Evaluates: MAXM17545 in 3.3V MAXM17545 3.3V Output Output-Voltage Application Evaluation Kit General Description Features The MAXM17545 evaluation kit (EV kit) is a demonstration Highly Integrated Solution with Integrated Shield Inductor circuit of MAXM17545 high-voltage, high-efficiency, current Wide 4.5V to 42V Input Range mode scheme, synchronous step-down DC-DC switching Preset 3.3V Output with a Fixed Resistor-Divider on power module. The EV kit is designed for a 3.3V output FB (Feedback Pin) and delivers up to 1.7A load current from a wide input- Programmable Output-Voltage Feature (0.9V to 12V) voltage range of 4.5V to 42V. The EV kit switches at an optimal 400kHz switching frequency to allow the use of Up to 1.7A Output Current small component-sizes, helping to minimize solution-size High 91.2% Efficiency (V = 12V, V = 3.3V at 0.73A) IN OUT while maintaining high-performance. The EV kit provides 400kHz Switching Frequency a precision-enable input, an open-drain RESET output signal, and external frequency synchronization to provide Enable/UVLO Input, Resistor-Programmable UVLO a simple and reliable startup sequence and eliminate beat Threshold frequency between regulators. The EV kit also includes Adjustable Soft-Start Time optional component footprints to program different output Selectable PWM, PFM, or DCM Mode voltages, an adjustable input undervoltage-lockout, and a soft-start time to control inrush current during startup. The Open-Drain RESET Output MAXM17545 IC data sheet provides a complete descrip- External Frequency Synchronization tion of the part that should be read in conjunction with this Overcurrent and Overtemperature Protection data sheet prior to modifying the demo circuit. Low-Profile, Surface-Mount Components Lead(Pb)-Free and RoHS Compliant Ordering Information appears at end of data sheet. Fully Assembled and Tested 19-7617 Rev 0 5/15Evaluates: MAXM17545 in 3.3V MAXM17545 3.3V Output Evaluation Kit Output-Voltage Application components are included to ease board modification for Quick Start different input/output configurations. Recommended Equipment Soft-Start Input (SS) MAXM17545 EV kit The device utilizes an adjustable soft-start function to 4.5V to 42V DC power supply (V ) IN limit inrush current during startup. The soft-start time is Dummy load capable of sinking 1.7A programmed by the value of the external capacitor from Digital voltmeter (DVM) SS to GND (C1). The selected output capacitance (C ) SEL 100MHz dual-trace oscilloscope and the output voltage (V ) determine the minimum OUT value of C1, as shown by the following equation: Procedure 3 C128 10 C V The EV kit is fully assembled and tested. Follow the steps SEL OUT below to verify board operation. Caution: Do not turn on where C1 is in nF and C is in F the power supply until all connections are completed. SEL The soft-start time (t ) is calculated by the equation 1) Set the power supply at a voltage between 4.5V and SS 42V. Disable the power supply. below: t = C1/ 5.55 2) Connect the positive and negative terminals of the SS power supply to IN and PGND PCB pads, respectively. where t is in ms and C1 is in nF. SS 3) Connect the positive and negative terminals of the Programmable Undervoltage-Lockout (UVLO) 1.7A load to OUT and PGND2 PCB pads, respectively, and set the load to 0A. The EV kit offers an adjustable input undervoltage- lockout level by resistor dividers connected between IN, 4) Connect the DVM across the OUT PCB pad and the EN/UVLO, and GND pins. For normal operation, a shunt PGND2 PCB pad. should not be installed across pins 1-2 on JU1 to enable 5) Verify that no shunts are installed across pins 1-2 on the output through an internal pullup 3.3M resistor from jumper JU1 to enable UVLO (see Table 1 for details). EN/UVLO pin to IN pin. To disable the output, install the 6) Verify that a shunt is installed across JU3 to disable shunt across pins 1-2 on JU1 to pull EN/UVLO pin to the external synchronization (see Table 3 for details). GND. See Table 1 for JU1 jumper setting details. The 7) Verify that a shunt is installed across JU2 to enable EV kit also provides an optional R3 PCB footprint to PWM mode (see Table 2 for details). program a UVLO threshold voltage at which an input- 8) Enable the input power supply. voltage level device turns on. The R3 resistor can be calculated by the following equation: 9) Verify the DVM displays 3.3V. 10) Increase the load up to 1.7A to verify the DVM 4009.5 R3 = continues displaying 3.3V. (V 1.215) INU Detailed Description of Hardware where V is the input voltage at which the device is INU The EV kit is a proven circuit to demonstrate the high- required to turn on, and R3 unit is in k. voltage, high-efficiency, and compact solution-size of the synchronous step-down DC-DC power module. The Table 1. UVLO Enable/Disable output voltage is preset for 3.3V to operate from 4.5V to Configuration (JU1) 42V and provides up to 1.7A load current. The optimal fre- quency is set at 400kHz to maximize efficiency and minimize SHUNT MAXM17545 EN PIN component size. The EV kit includes JU1 to enable/disable POSITION OUTPUT UVLO of the device, JU2 to configure in PWM, PFM, or Installed Connected to GND Disable DCM mode to improve light-load efficiency, and JU3 to Not installed* Connected to VIN Enable enable/disable external clock synchronize (SYNC). The RESET PCB pad is also available for monitoring output *Default position. voltage regulation to enable/disable the application circuit of the load. The electrolytic capacitor (C8) is required only when the V power supply is situated far from device IN circuit. On the bottom layer, additional footprints of optional Maxim Integrated 2 www.maximintegrated.com