Click here for production status of specific part numbers. Evaluates: MAXM17905 5V MAXM17905 5V Output Output-Voltage Application Evaluation Kit General Description Quick Start The MAXM17905 5V output evaluation kit (EV kit) pro- Recommended Equipment vides a proven design to evaluate the MAXM17905 high- One 4.5V to 24V DC, 300mA power supply voltage, high-efficiency, synchronous step-down DC-DC 1.5W resistive load with 300mA sink capacity module. The EV kit is programmed to deliver 5V output for loads up to 300mA. The EV kit features an adjust- Four digital multimeters (DMM) able input undervoltage lockout, selectable mode, and MAXM17905EVKIT open-drain RESET signal. The MAXM17905 data sheet provides a complete description of the module that should Equipment Setup and Test Procedure be read in conjunction with this EV kit data sheet prior to The EV kit is fully assembled and tested. Follow the steps modifying the demo circuit. For full module features, ben- below to verify the board operation. efits and parameters, refer to the MAXM17905 data sheet. Caution: Do not turn on power supply until all connections are completed. Features 1) Set the power supply at a voltage between 4.5V and Highly Integrated Solution 24V. Then, disable the power supply. Wide 8.5V to 24V Input Range 2) Connect the positive terminal of the power supply to Fixed 5V Output, Delivers Up To 300mA the VIN PCB pad and the negative terminal to the Output Current nearest GND PCB pad. Connect the positive termi- High 85.01% Efficiency nal of the 300mA load to the VOUT PCB pad and the (V = 24V, V = 5V at 150mA) negative terminal to the nearest GND PCB pad. IN OUT 550kHz Switching Frequency 3) Connect the DVM (DMM in voltage-measurement mode) across the VOUT PCB pad and the nearest ENABLE/UVLO Input, Resistor-Programmable UVLO GND PCB pad. Threshold 4) Verify that shunt is not installed on jumper J1 PFM Feature for Better Light-Load Efficiency (see Table 1 for details). Fixed Internal 3.75ms Soft-Start Time 5) Turn on the DC power supply. RESET Output, with Pullup Resistor to V CC 6) Enable the load. Overcurrent and Overtemperature Protection 7) Verify that the DVM displays 5V. (OCP and OTP) Low-Profile, Surface-Mount Components Ordering Information appears at end of data sheet. Proven PCB Layout Fully Assembled and Tested Complies with CISPR22(EN55022) Class B Conducted and Radiated Emissions 319-100388 Rev 0 6/19MAXM17905 5V Output Evaluates: MAXM17905 5V Evaluation Kit Output-Voltage Application Input Capacitor Selection Detailed Description The input capacitor serves to reduce the current peaks The MAXM17905 EV kit is designed to demonstrate drawn from the input power supply and reduces switching salient features of MAXM17905 power module. The EV kit frequency ripple at the input. The input capacitance must includes an EN/UVLO PCB pad, and jumper J1, to enable be greater than or equal to the value given in Table 1 of the output at a desired input voltage. Jumper J2 allows MAXM17905 data sheet. Input capacitor C3 is chosen to selection of either PWM or PFM mode of operation based be 1F/50V. on light-load performance requirements. An additional RESET pad is available for monitoring if the converter Electromagnetic Interference (EMI) output voltage is in regulation. Compliance to conducted emissions (CE) standards Output Capacitor Selection requires an EMI filter at the input of a switching power converter. The EMI filter attenuates high-frequency X7R ceramic output capacitors are preferred due to their currents drawn by the switching power converter and stability over temperature in industrial applications. The limits the noise injected back into the input power source. required output capacitor (C5) for 5V output is selected from Table 1 of the MAXM17905 data sheet as 10F/16V. Use of EMI filter components as shown in Figure 1 in conjunction with the schematic results in lower con- Fixed Output Voltage ducted emissions below CISPR22 Class B limits. The The MAXM17905 is a fixed 5V output module. Connect MAXM17905 EV kit PCB layout is also designed to limit FB of the MAXM17905 directly to VOUT for feedback radiated emissions from switching nodes of the power control. converter resulting in radiated emissions below CISPR22 Class B limits. Enable/Undervoltage-Lockout (EN/UVLO) Programming The MAXM17905 offers an adjustable input undervoltage- lockout feature. In this EV kit, for normal operation, leave jumper J1 open. When J1 is left open, the MAXM17905 VIN EMI VIN is enabled when the input voltage rises above 8.5V. To disable MAXM17905, install a jumper across pins 2-3 on L VIN EMI 1 J1. See Table 1 for J1 settings. A potential divider formed by R1 and R2 sets the input voltage (V ) at which the INU 82H module is enabled. The value of resistor R1 is chosen C C 8 9 C 7 to be 2.2M, and R2 is calculated using the following equation: 1F 0.68F 0.1F R 1.215 1 R = 2 ( V 1.215 ) INU where R1 and R2 are in k. Figure 1. EMI Filter Components For MAXM17905 to turn on at 8.5V input, the Resistor R2 is calculated to be 374k. Table 1. UVLO Enable/Disable Configuration (J1) POSITION EN/UVLO PIN MAXM17905 OUTPUT Connected to the center node of resistor-divider Not Installed* Programmed to startup at desired input-voltage level. R1 and R2. 1-2 Connected to V Enabled if V is greater than V IN IN IN(MIN). 2-3 Connected to GND Disabled *Default position Maxim Integrated 2 www.maximintegrated.com