Click here for production status of specific part numbers. Evaluates: MAX17633 MAX17633AEVKIT Evaluation Kit 3.3V Output-Voltage Application General Description Quick Start The MAX17633AEVKIT 3.3V output evaluation kit (EV Recommended Equipment kit) provides a proven design to evaluate the MAX17633A One MAX17633AEVKIT EV kit high-voltage, high-efficiency, synchronous step-down One 0V to 36V DC, 5A power supply DC-DC converter. The EV kit is preset for 3.3V output at load currents of 3.5A and features a 500kHz switching Load capable of sinking 3.5A current frequency for optimum efficiency and component size. Digital voltmeter (DVM) 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. EV kit specifications, The EV kit is fully assembled and tested. Follow the steps settings, features and benefits are highlighted. For full below to verify board operation: MAX17633A IC features, benefits and parameters, refer Caution: Do not turn on power supply until all to MAX17633 datasheet. connections are complete. 1) Set the input power supply at a voltage between 4.5V Features and 36V. Disable the power supply. Wide 4.5V to 36V Input Range 2) Connect the positive terminal of the input power Programmed 3.3V Output, 3.5A Load Current supply to the VIN PCB pad and the negative terminal 500kHz Switching Frequency to the nearest PGND pad. Connect the positive EN/UVLO Input, Resistor-Programmable UVLO terminal of the 3.5A load to the VOUT pad and the Threshold negative terminal to the nearest PGND pad. Programmed 1ms Soft-Start Time 3) Connect a DVM across the VOUT pad and the nearest Selectable PWM, PFM, and DCM Modes PGND pad. Open-Drain RESET Output Pulled Up To 5V of 4) Verify that shunts are not installed on jumper JU1 INTVCC (see Table 1 for details). Provision for External Frequency Synchronization 5) Select the shunt position on jumper JU2 according Overcurrent and Overtemperature Protection to the intended mode of operation (see Table 2 for Proven PCB Layout details). Fully Assembled and Tested 6) Turn on the input power supply. 7) Enable the load. 8) Verify that the DVM displays 3.3V. Ordering Information appears at end of data sheet. 319-100197 Rev 1 8/18Evaluates: MAX17633 MAX17633AEVKIT Evaluation Kit 3.3V Output-Voltage Application Enable/Undervoltage-Lockout (EN/UVLO) Detailed Description of Hardware Programming The MAX17633AEVKIT is designed to demonstrate the The device offers an adjustable input undervoltage-lockout salient features of the MAX17633A. The EV kit includes level, where output is enabled at the minimum desired an EN/UVLO pad and jumper JU1 to enable the output at input-voltage level. For always-enable operation, a shunt a desired input voltage. The MODE/SYNC pad allows an should be installed across pins 1-2 on jumper JU1, which external clock interface to synchronize the device. Jumper pulls up the EN/UVLO to VIN. In order to disable the JU2 allows selection of a particular mode of operation output, install a shunt across pins 2-3 on JU1, which pulls based on light-load performance requirements. An addi- down the EN/UVLO pin to VSGND. See Table 1 for JU1 tional RESET pad is available for monitoring the status of settings. Set the input voltage level (input undervoltage- the output voltage. lockout level) above which the device turns on with the Setting the Switching Frequency resistive voltage-divider R1 and R2 connected between Switching frequency selection must consider input-voltage VIN and SGND. range, desired output voltage, t , and t of ON(MIN) OFF(MIN) Choose R1 to be 3.32M and then calculate R2 as the MAX17633A and ambient temperature. To optimize follows: converter size and efficiency of the EV kit, a switching fre- 4033.8 quency of 500kHz is chosen for 3.3V-programmed output. R2 Resistor R5 connected between RT and SGND pins, pro- (V 1.215) INU grams the desired switching frequency. R5 resistor is kept open for a default 500kHz switching frequency. To program where V is the input voltage at that the device requires INU the switching frequency, the R5 resistor is calculated as to turn on. follows: 21000 Table 1. Regulator Enable (EN/UVLO) R5 1.7 f SW Description (JU1) where R5 is in k and f is in kHz. SW SHUNT MAX17633A EV KIT EN/UVLO PIN Soft-Start Programming POSITION OUTPUT The EV kit offers an adjustable soft-start function to 1-2 Connected to VIN Enabled limit inrush current during startup. The soft-start time Connected to the is adjusted by changing the value of C3, the external Enabled, UVLO level Not center node of set through the capacitor from the SS pin to SGND. The selected output Installed* resistor-divider R1 R1 and R2 resistors capacitance (C ) and the output voltage (V ) SEL OUT and R2 determine the minimum value of C3, as shown by the 2-3 Connected to SGND Disabled following equation: *Default position -6 C3 28 x 10 x C x V SEL OUT The soft-start time (t ) is related to the soft-start capaci- SS tor C3 by the following equation: C3 t = SS 6 5.55 10 For example, in order to program a 1ms soft-start time, C3 should be 5600pF. Maxim Integrated 2 www.maximintegrated.com =