Evaluates: MAXM17575 MAXM17575 5V Output 5V Output Application Evaluation Kit General Description Quick Start The MAXM17575 5V output evaluation kit (EV kit) pro- Recommended Equipment vides a proven design to evaluate the MAXM17575 high- One 7.5V to 60V DC, 2A power supply voltage, high-efficiency, synchronous step-down DC-DC 7.5W resistive load with 1.5A sink capacity power module. The EV kit is preset for 5V output at load currents up to 1.5A and features a 900kHz switching fre- Four digital multimeters (DMM) quency for optimum efficiency and component size. The One MAXM17575 EVKIT EV kit EV kit features an adjustable input undervoltage lockout, adjustable soft-start, open-drain RESET signal, and exter- Equipment Setup and Test Procedure nal frequency synchronization. The MAXM17575 module The EV kit is fully assembled and tested. Follow the steps data sheet provides a complete description of the part below to verify the board operation. 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 features, benefits tions are completed. and parameters of the MAXM17575 module, refer to the 1) Set the input power supply at a voltage between 7.5V MAXM17575 data sheet. and 60V. Disable the power supply. Features 2) Connect the positive terminal of the power supply to Highly-Integrated Solution with Built-In Shielded the VIN EMI pad and the negative terminal to the Inductor nearest PGND pad. Connect the positive terminal of the 1.5A load to the VOUT pad and the negative Wide 7.5V to 60V Input Range terminal to the nearest PGND pad. Programmed 5V Output, up to 1.5A Output Current 3) Connect a DVM (DMM in Voltage measurement High 92% Efficiency (VIN = 12V, VOUT = 5V at 0.5A) mode) across the VOUT pad and the nearest PGND 900kHz Switching Frequency pad. Enable/UVLO Input, Resistor-Programmable UVLO 4) Verify that shunts are not installed on jumper J1 Threshold (see Table 1 for details). Programmed 1ms Soft-Start Time 5) Turn on the input power supply. PWM Mode of Operation 6) Enable the load. Open-Drain RESET Output 7) Verify that the DVM displays 5V across the output terminals. External Frequency Synchronization Overcurrent and Overtemperature Protection Low-Profile, Surface-Mount Components Proven PCB Layout Fully Assembled and Tested CISPR-22 Class B Compliant Ordering Information appears at end of data sheet. 319-100080 Rev 0 9/17Evaluates: MAXM17575 MAXM17575 5V Output Evaluation Kit 5V Output Application R8 of the EV kit correspond to RU and RB in Table 1 of Detailed Description MAXM17575 data sheet. The MAXM17575 EV kit is designed to demonstrate the salient features of the MAXM17575 power module. Soft-Start Programming The MAXM17575 EV kit includes an EN/UVLO pad and MAXM17575 offers an adjustable soft-start function to jumper J1 to enable the output at a desired input voltage. limit inrush current during startup. In this EV kit SS pin is The RT/SYNC pad allows an external clock interface connected to SS C using short trace to have default 1ms to synchronize the device. An additional RESET pad is soft-start time. The soft-start time can be increased by available for monitoring if the converter output voltage is adding C11, the external capacitor from SS pin to SGND. in regulation. The capacitance required for additional soft-start time On the bottom layer of the EV kit, additional footprints for (t ) is given by the following equation: SS optional components are included to ease board modifica- -6 C11 = 5.55 x 10 x t SS tion for different input/output configurations. Placeholders are also available on the bottom layer for installation of Enable/Undervoltage Lockout EMI filter components. EMI component values are pro- (EN/UVLO) Programming vided in the schematic. The MAXM17575 has an internal pullup resistor (3.3M) from EN/UVLO to VIN to enable a default start up. The Setting the Switching Frequency device offers an adjustable input under voltage lockout Selection of switching frequency must consider input feature. In this EV kit, for normal operation, leave the voltage range and desired output voltage, t and ON(MIN) jumper J1 open. To disable the output, install a jumper t of the MAXM17575. To optimize efficiency OFF(MIN) across pins 1-2 on J1. See Table 1 for J1 settings. and component size, a switching frequency of 900kHz Resistor R3 connected from EN/UVLO to SGND sets the is chosen for the 5V output. Resistor R1, connected input voltage (V ) at which the device should turn on. INU between the RT/SYNC and SGND pins, programs the Value of R3 resistor is calculated as follows: desired switching frequency. Referring to Table 1 in the MAXM17575 data sheet, R1 is chosen to be 21.5k. See 3.3 1.215 R3 Table 1 in the MAXM17575 data sheet to see the various ( V 1.215 ) INU switching frequency recommendations for optimized vari- ous output designs. where R3 is in k. For the MAXM17575 to turn on at 7.0V input, the resistor Input Capacitor Selection (R3) is calculated to be 698k. The input capacitor serves to reduce the current peaks drawn from the input power supply and also reduce External Clock Synchronization switching frequency voltage ripple at the input. Refer to (RT/SYNC) Table 1 in the MAXM17575 data sheet to see the sum- The internal oscillator of the MAXM17575 can be syn- mary of input capacitors choices for various requirements. chronized to an external clock signal through the RT/ Using this table, the input capacitor (C5) for this EV kit is SYNC pin. The external synchronization clock frequency chosen to be 2.2F/100V. must be between 1.1 x f and 1.4 x f , where f is SW SW SW the frequency programmed by the R1 resistor. When an Output Capacitor Selection external clock is applied to the RT/SYNC pin, the inter- X7R ceramic output capacitors are preferred due to nal oscillator frequency synchronizes to external clock their stability over temperature in industrial applications. frequency (from original frequency based on the RT Refer to Table 1 in the MAXM17575 data sheet to see a setting) after detecting 16 external clock edges. The summary of output capacitor choices for various require- minimum external clock high pulse width and amplitude ments. Using this table, the output capacitor (C13) for this should be greater than 50ns and 2.1V, respectively. The EV kit is chosen to be 22F/10V. maximum external clock low pulse amplitude should be less than 0.8V. Adjusting Output Voltage The MAXM17575 supports an adjustable output volt- age range, from 0.9V to 12V, using a feedback resistive divider from OUT to FB. To get different output voltages, refer to Table 1 in the MAXM17575 data sheet. R7 and Maxim Integrated 2 www.maximintegrated.com