, SHDN connected to +2V through R15 and divider R16/R17 Output enabled. Low-noise mode. Forced fixed-frequency PWM operation. Recommended for output voltage transitions. _______________________________________________________________________________________ 5 Evaluates: MAX1813 There are two other methods to create an output voltage transition. Select D0–D4 logic mode by setting the ZMODE switch to the OFF position (SW1-C). Then either manually change the JUA0–JUA4 jumpers to a new VID code setting (Table 1), or remove all jumpers and drive the VID0–VID4 PC board test points externally to the desired code settings. Evaluates: MAX1813 MAX1813 Evaluation Kit Table 4. Switch SW1-C/SW1-D Functions (ZMODE, SUS for IMVP II, Code = 1) SW1-C SW1-D ON OFF ZMODE connected to VCC, SUS connected to GND CONNECTION Impedance Mode INTERNAL MULTIPLEXER OFF OFF ZMODE connected to GND, SUS connected to GND Logic Mode X ON SUS connected to VCC Suspend Mode Table 5. Jumpers JU3/JU4/JU5 Functions (Switching-Frequency Selection) SHUNT LOCATION TON PIN FREQUENCY (kHz) JU3 Installed JU4 Not Installed JU5 Not Installed Connected to VCC 200 Not Installed Installed Not Installed Connected to REF 550 Not Installed Not Installed Installed Connected to GND 1000 Not Installed Not Installed Not Installed Floating 300 (as shipped) IMPORTANT: Don’t change the operating frequency without first recalculating component values. The frequency has a significant effect on the inductor peak current, MOSFET heating, preferred inductor value, PFM/PWM switchover point, output noise, efficiency, and other critical parameters. Table 6. Jumper JU6 Functions (Fixed/Adjustable Current-Limit Selection) SHUNT POSITION 6 ILIM PIN CURRENT-LIMIT THRESHOLD ON Connected to VCC 50mV (default) OFF Connected to an external resistor divider, R18/R19. Refer to the Pin Description ILIM section in the MAX1813 data sheet for more information. Adjustable between 50mV to 200mV. _______________________________________________________________________________________ MAX1813 Evaluation Kit Evaluates: MAX1813 Table 7. Troubleshooting Guide SYMPTOM POSSIBLE PROBLEM Circuit won’t start when power is applied. SOLUTION Power-supply sequencing: 5V bias supply was applied before battery voltage. Cycle SW1-A SHDN. Output overvoltage due to shorted high-side MOSFET Replace the MOSFET. Output overvoltage due to load recovery overshoot Reduce the inductor value, raise the switching frequency, or add more output capacitance. Output overload condition Remove excessive load. Broken connection, bad MOSFET, or other catastrophic problem Troubleshoot the power stage. Are the DH and DL gate-drive signals present? Is the 2V VREF present? VBATT power source has poor impedance characteristic. Add a bulk electrolytic bypass capacitor across the benchtop power supply, or substitute a real battery. Excessive EMI, poor efficiency at high input voltages. Gate-drain capacitance of N3/N4/N5 is causing shoot-through cross-conduction. Observe the gate-source voltage of N3/N4/N5 during the low-to-high LX node transition (this requires careful instrumentation). Is the gate voltage being pulled above 1.5V, causing N3/N4/N5 to turn on? Use a smaller low-side MOSFET or add a BST resistor (R7). Poor efficiency at high input voltages, N1/N2 get hot. N1/N2 has excessive gate capacitance. Use a smaller/faster high-side MOSFET or add more heatsinking. Circuit won’t start when +5V bias supply cycled. On-time pulses are erratic or have unexpected changes in period. _______________________________________________________________________________________ 7 8 VCC 1 8 REF 3 JU3 200kHz SW1-B SKIP 2 SW1-C ZMODE VCC 7 6 REF REF 2V R17 200kΩ R16 300kΩ SW1-A SHDN VBATT 7V TO 24V 3 C14 47pF TP1 REF 2 4 JU1 1 VCC JU5 1MHz R18 OPEN VCC R19 OPEN 2 8 7 12 10 C12 0.22µF JU6 VCC 6 4 3 19 25 24 23 22 21 R20 150kΩ 11 R14 51.1kΩ 1% TP3 4 JU2 3 1 JU4 550kHz FLOAT = 300kHz R15 20kΩ R27 100kΩ R13 10kΩ D0 D1 D2 D3 D4 S1 S0 ILIM TON REF CC TIME U1 R1 20Ω MAX1813 SKP/SDN ZMODE D0 D1 D2 D3 D4 VCC C11 0.22µF V+ PGND SUS GND PGOOD CODE FB VPCS DL LX DH BST VDD 15 18 14 13 1 2 3 VCC VBATT C2 10µF 25V R8 100Ω 4 R28 10kΩ VCC VCC R4 100kΩ R12 1.5mΩ 1 2 3 5 6 7 8 C9 0.1µF 4 4 C20 10µF 25V C15 1µF N4 VDD C4 10µF 25V D2 CMPSH-3 R11 100Ω 4 C18 1000pF N3 C3 10µF 25V SW1-D R27 SUS 100kΩ 1 2 3 5 6 7 8 R7 SHORT (PC TRACE) C27 1000pF TP2 20 JU8 5 2 16 27 28 26 1 C1 10µF 25V PGOOD 1 2 3 5 6 7 8 1 2 3 5 6 7 8 N5 N1 D1 L1 0.68µH 3 2 1 N2 8 7 6 5 C22 OPEN R29 OPEN +5V VBIAS C21 OPEN 4 C5 220µF 2.5V C6 220µF 2.5V D3 C10 220µF 2.5V C7 220µF 2.5V VDD C13 220µF 2.5V C16 220µF 2.5V C26 OPEN C8 10µF 6.3V J1 SCOPE JACK GND VOUT Evaluates: MAX1813 MAX1813 Evaluation Kit Figure 1. MAX1813 EV Kit Schematic _______________________________________________________________________________________ _______________________________________________________________________________________ VID0 VID1 VID2 VID3 VID4 VCC VCC VCC VCC R22 100kΩ R23 100kΩ R24 100kΩ R25 100kΩ R26 100kΩ C17 4700pF C19 4700pF C23 4700pF C24 4700pF C25 4700pF JUA0 JUA1 JUA2 JUA3 JUA4 R9 100kΩ JUB0 R6 100kΩ JUB1 R5 100kΩ JUB2 R3 100kΩ JUB3 R2 100kΩ JUB4 D0 D1 D2 D3 D4 Evaluates: MAX1813 VCC MAX1813 Evaluation Kit Figure 1. MAX1813 EV Kit Schematic (continued) 9 Evaluates: MAX1813 MAX1813 Evaluation Kit 1.0" Figure 2. MAX1813 EV Kit Component Placement Guide—Top Silkscreen 1.0" Figure 4. MAX1813 EV Kit PC Board Layout—Ground Layer 2 10 1.0" Figure 3. MAX1813 EV Kit PC Board Layout—Component Side 1.0" Figure 5. MAX1813 EV Kit PC Board Layout—Ground Layer 3 ______________________________________________________________________________________ MAX1813 Evaluation Kit Evaluates: MAX1813 1.0" 1.0" Figure 6. MAX1813 EV Kit PC Board Layout—Solder Side Figure 7. MAX1813 EV Kit Component Placement Guide — Bottom Silkscreen 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 ____________________ 11 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.