Evaluates: MAXM17503 in MAXM17503 5V 5V Output-Voltage Application Output Evaluation Kit General Description Features The MAXM17503 evaluation kit (EV kit) is a demonstration Highly Integrated Solution with Integrated Shield circuit of the MAXM17503 high-voltage, high-efficiency, Inductor current-mode scheme, synchronous step-down DC-DC Wide 11V to 60V Input Range switching power module. The EV kit is designed for a 5V Preset 5V Output with a Fixed Resistor-Divider on output and delivers up to a 2.5A load current from a wide the Feedback Pin (FB) input voltage range of 11V to 60V. The EV kit switches at an optimal 500kHz switching frequency to allow the use of Programmable Output-Voltage Feature (0.9V to 12V) small component sizes, helping to minimize solution size Up to 2.5A Output Current while maintaining high performance. The EV kit provides High 93% Efficiency (V = 12V, V = 5V at 1.0A) IN OUT a precision-enable input, an open-drain RESET output 500kHz Switching Frequency signal, and external frequency synchronization to provide a simple and reliable startup sequence and eliminate beat Enable/UVLO Input, Resistor-Programmable UVLO frequency between regulators. The EV kit also includes Threshold optional component footprints to program different output Adjustable Soft-Start Time voltages, an adjustable input undervoltage lockout, and a Selectable PWM, PFM, or DCM Mode soft-start time to control inrush current during startup. The MAXM17503 IC data sheet provides a complete descrip- Open-Drain RESET Output tion of the part that should be read in conjunction with this External Frequency Synchronization data sheet prior to modifying the demo circuit. Overcurrent and Overtemperature Protection Ordering Information appears at end of data sheet. Low-Profile, Surface-Mount Components Lead(Pb)-Free and RoHS Compliant Fully Assembled and Tested Proven PCB Layout 19-7624 Rev 0 5/15Evaluates: MAXM17503 in MAXM17503 5V Output Evaluation Kit 5V Output-Voltage Application situated far from device circuit. When R4 is open, Quick Start the device switches at a 500kHz switching frequency. Recommended Equipment On the bottom layer, additional footprints of optional MAXM17503 EV kit components are included to ease board modification for different input/output configurations. 11V to 60V DC power supply (V ) IN Dummy load capable of sinking 2.5A Soft-Start Input (SS) Digital voltmeter (DVM) The device utilizes an adjustable soft-start function to limit inrush current during startup. The soft-start time is 100MHz dual-trace oscilloscope programmed by the value of the external capacitor from Procedure SS to GND (C1). The selected output capacitance (C ) SEL The EV kit is fully assembled and tested. Follow the steps and the output voltage (V ) determine the minimum OUT below to verify board operation. Caution: Do not turn on value of C1, as shown by the following equation: the power supply until all connections are completed. 3 C128 10 C V SEL OUT 1) Set the power supply at a voltage between 11V and 60V. Disable the power supply. where C1 is in nF and C is in F SEL 2) Connect the positive and negative terminals of the The soft-start time (t ) is calculated by the equation SS power supply to IN and PGND PCB pads, respectively. below: 3) Connect the positive and negative terminals of the t = C1/ 5.55 SS 2.5A load to OUT and PGND2 PCB pads, respectively, and set the load to 0A. where t is in ms and C1 is in nF. SS 4) Connect the DVM across the OUT PCB pad and the Programmable Undervoltage Lockout (UVLO) PGND2 PCB pad. The EV kit offers an adjustable input undervoltage- 5) Verify that no shunts are installed across pins 1-2 on lockout level by resistor-dividers connecting between jumper JU1 to enable UVLO (see Table 1 for details). the IN, EN/UVLO, and GND pins. For normal operation, 6) Verify that a shunt is installed across JU3 to disable a shunt should not be installed across pins 1-2 on JU1 external synchronization (see Table 3 for details). to enable the output through an internal pullup 3.3M resistor from the EN/UVLO to IN pins. To disable the 7) Verify that a shunt is installed across JU2 to enable output, install the shunt across pins 1-2 on JU1 to pull the PWM mode (see Table 2 for details). EN/UVLO pin to GND. See Table 1 for JU1 setting details. 8) Enable the input power supply. The EV kit also provides an optional R3 PCB footprint 9) Verify the DVM displays 5V. to program a UVLO threshold voltage at which an input- 10) Increase the load up to 2.5A to verify the DVM continues voltage-level device turns on. The R3 resistor can be displaying 5V. calculated by the following equation: 4009.5 Detailed Description of Hardware R3 = (V 1.215) The MAXM17503 EV kit is a proven circuit to demonstrate the INU high-voltage, high-efficiency, and compact solution-size where V is the input voltage at which the device is INU of the synchronous step-down DC-DC power module. required to turn on, and R3 unit is in k. The output voltage is preset for 5V to operate from 11V to 60V and provides up to 2.5A load current. The optimal frequency is set at 500kHz to maximize effi- Table 1. UVLO Enable/Disable ciency and minimize component size. The EV kit includes Configuration (JU1) JU1 to enable/disable UVLO of the device, JU2 to configure in PWM, PFM, or DCM mode to improve light- SHUNT MAXM17503 EN PIN load efficiency, and JU3 to enable/disable external clock POSITION OUTPUT synchronization (SYNC). The RESET PCB pad is also avail- Installed Connected to GND Disable able for monitoring output-voltage regulation to enable/ Not installed* Connected to VIN Enable disable the application circuit of the load. The electrolytic capacitor (C8) is required only when the V power supply is *Default position. IN Maxim Integrated 2 www.maximintegrated.com