19-2995; Rev 0; 9/03 MAX8529 Evaluation Kit Features ♦ Low Output Noise in DSL Band ♦ Ceramic Input/Output Capacitors ♦ Foldback Current Limit ♦ EV Kit Circuit Optimized for 8V to 13.2V Input ♦ >85% Efficiency ♦ Fixed-Frequency PWM Operation ♦ Adjustable 600kHz to 1.5MHz Switching Frequency ♦ External SYNC Input ♦ Clock Output for Master/Slave Synchronization ♦ Soft-Start and Soft-Stop ♦ RESET Output with 140ms Minimum Delay ♦ Lossless Current Limit (No Sense Resistor) ♦ Surface-Mount Components ♦ Fully Assembled and Tested Ordering Information Component List DESIGNATION QTY C1A, C1B, C12A, C12B C2, C11 PART DESCRIPTION 4 22µF, 6.3V X5R ceramic capacitors (1210) Taiyo Yuden JMK325BJ226MM 2 10µF, 25V X5R ceramic capacitors (1812) Taiyo Yuden TMK432BJ106KM C3, C10 2 0.1µF, 16V X7R ceramic capacitors (0603) TDK C1608X7R1C104K C4 1 330pF, 50V X7R ceramic capacitor (0603) TDK C1608X7R1H331K C5 1 1000pF, 50V X7R ceramic capacitor (0603) TDK C1608X7R1H102K C6, C14 2 27pF, 50V C0G ceramic capacitors (0603) TDK C1608C0G1H270J C7 1 0.22µF, 10V X5R ceramic capacitor (0603) Taiyo Yuden LMK107BJ224MA TEMP RANGE MAX8529EVKIT 0°C to +70°C IC PACKAGE 24 QSOP Recommended Equipment • • +8V to +13.2V, 5A, variable-output power supply Two dummy loads capable of sinking 3A • Two digital multimeters (DMM) Quick Start The MAX8529 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) Preset the power supply to +8V and turn off the power supply. 2) Connect the positive lead of the power supply to the VIN pad on the EV kit, and the negative lead of the power supply to the GND pad. 3) Connect the positive input of one DMM to VOUT1, and the negative input of the DMM to GND to measure the output voltage at VOUT1. 4) Connect the positive input of the other DMM to VOUT2, and the negative input of the DMM to GND to measure the output voltage at VOUT2. 5) Turn on the power supply and sweep the input voltage from 8V to 13.2V. ________________________________________________________________ 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: MAX8529 General Description The MAX8529 evaluation kit (EV kit) is a fully assembled and tested surface-mount circuit board demonstrating the MAX8529 dual, synchronized, step-down controller. The EV kit comes assembled with a circuit that steps down from an 8V to 13.2V input voltage, to output voltages of 1.8V and 3.3V. Both are capable of sourcing 3A. The switching frequency is set at 1.2MHz, and is adjustable from 600kHz to 1.5MHz with an external resistor. Alternatively, the controller can be synchronized to an external clock generated by another MAX8529 or a system clock. This device also features soft-start and soft-stop. The MAX8529 eliminates the need for current-sense resistors by utilizing the low-side MOSFET’s on-resistance as the current-sense element. The adjustable foldback current limit reduces power dissipation during short-circuit conditions. The MAX8529 includes a power-on reset output to signal the system when both outputs reach regulation. Evaluates: MAX8529 MAX8529 Evaluation Kit Component List (continued) DESIGNATION QTY C8 C9 C13 C15 C16, C17 DESCRIPTION 2 Dual N-channel MOSFETs, 30V, 35mΩ Fairchild FDS6912A 4.7µF, 10V X5R ceramic capacitor (1206) Taiyo Yuden LMK316BJ475ML R1, R2, R11, R12 4 6.8Ω ±5% resistors (0603) R3 1 21.5kΩ ±1% resistor (0603) 390pF, 50V C0G ceramic capacitor (0603) TDK C1608C0G1H391J R4 1 26.7kΩ ±1% resistor (0603) R5 1 620Ω ±5% resistor (0603) R6, R16 2 10kΩ ±5% resistors (0603) 22kΩ ±5% resistor (0603) 0.22µF, 35V X5R ceramic capacitor (0805) Taiyo Yuden GMK212BJ224KG 1 1 0 DESCRIPTION N1, N2 1 1 DESIGNATION QTY R7 1 R8, R18 2 68kΩ ±5% resistors (0603) R9, R20, R21 3 100kΩ ±5% resistors (0603) Not installed R10 1 10Ω ±5% resistor (0603) 1 24.9kΩ ±1% resistor (0603) 1500pF, 50V X7R ceramic capacitor (0603) TDK C1608X7R1H152K D1 1 100mA, 30V, dual Schottky diode Central Semiconductor CMPSH-3A R13 R14 1 10.7kΩ ±1% resistor (0603) 1 560Ω ±5% resistor (0603) 1 1.2µH, 5A inductor Coilcraft D01813P-122HC R15 L1 R17 1 130kΩ ±5% resistor (0603) 2.2µH, 7A inductor Coilcraft D03316P-222HC R19 1 4.99kΩ ±1% resistor (0603) L2 1 R22 0 Not installed U1 1 MAX8529EEG None 1 MAX8529 EV kit PC board Component Suppliers SUPPLIER Central Semiconductor COMPONENT PHONE WEBSITE Diodes 631-435-1110 www.centralsemi.com Coilcraft Inductors 800-322-2645 www.coilcraft.com Fairchild Semiconductor MOSFETs 800-341-0392 www.fairchildsemi.com Panasonic Resistors 714-373-7366 www.maco.panasonic.co.jp Taiyo Yuden Capacitors 408-573-4150 www.t-yuden.com TDK Capacitors 888-835-6646 www.component.tdk.com Note: Please indicate that you are using the MAX8529 when contacting these suppliers. 6) Verify that the VOUT1 output voltage is 1.8V over the entire input range. 7) Verify that the VOUT2 output voltage is 3.3V over the entire input range. 8) Connect one 3A load between VOUT1 and GND. 9) Verify that the VOUT1 output voltage is 1.8V. 10) Connect the second 3A load between VOUT2 and GND. 11) Verify that the VOUT2 output voltage is 3.3V. 2 Detailed Description Evaluating Other Output Voltages The output voltages for the MAX8529 are adjustable from sub-1V to +18V. Change R4 to modify the VOUT1 output voltage. Change R14 to modify the VOUT2 output voltage. Refer to the Setting the Output Voltage section in the MAX8529 data sheet for details. Components on the EV kit can require changes to optimize the circuit with the new output voltages. Refer to the Design Procedure section in the MAX8529 data sheet for details on calculating the values for these components. _______________________________________________________________________________________ MAX8529 Evaluation Kit RESET Output The RESET output is an open-drain output. RESET pulls low when either output falls below 90% of its nominal regulation voltage. Once both outputs exceed 90% of their nominal regulation voltages and both soft-start cycles are completed, RESET goes high impedance. To use a logic level other than VL, remove R9 and populate R22 with a 100kΩ resistor. This connects RESET to the user’s logic level at the VLB input. The MAX8529 EV kit provides a CKO output and SYNC input to evaluate the MAX8529 in 2-phase and 4-phase systems. Refer to the Clock Synchronization (SYNC, CKO) section in the MAX8529 data sheet for instructions on synchronizing two MAX8529 controllers. Pull EN low or connect to GND to shut down both regulators in the MAX8529. During shutdown, the supply current drops to 1mA and the output enters a highimpedance state. VL and REF remain active in shutdown. Pull EN high or connect to VL to enable both regulators in the MAX8529. Current Limit The MAX8529 EV kit demonstrates the foldback current-limit scheme utilized by the MAX8529. To modify the thresholds for the current limit and foldback current limit, change R7 and R8 for regulator one and R17 and R18 for regulator two. Refer to the Setting the Valley Current Limit section of the MAX8529 data sheet for the description of the current-limit schemes and instructions on calculating the resistor values. Shutdown Temperature Range The MAX8529 EV kit is designed to operate from 0°C to +70°C ambient. Above +50°C, airflow is required to keep the MOSFETs below their maximum junction temperature. The MAX8529 operates from -40°C to +85°C. _______________________________________________________________________________________ 3 Evaluates: MAX8529 Frequency and Synchronization The MAX8529 switching frequency is adjustable from 600kHz to 1.5MHz. Change R19 to adjust the switching frequency. Refer to the Setting the Switching Frequency section in the MAX8529 data sheet for more details. Components on the EV kit may require changes to optimize the circuit with the new switching frequency. Refer to the Design Procedure section in the MAX8529 data sheet for details on calculating the values for these components. 4 Figure 1. MAX8529 EV Kit Schematic _______________________________________________________________________________________ VLB RESET EN GND VOUT1 1.8V AT 3A C1A 22µF GND VIN 8V TO 13.2V R22 OPEN VL VL R9 100kΩ R7 22kΩ C5 1000pF R3 21.5kΩ R21 100kΩ C4 330pF C1B 22µF L1 1.2µH N1 FDS6912A C16 OPEN R5 620Ω R6 10kΩ R2 6.8Ω R1 6.8Ω C2 10µF C7 0.22µF R8 68kΩ C6 27pF R4 26.7kΩ C3 0.1µF 6 13 24 10 12 11 18 17 15 14 16 REF RST EN ILIM1 COMP1 FB1 PGND DL1 LX1 DH1 BST1 C8 0.22µF R10 10Ω 5 V+ 7 GND MAX8529 U1 19 VL C9 4.7µF OSC CKO SYNC ILIM2 COMP2 FB2 DL2 LX2 DH2 BST2 D1 CMPSH-3A 4 8 9 3 1 2 20 22 23 21 VL R19 4.99kΩ R18 68kΩ C14 27pF R14 10.7kΩ C10 0.1µF R12 6.8Ω R11 6.8Ω C11 10µF R16 10kΩ R15 560Ω R17 130kΩ C15 1500pF R13 24.9kΩ C12A 22µF R20 100kΩ C13 390pF L2 2.2µH N2 FDS6912A C17 OPEN C12B 22µF CKO SYNC GND VOUT2 3.3V AT 3A Evaluates: MAX8529 MAX8529 Evaluation Kit MAX8529 Evaluation Kit Evaluates: MAX8529 Figure 2. MAX8529 EV Kit Component Placement Guide—Top Silkscreen _______________________________________________________________________________________ 5 Evaluates: MAX8529 MAX8529 Evaluation Kit Figure 3. MAX8529 EV Kit PC Board Layout—Component Side 6 _______________________________________________________________________________________ MAX8529 Evaluation Kit Evaluates: MAX8529 Figure 4. MAX8529 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 © 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.