Click here for production status of specific part numbers. Evaluates: MAX17634C MAX17634CEVKIT Evaluation Kit 5V Output-Voltage Application General Description Quick Start The MAX17634CEVKIT 5V output evaluation kit (EV kit) Recommended Equipment provides a proven design to evaluate the MAX17634C One MAX17634CEVKIT 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 5V output at load currents of 4.25A and features a 400kHz switching Load capable of sinking 4.25A current frequency for optimum efficiency and component size. Digital voltmeter (DVM) The EV kit features an adjustable input undervoltage lockout, adjustable soft-start, open-drain RESET signal, Equipment Setup and Test Procedure and external clock synchronization. EV kit specifications, The EV kit is fully assembled and tested. Follow the steps settings, features and benefits are highlighted. The EV kit below to verify board operation: also provides a good layout example, which is optimized Caution: Do not turn on power supply until all con- for Conducted, Radiated EMI and thermal performance. nections are complete. For more details about the IC benefits and features, refer 1) Set the input power supply at a voltage between 6.5V to the MAX17634 data sheet. and 36V. Disable the power supply. Features 2) Connect the positive terminal of the input power sup- Wide 6.5V to 36V Input Range ply to the VIN PCB pad and the negative terminal to the nearest PGND pad. Connect the positive terminal Programmed 5V Output, 4.25A Load Current of the 4.25A load to the VOUT pad and the negative 400kHz Switching Frequency terminal to the nearest PGND pad. EN/UVLO Input, Resistor-Programmable UVLO 3) Connect a DVM across the VOUT pad and the near- Threshold est PGND pad. Programmed 1ms Soft-Start Time 4) Verify that shunts are not installed on jumper JU1 Selectable PWM, PFM, and DCM Modes (see Table 1 for details). Open-Drain RESET Output Pulled Up To 5V of 5) Select the shunt position on jumper JU2 according INTVCC to the intended mode of operation (see Table 2 for Provision for External Frequency Synchronization details). Overcurrent and Overtemperature Protection 6) Turn on the input power supply. Proven PCB Layout 7) Enable the load. Fully Assembled and Tested 8) Verify that the DVM displays 5V. Complies with CISPR22(EN55022) Class B Conducted and Radiated Emissions 9) Connect the DVM across the RESET pad and SGND. Verify that the DVM displays 5V. 10) Reduce the input voltage to 5V which is below the EN/ UVLO falling threshold. 11) Connect the DVM across the VOUT pad and nearest Ordering Information appears at end of data sheet. PGND. Verify that the DVM displays 0V. 12) Connect the DVM across the RESET pad and SGND. Verify that the DVM displays 0V. 13) Disable the input power supply. 319-100427 Rev 1 9/19Evaluates: MAX17634C MAX17634CEVKIT Evaluation Kit 5V Output-Voltage Application Choose R1 to be 3.32M (max), and then calculate R2 Detailed Description as follows: The MAX17634CEVKIT is designed to demonstrate the salient features of the MAX17634C. The EV kit includes R1 1.215 R2 = an EN/UVLO pad and jumper JU1 to enable the output at (V 1.215) INU a desired input voltage. The Jumper JU2 allows selection of a particular mode of operation based on light load per- where V is the voltage at which the device is required INU formance requirements. The MODE/SYNC pin on jumper to turn on, and R1 and R2 are in k. JU2 allows an external clock interface to synchronize the For more details about setting the undervoltage lockout device. An additional RESET pad is available for monitor- level, refer to the MAX17634 data sheet. ing the status of the output voltage. Mode Selection (MODE) Soft-Start Programming The EV kit provides a jumper (JU2) that allows the The EV kit offers an adjustable soft-start function to MAX17634 to operate in PWM, PFM, and DCM modes. limit inrush current during startup. The soft-start time is Table 2 shows the MODE SELECTION (JU2) settings that adjusted by the value of external soft-start capacitor C3, can be used to configure the desired mode of operation. connected between SS and SGND. The selected output Refer to the MAX17634 data sheet for more details on the capacitance (C ) and the output voltage (V ) deter- SEL OUT modes of operation. mine the minimum value of C3, as shown by the following equation: Table 1. Converter EN/UVLO Jumper -6 C3 28 x 10 x C x V SEL OUT (JU1) Settings The soft-start time (t ) is related to the soft-start capaci- SS tor C3 by the following equation: SHUNT MAX17634C EV KIT EN/UVLO PIN POSITION OUTPUT C3 t = SS 1-2 Connected to VIN Enabled 6 5.55 10 Connected to the Enabled, UVLO level For example, in order to program a 1ms soft-start time, C3 Not center node of set through the should be 5600pF. Installed* resistor-divider R1 R1 and R2 resistors and R2 Enable/Undervoltage-Lockout (EN/UVLO) 2-3 Connected to SGND Disabled Programming *Default position The MAX17634 offers an Enable and adjustable input undervoltage lockout feature. In this EV kit, for normal operation, leave EN/UVLO jumper (JU1) open. When JU1 Table 2. Mode Selection Jumper (JU2) is left open, the MAX17634 is enabled when the input Settings voltage rises above 6.4V. To disable MAX17634, install a jumper across pins 23 on JU1. See Table 1 for JU1 SHUNT MAX17634C EV KIT MODE/SYNC PIN POSITION OUTPUT settings. The EN/UVLO PCB pad on the EV kit supports external Enable/Disable control of the device. Leave JU1 DCM mode of 1-2 Connected to INTVCC open when external Enable/Disable control is desired. A operation potential divider formed by R1 and R2 sets the input volt- PWM mode of age (V ) above which the converter is enabled when INU 2-3* Connected to SGND operation JU1 is left open. Not PFM model of Unconnected Installed operation *Default position Maxim Integrated 2 www.maximintegrated.com