19-0804; Rev 2; 6/08 MAX15020 Evaluation Kit Features The MAX15020 evaluation kit (EV kit) is a fully assembled and tested PCB that evaluates the MAX15020 PWM step-down regulator IC with an integrated high-side switch. The MAX15020 is equipped with a reference input for the feedback error amplifier, allowing dynamic output-voltage programming. The MAX15020 EV kit operates over a wide input-voltage range of 7.5V to 40V and provides up to 2A. The MAX15020 internal switching frequency can be set to either 300kHz or 500kHz. The MAX15020 EV kit features a SYNC input to provide external frequency synchronization for sensitive applications. The EV kit uses a MAX15020 step-down regulator in a 20-pin thin QFN package. The MAX15020 IC operates over the automotive temperature range of -40C to +125C and is suitable for printers, industrial, and automotive applications. o Wide 7.5V to 40V Input Range o Dynamic Output-Voltage Control from 0.8V to 36V with 2A Load o Selectable 300kHz/500kHz Switching Frequency o Turn-On/Off Control o Demonstrates MAX15020 IC Low Shutdown Current o High Efficiency up to 96% (VIN = 36V, VOUT = 30V, ILOAD = 2A) o Demonstrates MAX15020 IC Over-Current and Thermal Protection o Space-Saving 5mm x 5mm, 20-pin TQFN Package o Fully Assembled and Tested Ordering Information PART TYPE MAX15020EVKIT+ EV Kit +Denotes lead-free and RoHS compliant. Component List DESIGNATION C1, C6 QTY 2 DESCRIPTION 560F 20%, 50V low ESR electrolytic capacitors (12.5mm x 25mm) SANYO 50ME560WX C2, C4, C10 3 1F 10%, 25V X7R ceramic capacitors (0805) TDK C2012X7R1E105K C3, C5, C7, C9 4 0.1F 10%, 50V X7R ceramic capacitors (0603) TDK C1608X7R1H104K C8 C11 C12 C13 1 0.22F 10%, 50V X7R ceramic capacitor (0805) Murata GRM21BR71H224K 1 0.027F 10%, 50V X7R ceramic capacitor (0603) AVX 06035C273KAT2A 1 0.1F 10%, 50V X7R ceramic capacitor (0805) TDK C2012X7R1H104K 330pF 5%, 50V C0G ceramic capacitor (0603) TDK C1608C0G1H331J 1 DESIGNATION QTY DESCRIPTION D1 1 60V, 3A Schottky diode (SMA) Diodes Inc. B360A D2 1 100V, 150mA Schottky diode (SOD-123) Vishay BAT46W JU1, JU2, JU3 3 3-pin headers L1 1 22H, 4.7A inductor Sumida CDRH127/LDNP-220MC R1 1 97.6k 1% resistor (0603) R2 1 4.02k 1% resistor (0603) R3, R4 2 10k 5% resistors (0603) 10 5% resistor (0603) R5 1 R6, R7 2 10k 1% resistors (0603) R8 1 340 1% resistor (0603) R9 1 15.8k 1% resistor (0603) R10 1 0 5% resistor (0603) R11 1 20k 1% resistor (0603) TP1-TP4 4 PC mini red test points U1 1 MAX15020ATP+ 20-pin TQFN (5mm x 5mm x 0.8mm) -- 3 Shunts (JU1, JU2, JU3) -- 1 PCB: MAX15020 Evaluation Kit+ ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. 1 Evaluates: MAX15020 General Description Evaluates: MAX15020 MAX15020 Evaluation Kit Component Suppliers SUPPLIER PHONE WEBSITE AVX Corp. 843-448-9411 www.avxcorp.com Diodes Inc. 805-446-4800 www.diodes.com Murata 770-436-1300 www.murata.com SANYO 619-661-6835 www.sanyodevice.com Sumida Corp. 847-545-6700 www.sumida.com TDK Corp. 847-803-6100 www.component.tdk.com Vishay 203-268-6261 www.vishay.com Note: Indicate that you are using the MAX15020 when contacting these component suppliers. Quick Start Recommended Equipment Before beginning, the following equipment is needed: * 7.5V to 40V adjustable, 3A power supply * 15 resistive load rated for 75W or greater * Two digital voltmeters Procedure The MAX15020 EV kit is fully assembled and tested. Follow these steps to verify board operation. Caution: Do not turn on the power supply until all connections are completed. tion. The MAX15020 step-down regulator features an internal high-side-low RDS(ON) MOSFET to achieve higher efficiency and lower overall system cost. The MAX15020 also features configurable soft-start, shutdown control, cycle-by-cycle current limit, hiccup-mode output short-circuit protection, and thermal shutdown. The undervoltage lockout (UVLO) threshold is configurable by choosing the appropriate R1 and R2 resistors. The MAX15020 EV kit features a selectable 300kHz or 500kHz switching-frequency operation, in addition to a SYNC input that can be used to synchronize the MAX15020 to frequencies operating in the 300kHz to 500kHz range. An external reference input (REFIN_EXT) is available to dynamically change the output voltage. Jumper Selection ON/OFF Mode The MAX15020 EV kit features a ON/OFF mode that reduces the MAX15020 supply current to 6A (typ). The 3-pin jumper JU1 selects the ON/OFF mode for the MAX15020 EV kit. See Table 1 for jumper JU1 configurations. OFF Mode Table 1. Jumper JU1 ON/O SHUNT LOCATION ON/OFF PIN MAX15020 OUTPUT 1-2 Connects to VIN directly MAX15020 enabled 1) Verify that a shunt is not installed at jumper JU1 (default 32V turn-on voltage). 2-3 Connects to GND MAX15020 disabled 2) Verify that shunts are installed on pins 1-2 of jumpers JU2 (REFIN = REFOUT) and JU3 (300kHz switching frequency). None* Connects to VIN through R1 and R2 resistors MAX15020 enabled at VIN 32V 3) Connect the resistive load between the OUT PCB pad and the PGND PCB pad. 4) Connect digital voltmeters across the IN and PGND pads, and the OUT and PGND pads on the EV kit board. 5) Connect the power supply's positive terminal to the IN PCB pad on the EV kit, and connect the powersupply ground terminal to the PGND PCB pad. 6) Turn on the power supply. 7) Set the power-supply voltage to 36V. 8) Verify that the voltmeter at OUT measures 30V. Detailed Description of Hardware The MAX15020 EV kit circuit uses a MAX15020 stepdown regulator IC (U1) to implement a step-down DCDC regulator circuit. The EV kit operates over a 7.5V to 40V input range. The circuit provides a dynamically programmable output range of 0.8V to 36V and can deliver up to 2A of current with excellent line and load regula2 *Default position. REFIN_EXT Input The MAX15020 features a reference input for the internal error amplifier. The voltage applied to REFIN_EXT PCB pad is used to dynamically change the circuit's output voltage. Jumper JU2 connects REFIN to REFOUT to use the MAX15020's 1V internal reference voltage. See Table 2 for jumper JU2 configurations. To change the MAX15020 EV kit output voltage using REFIN_EXT, refer to the Setting the Output Voltage section in the MAX15020 IC data sheet. Table 2. Jumper JU2 Reference-Voltage Input SHUNT LOCATION REFIN PIN VOUT 1-2* Connects directly to REFOUT 30V 2-3 Externally controlled by REFIN_EXT voltage Dependent on voltage at REFIN_EXT *Default position. _______________________________________________________________________________________ MAX15020 Evaluation Kit Table 3. Jumper JU3 Frequency Selection SHUNT LOCATION FSEL PIN MAX15020 SWITCHING FREQUENCY 1-2* Connects to VREG 300kHz 2-3 Connects to GND 500kHz *Default position. When operating the MAX15020 with an external clock signal at SYNC, place the shunt on pins 1-2. Refer to the Oscillator/Sychronization Input section of the MAX15020 IC data sheet for more information. Configuring the Output Voltage (OUT) The MAX15020 EV kit step-down regulator output voltage is configured to 30V by resistors R7 and R8, and with REFIN = REFOUT. The EV kit's output voltage (OUT) can be reconfigured in the range of 0.8V to 36V by replacing resistors R7 and R8. To select a new value for resistor R8, refer to the Compensation Design section in the MAX15020 IC data sheet. Use the following equation to reconfigure the output voltage to the desired value: R7 R8 = VOUT - 1 V REFIN where V OUT is the desired output voltage in volts, V REFIN is the voltage supplied by REFOUT or REFIN_EXT, and R7 is typically 10k. The MAX15020 output voltage can also be adjusted dynamically by driving REFIN_EXT between 0 and 3.6V. To use the REFIN_EXT input, place a shunt across pins 2-3 of jumper JU2. Reconfiguring the MAX15020 EV kit for a new output voltage may require replacing inductor L1 and capacitors C1 and/or C6 . To select a new value for inductor L1 and capacitors C1 and C6, refer to the Inductor Selection , Output Capacitor Selection, and Input Capacitor Selection sections, respectively, in the MAX15020 IC data sheet. Configuring the ON/OFF Threshold The MAX15020 EV kit turn-on threshold is configured to 32V with resistors R1 and R2. The MAX15020 turns on when the input voltage (VIN) is approximately above 32V and ON/OFF is 1.23V. The ON/OFF threshold can be reconfigured to a desired value by appropriately selecting resistors R1 and R2. Refer to Setting the ON/OFF Threshold section in the MAX15020 IC data sheet. To reconfigure the UVLO threshold, use the following equation: V R1 = R2 x UVLO - 1 1.23 where resistor R1 should be in the range of 100k and VUVLO is the desired UVLO threshold in volts. Place a shunt across pins 1-2 of jumper JU1 for alwayson operation, which bypasses the on/off threshold. Resistor R11 is utilized to prevent excessive power dissipation in resistor R2 when the shunt at jumper JU1 is installed on pins 1-2. Synchronization Input (SYNC) The MAX15020 EV kit circuit features a selectable 300kHz or 500kHz switching frequency. Jumper JU3 sets the internal switching frequency. The EV kit's SYNC PCB pad can be used to synchronize the MAX15020 with an external digital clock in the range of 300kHz to 500kHz. When SYNC is driven with an external digital clock, the MAX15020 synchronizes to the rising edge of the external clock. The digital square-wave clock source must provide the following signal qualities: * Output voltage: Logic-low = 0 to 0.8V, logic-high = 2V to 5.5V * Input frequency = 300kHz to 500kHz (refer to the MAX15020 IC data sheet for more information on the SYNC input) * Minimum pulse width = 200ns To use external synchronization, connect the external square-wave clock to the SYNC and GND pads. _______________________________________________________________________________________ 3 Evaluates: MAX15020 Frequency Selection Jumper JU3 selects the MAX15020 operating switching frequency between 300kHz or 500kHz. See Table 3 for switching frequency selection. 4 GND ON/OFF PGND IN R2 4.02k 1% R1 97.6k 1% 3 1 2 R3 10k REFOUT C8 0.22F TP1 3 1 2 FB COMP C5 0.1F 50V REFOUT JU1 R11 20k 1% REFIN_EXT C1 560F 50V JU2 U1 6 3 8 1 SYNC TP2 JU3 2 7 18 17 16 C3 0.1F 50V R4 10k R5 10 9 13 14 15 12 BST 11 N.C. LX LX LX VREG 10 NDVREG PGND VIN VIN VIN MAX15020 C2 1F CSS REFIN FSEL SYNC REFOUT ON/OFF FB COMP C9 0.1F 50V 5 4 3 2 1 19 GND VREG 20 VREG C10 1F R10 0 TP3 C4 1F TP4 D2 R6 10k 1% R8 340 1% C11 0.027F D1 L1 22H C12 0.1F R9 15.8k 1% R7 10k 1% C7 0.1F 50V C13 330pF FB COMP C6 560F 50V PGND OUT Evaluates: MAX15020 MAX15020 Evaluation Kit Figure 1. MAX15020 EV Kit Schematic _______________________________________________________________________________________ MAX15020 Evaluation Kit Evaluates: MAX15020 Figure 2. MAX15020 EV Kit Component Placement Guide-- Component Side Figure 3. MAX15020 EV Kit PCB Layout--Component Side _______________________________________________________________________________________ 5 Evaluates: MAX15020 MAX15020 Evaluation Kit Figure 4. MAX15020 EV Kit PCB Layout--GND Layer 2 6 _______________________________________________________________________________________ MAX15020 Evaluation Kit REVISION NUMBER REVISION DATE 0 4/07 Initial release 1 11/07 Updated Ordering Information table format; corrections to Procedures (step 2), Configuring ON/OFF Threshold, and Figure 1. 2 6/08 Changed part number for C13 in Component List. REVISION DESCRIPTION PAGES CHANGED -- 1-4 1 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 (c) 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. Evaluates: MAX15020 Revision History