Click here for production status of specific part numbers. Evaluates: MAXM17906 1.8V MAXM17906 1.8V Output Output-Voltage Application Evaluation Kit General Description Quick Start The MAXM17906 1.8V output evaluation kit (EV kit) Recommended Equipment provides a proven design to evaluate the MAXM17906 One 4.5V to 24V DC, 300mA power supply high-voltage, high-efficiency, synchronous step-down 0.5W resistive load with 300mA sink capacity DC-DC module. The EV kit is programmed to deliver 1.8V output for loads up to 300mA. The EV kit features an Four digital multimeters (DMM) adjustable input undervoltage lockout, selectable mode, MAXM17906EVKIT and open-drain RESET signal. The MAXM17906 data sheet provides a complete description of the module that Equipment Setup and Test Procedure should be read in conjunction with this EV kit data sheet The EV kit is fully assembled and tested. Follow the steps prior to modifying the demo circuit. For full module fea- below to verify the board operation. tures, benefits and parameters, refer to the MAXM17906 Caution: Do not turn on power supply until all data sheet. connections are completed. 1) Set the power supply at a voltage between 4.5V and Features 24V. Then, disable the power supply. Highly Integrated Solution 2) Connect the positive terminal of the power supply to Wide 4.5V to 21.5V Input Range the VIN PCB pad and the negative terminal to the Programmed 1.8V Output, Delivers Up To 300mA nearest GND PCB pad. Connect the positive termi- Output Current nal of the 300mA load to the VOUT PCB pad and the High 78.93% Efficiency negative terminal to the nearest GND PCB pad. (V = 12V, V = 1.8V at 100mA) IN OUT 3) Connect the DVM (DMM in voltage-measurement 550kHz Switching Frequency mode) across the VOUT PCB pad and the nearest GND PCB pad. ENABLE/UVLO Input, Resistor-Programmable UVLO Threshold 4) Verify that shunt is not installed on jumper J1 (see Table 1 for details). PFM Feature for Better Light-Load Efficiency 5) Turn on the DC power supply. Fixed Internal 3.75ms Soft-Start Time 6) Enable the load. RESET Output, with Pullup Resistor to V CC 7) Verify that the DVM displays 1.8V. Overcurrent and Overtemperature Protection (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 319-100389 Rev 0 6/19Evaluates: MAXM17906 1.8V MAXM17906 1.8V Output Evaluation Kit Output-Voltage Application For MAXM17906 to turn on at 4.5V input, the Resistor R2 Detailed Description is calculated to be 825k. The MAXM17906 EV kit is designed to demonstrate salient features of MAXM17906 power module. The EV kit Input Capacitor Selection includes an EN/UVLO PCB pad, and jumper J1, to enable The input capacitor serves to reduce the current peaks the output at a desired input voltage. Jumper J2 allows drawn from the input power supply and reduces switching selection of either PWM or PFM mode of operation based frequency ripple at the input. The input capacitance must on light-load performance requirements. An additional be greater than or equal to the value given in Table 1 of RESET pad is available for monitoring if the converter MAXM17906 data sheet. Input capacitor C3 is chosen to output voltage is in regulation. be 1F/50V. Output Capacitor Selection Electromagnetic Interference (EMI) X7R ceramic output capacitors are preferred due to their Compliance to conducted emissions (CE) standards stability over temperature in industrial applications. The requires an EMI filter at the input of a switching power required output capacitor (C5) for 1.8V output is selected converter. The EMI filter attenuates high-frequency cur- from Table 1 of the MAXM17906 data sheet as 10F/6.3V. rents drawn by the switching power converter and limits the noise injected back into the input power source. Adjusting Output Voltage Use of EMI filter components as shown in Figure 1 in con- The MAXM17906 supports an adjustable output-voltage range, from 0.9V to 6.3V, using a feedback resistive divid- junction with the schematic results in lower conducted emis- sions below CISPR22 Class B limits. The MAXM17906 EV er from V to FB. Output voltage can be programmed OUT using the values given in Table 1 of the MAXM17906 data kit PCB layout is also designed to limit radiated emissions from switching nodes of the power converter resulting in sheet. For 1.8V output, R3 is chosen as 75k, and R4 is chosen as 75k. radiated emissions below CISPR22 Class B limits. Enable/Undervoltage-Lockout (EN/UVLO) Programming The MAXM17906 offers an adjustable input undervoltage- VIN EMI VIN lockout feature. In this EV kit, for normal operation, leave jumper J1 open. When J1 is left open, the MAXM17906 VIN EMI L 1 is enabled when the input voltage rises above 4.5V. To 82H disable MAXM17906, install a jumper across pins 2-3 on C9 C 7 C8 J1. See Table 1 for J1 settings. A potential divider formed 1F 0.1F 0.47F by R1 and R2 sets the input voltage (V ) at which the INU module is enabled. The value of resistor R1 is chosen to be 2.2M, and R2 is calculated using the following equation: Figure 1. EMI Filter Components R 1.215 1 R = 2 (V 1.215) INU where R1 and R2 are in k, Table 1. UVLO Enable/Disable Configuration (J1) POSITION EN/UVLO PIN MAXM17906 OUTPUT Connected to the center node of resistor-divider Programmed to startup at desired input-voltage Not Installed* R1 and R2. level. 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