Evaluates: MAXM17543 in 3.3V MAXM17543 3.3V Output Output-Voltage Application Evaluation Kit General Description Features The MAXM17543 evaluation kit (EV kit) is a demonstration Highly Integrated Solution with Integrated Shield circuit of MAXM17543 high-voltage, high-efficiency, Inductor current-mode scheme, synchronous step-down DC-DC Wide 4.5V to 42V Input Range switching power module. The EV kit is designed for a 3.3V Preset 3.3V Output with a Fixed Resistor-Divider on output and delivers up to 2.5A load current from a wide FB (Feedback Pin) input-voltage range of 4.5V to 42V. 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 91.2% Efficiency (V = 12V, V = 3.3V at IN OUT a precision-enable input, an open-drain RESET output 0.74A) signal, and external frequency synchronization to provide 500kHz Switching Frequency a simple and reliable startup sequence and eliminate beat frequency between regulators. The EV kit also includes Enable/UVLO Input, Resistor-Programmable UVLO optional component footprints to program different output Threshold voltages, an adjustable input undervoltage-lockout, and a Adjustable Soft-Start Time soft-start time to control inrush current during startup. The Selectable PWM, PFM, or DCM Mode MAXM17543 IC data sheet provides a complete description of the part and should be read in conjunction with this data Open-Drain RESET Output sheet prior to modifying the demonstration circuit. External Frequency Synchronization Overcurrent and Overtemperature Protection Low-Profile, Surface-Mount Components Lead(Pb)-Free and RoHS Compliant Fully Assembled and Tested Ordering Information appears at end of data sheet. 19-7616 Rev 0 5/15Evaluates: MAXM17543 in 3.3V MAXM17543 3.3V Output Evaluation Kit Output-Voltage Application electrolytic capacitor (C8) is required only when the V IN Quick Start power supply is situated far from the MAXM17543 circuit. Recommended Equipment When R4 is open, the device switches at 500kHz switching MAXM17543 EV kit frequency. On the bottom layer, additional footprints of optional components are included to allow for easy board 4.5V to 42V DC power supply (V ) IN modification for different input/output configurations. Dummy load capable of sinking 2.5A Soft-Start Input (SS) Digital voltmeter (DVM) The device utilizes an adjustable soft-start function to 100MHz dual-trace oscilloscope limit inrush current during startup. The soft-start time is Procedure programmed by the value of the external capacitor from SS to GND (C1). The selected output capacitance (C ) The EV kit is fully assembled and tested. Follow the steps SEL and the output voltage (V ) determine the minimum below to verify board operation. Caution: Do not turn on OUT value of C1, as shown by the following equation: the power supply until all connections are completed. 1) Set the power supply at a voltage between 4.5V and 3 C128 10 C V SEL OUT 42V. Disable the power supply. where C1 is in nF and C is in F 2) Connect the positive and negative terminals of the SEL power supply to IN and PGND PCB pads, respectively. The soft-start time (t ) is calculated by the equation below: SS 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-lock- 5) Verify that no shunts are installed across pin 1-2 on out level by resistor-dividers connected between the IN, jumper JU1 to enable UVLO (see Table 1 for details). EN/UVLO, and GND pins. For normal operation, a shunt 6) Verify that a shunt is installed across JU3 to disable should not be installed across pins 1-2 on JU1 to enable the external synchronization (see Table 3 for details). the output through an internal pullup 3.3M resistor from the EN/UVLO pin to the IN pin. To disable the output, 7) Verify that a shunt is installed across JU2 to enable install the shunt across pins 1-2 on JU1 to pull EN/UVLO PWM mode (see Table 2 for details). pin to GND. See Table 1 for JU1 jumper setting details. 8) Enable the input power supply. The EV kit also provides an optional R3 PCB footprint 9) Verify the DVM displays 3.3V. to program a UVLO threshold voltage at which an input- voltage level device turns on. The R3 resistor can be 10) Increase the load up to 2.5A to verify the DVM continues displaying 3.3V. calculated by the following equation: 4009.5 Detailed Description of Hardware R3 = (V 1.215) INU The EV kit is a proven circuit to demonstrate the 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 3.3V to operate from 4.5V to 42V and provides up to 2.5A load current. The optimal frequency is set at 500kHz to maximize efficiency and minimize component size. The EV kit includes JU1 to enable/disable UVLO of the device, JU2 to configure in PWM, PFM, or DCM mode to improve light-load efficiency, and JU3 to enable/disable external clock synchronization (SYNC). The RESET PCB pad is also available for monitoring output-voltage regulation to enable/disable the application circuit of the load. The Maxim Integrated 2 www.maximintegrated.com