Evaluates: MAXM17574 MAXM17574 5V Output 5V Output Application Evaluation Kit General Description Quick Start The MAXM17574 5V-output evaluation kit (EV kit) Recommended Equipment provides a proven design to evaluate the MAXM17574 One 10V to 60V DC, 2A Power Supply high-voltage, high-efficiency, synchronous step-down One 15W resistive load with 3A sink capacity DC-DC converter. The EV kit is preset for 5V output at load currents up to 3A and features a 650kHz switching Four digital multimeters (DMM) frequency for optimum efficiency and component size. One MAXM17574EVKITA EV kit The EV kit features an adjustable input undervoltage lock- out, adjustable soft-start, open-drain RESET signal, and Equipment Setup and Test Procedure external frequency synchronization. The MAXM17574 The EV kit is fully assembled and tested. Follow the steps module data sheet provides a complete description of the below to verify board operation. part that should be read in conjunction with this data sheet Caution: Do not turn on power supply until all connec- prior to operating the EV kit. For full module features, ben- tions are complete. efits and parameters for the IC, refer to the MAXM17574 1) Set the input power supply at a voltage between 10V data sheet. and 60V. Disable the power supply. Features 2) Connect the positive terminal of the input power sup- Highly Integrated Solution with Built-In Shielded ply to the V PCB pad and the negative terminal IN EMI Inductor to the nearest PGND pad. Connect the positive termi- nal of the 3A load to the V pad and the negative OUT Wide 10V to 60V Input Range terminal to the nearest PGND pad. Programmed 5V Output, Up To 3A Output Current 3) Connect a DVM (DMM in voltage measurement High 93% Efficiency (V = 12V, V = 5V at 1.0A) IN OUT mode) across the V pad and the nearest PGND OUT 650kHz Switching Frequency pad. EN/UVLO Input, Resistor-Programmable UVLO 4) Verify that shunts are not installed on jumper J1 (see Threshold Table 1 for details). Programmed 4ms Soft-Start Time 5) Select the shunt position on jumper J2 according to the intended mode of operation (see Table 2 for Selectable PWM And DCM Modes details). Open-Drain RESET Output Pulled Up To 5V V CC 6) Turn on the input power supply. Provision for External Frequency Synchronization 7) Enable the load. Overcurrent and Overtemperature Protection 8) Verify that the DVM displays 5V across the output Low-Profile, Surface-Mount Components terminals. Proven PCB Layout Ordering Information appears at end of data sheet. Fully Assembled and Tested CISPR-22 Class B Compliant 319-100078 Rev 0 9/17Evaluates: MAXM17574 MAXM17574 5V Output Evaluation Kit 5V Output Application Adjusting Output Voltage Detailed Description The MAXM17574 module supports an adjustable output The MAXM17574 EV kit is designed to demonstrate the voltage range, from 0.9V to 15V, using a feedback resis- salient features of the MAXM17574 power module. The tive divider from OUT to FB. To get different output volt- EV kit includes an EN/UVLO pad and jumper J1 to enable ages, refer to Table 1. Selection of Components in the the output at a desired input voltage. The MODE/SYNC MAXM17574 data sheet. R5 and R6 of the EV kit corre- pad allows an external clock interface to synchronize the spond to RU and RB in Table 1. Selection of Components device. Jumper J2 allows selection of a particular mode of of the MAXM17574 data sheet. operation based on light-load performance requirements. An additional RESET pad is available for monitoring if the Soft-Start Programming converter output voltage is in regulation. The MAXM17574 offers an adjustable soft-start function On the bottom layer of the EV kit, additional footprints to limit inrush current during startup. The soft-start time is for optional components are included to ease board adjusted by changing the value of C4, the external capaci- modification for different input and output configurations. tor from the SS pin to SGND. The capacitance required Placeholders are also available on the bottom layer for for a given soft-start time (t ) is given by the following SS installation of EMI filter components. EMI component val- equation: ues are provided in the schematic. -6 C4 = 5.55 x 10 x t SS Setting the Switching Frequency The capacitor required for a 4ms soft-start time is Selection of switching frequency must consider input- calculated to be 22nF. voltage range, desired output voltage, t , and ON(MIN) Enable/Undervoltage-Lockout (EN/UVLO) t of the MAXM17574. To optimize efficiency OFF(MIN) Programming and component size, a switching frequency of 650kHz is chosen for 5V-programmed output. Resistor R2 con- The MAXM17574 module offers an adjustable input nected between RT and SGND pins, programs the undervoltage-lockout feature. In this EV kit, for normal desired switching frequency. Using Table 1. Selection of operation, leave jumper J1 open. To disable the output, Components in the MAXM17574 data sheet, choose R2 install a jumper across pins 1-2 on J1. See Table 1 for J1 to be 30.1k. Table 1. Selection of Components recom- settings. Resistor R1 connected from EN/UVLO to SGND mends optimized switching frequency for various output sets the input voltage (V ) at which the device turns on. INU designs. The value of resistor R1 is calculated as follows: Input Capacitor Selection 4009.5 R1 The input capacitor serves to reduce the current peaks ( V 1.215 ) INU drawn from the input power supply and also reduce where R1 is in k. switching frequency voltage ripple at the input. Table 1. Selection of Components in the MAXM17574 data sheet For the MAXM17574 to turn on at a 9.5V input, the R1 summarizes the choice of input capacitor for various resistor is calculated to be 487k. requirements. Using this table, the input capacitor (C2) for MODE Selection (MODE/SYNC) this EV kit is chosen to be 4.7F/80V. The MODE/SYNC pin can be used to select between Output Capacitor Selection PWM and DCM modes of operation. The logic state of X7R ceramic output capacitors are preferred due to their the MODE/SYNC pin is latched when V and EN/UVLO CC stability over temperature in industrial applications. Table voltages exceed their respective rising thresholds, and all 1. Selection of Components in the MAXM17574 data internal voltages are ready to allow LX switching. State sheet summarizes the choice of output capacitor for vari- changes on the MODE/SYNC pin are ignored during ous requirements. Using this table, the output capacitor normal operation. Refer to the MAXM17574 module data (C8) for this EV kit is chosen to be 47F/6.3V. sheet for more information on the PWM and DCM modes of operation. Table 2 shows EV kit jumper settings that can be used to configure the desired mode of operation. Maxim Integrated 2 www.maximintegrated.com