Click here for production status of specific part numbers. Evaluates: MAX17574 MAX17574 3.3V Output 3.3V Output-Voltage Application Evaluation Kit General Description Quick Start The MAX17574 3.3V output evaluation kit (EV kit) provides Recommended Equipment a proven design to evaluate the MAX17574 high-voltage, MAX17574 3.3V output EV kit high-efficiency, synchronous step-down DC-DC converter. 5V to 60V, 5A DC input power supply The EV kit is preset for 3.3V output at load currents up to 3A and features a 500kHz switching frequency for Load capable of sinking 3A optimum efficiency and component size. The EV kit Digital voltmeter (DVM) features adjustable input undervoltage lockout, adjustable soft-start, open-drain RESET signal, and external Procedure frequency synchronization. The EV kit is fully assembled and tested. Follow the steps below to verify the board operation. Caution: Do not turn Features on power supply until all connections are completed. Operates from a 5V to 60V Input Supply 1) Set the power supply at a voltage between 5V and 3.3V Output Voltage 60V. Disable the power supply. Up to 3A Output Current 2) Connect the positive terminal of the power supply to the VIN PCB pad and the negative terminal to the 500kHz Switching Frequency nearest PGND PCB pad. Connect the positive Enable/UVLO Input, Resistor-Programmable UVLO terminal of the 3A load to the VOUT PCB pad and the Threshold negative terminal to the nearest PGND PCB pad. Adjustable Soft-Start Time 3) Connect the DVM across the VOUT PCB pad and the MODE/SYNC Pin to Select Among PWM, PFM, or nearest PGND PCB pad. DCM Modes 4) Verify that shunts are installed across pins 1-2 on Open-Drain RESET Output jumper JU1 (see Table 1 for details). External Frequency Synchronization 5) Select the shunt position on jumper JU2 according to the intended MODE/SYNC of operation (see Table 2 Overcurrent and Overtemperature Protection for details). Proven PCB Layout 6) Turn on the DC power supply. Fully Assembled and Tested 7) Enable the load. Ordering Information appears at end of data sheet. 8) Verify that the DVM displays 3.3V. 19-8701 Rev 2 5/18Evaluates: MAX17574 MAX17574 3.3V Output Evaluation Kit 3.3V Output-Voltage Application MODE/SYNC Selection (MODE/SYNC) Detailed Description The devices MODE/SYNC pin can be used to select The MAX17574 3.3V output EV kit provides a proven among PWM, PFM, or DCM modes of operation. The design to evaluate the MAX17574 high-voltage, high- logic state of the MODE/SYNC pin is latched when the efficiency, synchronous step-down DC-DC converter. The V and EN/UVLO voltages exceed the respective UVLO EV kit is preset for 3.3V output from 5V to 60V input at CC rising thresholds and all internal voltages are ready to load currents up to 3A and features a 500kHz switching allow LX switching. State changes on the MODE/SYNC frequency for optimum efficiency and component size. pin are ignored during normal operation. Refer to the The EV kit includes an EN/UVLO PCB pad and jumper MAX17574 IC data sheet for more information on PWM, JU1 to enable the output at a desired input voltage. The PFM, and DCM MODE/SYNC modes of operation. SYNC PCB pad allows an external clock to synchronize Table 2 shows EV kit jumper settings that can be used to the device. Jumper JU2 allows the selection of a particu- configure the desired mode of operation. lar MODE/SYNC of operation based on light-load perfor- mance requirements. An additional RESET PCB pad is External Clock Synchronization available for monitoring whether the converter output is (MODE/SYNC) in regulation. The internal oscillator of the device can be synchronized Soft-Start Input (SS) to an external clock signal on the SYNC pin. The external synchronization clock frequency must be between 1.1f The device utilizes an adjustable soft-start function to SW and 1.4f , where f is the frequency of operation limit inrush current during startup. The soft-start time is SW SW set by R3. The minimum external clock high pulse width adjusted by the value of C8, the external capacitor from should be greater than 50ns and the minimum external SS to GND. The selected output capacitance (C ) and SEL clock low pulse width should be greater than 160ns. the output voltage (V ) determine the minimum value OUT of C8, as shown by the following equation: Table 1. Regulator Enable (EN/UVLO) -6 C8 28 x 10 x C x V SEL OUT Description (JU1) The soft-start time (t ) is related to C8 by the following SS SHUNT equation: EN/UVLO PIN MAX17574 OUTPUT POSITION -6 t = C8/(5.55 x 10 ) SS 1-2* Connected to V Enabled IN For example, to program a 1ms soft-start time, C8 should Connected to the be 5.6nF. Enabled, UVLO level Not center node of set through the R1 and Regulator Enable/Undervoltage-Lockout installed resistor-divider R1 R2 resistors Level (EN/UVLO) and R2 The device offers an adjustable input undervoltage- 2-3 Connected to SGND Disabled lockout level. For normal operation, a shunt should be *Default position. installed across pins 1-2 on jumper JU1. To disable the output, install a shunt across pins 2-3 on JU1 and the EN/ Table 2. MODE/SYNC Description (JU2) UVLO pin is pulled to GND. See Table 1 for JU1 settings. SHUNT MODE/SYNC Set the voltage at which the device turns on with the resis- MAX17574 MODE POSITION PIN tive voltage-divider R1/R2 connected from VIN to SGND. Connect the center node of the divider to EN/UVLO. Not PFM mode of Unconnected installed* operation Choose R1 to be 3.32M and then calculate R2 as follows: PWM mode of 2-3 Connected to SGND R1 1.215 operation R2 = (V 1.215) INU DCM mode of 1-2 Connected to V CC operation where V is the voltage at which the device is required INU *Default position. to turn on. Maxim Integrated 2 www.maximintegrated.com