MAX17542G in 3.3V MAX17542G 3.3V Output Output-Voltage Application Evaluation Kit General Description Quick Start The MAX17542G 3.3V EV kit provides a proven design Recommended Equipment to evaluate the MAX17542G 3.3V high-efficiency, high- MAX17542G 3.3V EV kit voltage, synchronous step-down DC-DC converter in 5V to 42V, 2A DC input power supply a TDFN package. The EV kit generates 3.3V at load currents up to 1A from a 5V to 42V input supply. The EV kit Load capable of sinking 1A features a 600kHz fixed switching frequency for optimum Digital voltmeter (DVM) efficiency and component size. The EV kit features a forced- Function generator PWM control scheme that provides constant switching- frequency operation at all load and line conditions. Procedure Features The EV kit is fully assembled and tested. Follow the steps below to verify the board operation. Caution: Do not turn Operates from a 5V to 42V Input Supply on power supply until all connections are completed. 3.3V Output Voltage 1) Set the power supply at a voltage between 5V and 1A Output Current 42V. Disable the power supply. 600kHz Switching Frequency 2) Connect the positive terminal of the power supply to Enable/UVLO Input the VIN PCB pad and the negative terminal to the nearest PGND PCB pad. Connect the positive ter- Resistor-Programmable UVLO Threshold minal of the 1A load to the VOUT PCB pad and the Open-Drain RESET Output negative terminal to the nearest PGND PCB pad. Overcurrent and Overtemperature Protection 3) Connect the DVM across the VOUT PCB pad and Proven PCB Layout the nearest PGND PCB pad. Fully Assembled and Tested 4) Turn on the DC power supply. 5) Enable the load. 6) Verify that the DVM displays 3.3V. Ordering Information appears at end of data sheet. To turn-on/off the part from EN/UVLO, follow the steps below: 1) Connect the power supply to the EV kit and turn on the power supply. Set the power supply at a voltage between 5V and 42V. 2) Connect the function generator output to the EN/ UVLO test loop. 3) EN/UVLO rising threshold is 1.24V and falling threshold is 1.11V. Make sure that the voltage-high and voltage- low levels of the function generator output are greater than 1.24V and less than 1.11V, respectively. 4) While powering down the EV kit, first disconnect the function generator output from the EN/UVLO test loop and then turn off the DC power supply. 19-7656 Rev 0 6/15MAX17542G in 3.3V MAX17542G 3.3V Output Evaluation Kit Output-Voltage Application Regulator Enable/Undervoltage-Lockout Detailed Description of Hardware Level (EN/UVLO) The MAX17542G 3.3V EV kit provides a proven design The device features an EN/UVLO input. For normal to evaluate the MAX17542G 3.3V high-efficiency, high- operation, no shunts should be installed across pins 1-2 voltage, synchronous step-down DC-DC converter in a or 2-3 on jumper JU1. To disable the output, install a shunt TDFN package. The EV kit generates 3.3V at load currents across pins 2-3 on JU1 and the EN/UVLO pin is pulled to up to 1A from a 5V to 42V input supply. The EV kit features GND. See Table 1 for JU1 settings. a 600kHz fixed switching frequency for optimum effi- ciency and component size. The EV kit features a forced- Setting the Undervoltage-Lockout Level PWM control scheme that provides constant switching- The device offers an adjustable input undervoltage- frequency operation at all load and line conditions. lockout level. Set the voltage at which the device turns The EV kit includes an EN/UVLO PCB pad to enable on with a resistive voltage-divider connected from VIN control of the converter output. An additional RESET to GND (see Figure 1). Connect the center node of the PCB pad is available for monitoring the open-drain logic divider to EN/UVLO. output. The VCC PCB pad helps measure the internal Choose R1 to be 3.3M and then calculate R2 as follows: LDO voltage. R1 1.218 Soft-Start Input (SS) R2 = (V 1.218) INU The device utilizes an adjustable soft-start function to limit inrush current during startup. The soft-start time is where V is the voltage at which the device is required adjusted by the value of C3, the external capacitor from INU to turn on. Ensure that V is higher than 0.8 x V . SS to GND. To adjust the soft-start time, determine C3 INU OUT using the following formula: Adjusting the Output Voltage C3 = 5.55 x t SS The device offers an adjustable output voltage. Set the where t is the required soft-start time in milliseconds output voltage with a resistive voltage-divider connected SS and C3 is in nanofarads. from the positive terminal of the output capacitor (V ) OUT to GND (see schematic attached to PDF). Connect the center node of the voltage-divider to FB. To choose the values of R4 and R5, select the parallel combination of R4 and R5, with R less than 15k. Once P R is selected, calculate R4 as follows: P RV P OUT R4 = 0.9 Calculate R5 as follows: R4 0.9 R5 = (V 0.9) OUT Table 1. Regulator Enable (EN/UVLO) Jumper JU1 Settings SHUNT POSITION EV/UVLO PIN MAX17542G 3.3V OUTPUT Connected to the center node of resistor-divider Enabled, UVLO level set through the R1 and R2 Not installed* R1 and R2 resistor-divider 2-3 Connected to GND Disabled *Default position. Maxim Integrated 2 www.maximintegrated.com