Click here to ask about the production status of specific part numbers. Evaluates: MAX17783C MAX17783CEVKITB in 5V Output-Voltage Application Evaluation Kit General Description Quick Start The MAX17783CEVKITB evaluation kit (EV kit) provides a Recommended Equipment proven design to evaluate the MAX17783C high-efficiency, MAX17783CEVKITB high-voltage, Himalaya step-down DC-DC converter. The 6.5V to 60V, 3A DC input power supply EV kit generates 5V output at load currents up to 2.5A from a 6.5V to 60V input supply. The switching frequency of the Load capable of sinking 2.5A EV kit is preset to 500kHz for optimum efficiency and com - 2 digital voltmeters (DVM) ponent size. The EV kit features adjustable input under- voltage lockout, adjustable soft-start, open-drain RESET Equipment Setup and Test Procedure signal, and external clock synchronization. The EV kit also The EV kit is fully assembled and tested. Follow the steps provides a good layout example, which is optimized for below to verify board operation. conducted, radiated EMI, and thermal performance. For Caution: Do not turn on the power supply until all more details about the IC benefits and features, refer to connections are completed. the MAX17783C IC data sheet. 1) Set the power supply at a voltage between 6.5V and 60V. Disable the power supply. Features Operates from a 6.5V to 60V Input Supply 2) Connect the positive terminal of the power supply 5V Output Voltage to the VIN PCB pad and the negative terminal to the nearest PGND PCB pad. Connect the positive Delivers Up to 2.5A Output Current terminal of the 2.5A load to the VOUT PCB pad and the 500kHz Switching Frequency negative terminal to the nearest PGND PCB pad. Enable/UVLO Input, Resistor-Programmable UVLO Threshold 3) Connect one DVM across the VOUT PCB pad and the nearest PGND PCB pad. Adjustable Soft-Start Time External Clock Synchronization 4) Verify that shunts are not installed across the pins on Open-Drain RESET Output jumper JU1 (see Table 1 for details). Overcurrent and Overtemperature Protection 5) Turn on the DC power supply. Proven PCB Layout 6) Enable the load. Fully Assembled and Tested 7) Ensure that input voltage to be 6.5V or higher, with Complies with CISPR32(EN55032) Class B which EN/UVLO voltage is more than EN/UVLO ris- Conducted and Radiated Emissions ing threshold. 8) Verify that the DVM displays 5V. 9) Connect the other DVM across the RESET pad and Ordering Information appears at end of data sheet. GND. Verify that the DVM displays 5V. 10) The power supply voltage can be set at any voltage between 6.5V and 60V. 11) Reduce the input voltage to 5V which is below the EN/UVLO falling threshold. 12) Verify that the DVM across the VOUT PCB pad and the nearest PGND PCB pad displays 0V. 13) Verify that the DVM across the RESET pad and the nearest GND pad displays 0V. 14) Disable the input power supply. 319-100566 Rev 1 3/21Evaluates: MAX17783C MAX17783CEVKITB Evaluation Kit in 5V Output-Voltage Application External Clock Synchronization (RT/SYNC) Detailed Description The EV kit provides a RT/SYNC PCB pad to synchronize The MAX17783CEVKITB provides a proven design to the MAX17783C to an optional external clock. For more evaluate the MAX17783C high-efficiency, high-voltage, details about external clock synchronization, refer to the Himalaya step-down DC-DC converter. The EV kit gener- MAX17783C data sheet. ates 5V output at load currents up to 2.5A from a 6.5V to 60V input supply. The EV kit features a 500kHz switching Active-Low, Open-Drain Reset Output (RESET) frequency for optimum efficiency and component size. The EV kit provides a RESET PCB pad to monitor the The EV kit includes an EN/UVLO PCB pad and JU1 to status of the converter. RESET goes high enable the output at a desired input voltage or enable the 1024 switching cycles after V rises above OUT converter through an external enable signal on the EN/ 95% (typ) of its nominal regulated output UVLO PCB pad. The RT/SYNC PCB pad allows applica- voltage. RESET goes low when V falls below 92% OUT tion of an external clock to synchronize the device. An (typ) of its nominal regulated voltage. additional RESET PCB pad is available for monitoring Hot Plug-In and Long Input Cables whether the converter output is in regulation. The MAX17783CEVKITB PCB layout provides an optional Soft-Start Input (SS) electrolytic capacitor (C6 = 33F/100V). This capacitor limits The EV kit offers an adjustable soft-start function to the peak voltage at the input of the MAX17783C when limit inrush current during startup. The soft-start time is the DC input source is Hot-Plugged to the EV kit input adjusted by the value of external soft-start capacitor (C11) terminals with input cables. The equivalent series resistance connected between SS and GND pins. The selected output (ESR) of the electrolytic capacitor dampens the oscillations capacitance (C ) and the output voltage (V ) determine SEL OUT caused by interaction of the inductance of the long input the minimum required soft-start capacitor as follows: cables, and the ceramic capacitors at the buck converter -6 C 28 x 10 x C x V input. SS SEL OUT The soft-start time (t ) is related to the capacitor Electromagnetic Interference (EMI) SS connected at SS (C ) by the following equation: Compliance to conducted emissions (CE) standards SS requires an EMI filter at the input of a switching power C SS converter. The EMI filter attenuates high-frequency t = SS 6 5.55 10 currents drawn by the switching power converter, and limits the noise injected back into the input power source. For example, to program a 1ms soft-start time, a 5600pF The MAX17783CEVKITB PCB has designated footprints capacitor should be connected from the SS pin to GND. for the placement of conducted EMI filter components Enable/Undervoltage-Lockout as per the optional Bill of Material (BoM). Use of these (EN/UVLO) Programming filter components results in lower conducted EMI, below The MAX17783C offers an Enable and adjustable CISPR32 Class B limits. Cut open the trace input undervoltage lockout feature. In this EV kit, for at L2 before installing conducted EMI filter normal operation, leave the EN/UVLO jumper (JU1) components. The MAX17783CEVKITB PCB layout is open. When JU1 is left open, the MAX17783C is enabled also designed to limit radiated emissions from switching when the input voltage rises above 6.4V. To disable the nodes of the power converter resulting in radiated emis- MAX17783C, install a jumper across pins 12 on JU1. sions below CISPR32 Class B limits. See Table 1 for JU1 settings. The EN/UVLO PCB pad on the EV kit supports external Enable/Disable control of the Table 1. Converter EN/UVLO Jumper device. Leave JU1 open when external Enable/Disable (JU1) Settings control is desired. A potential divider formed by R1 and R2 sets the input voltage (V ) above which the converter is INU SHUNT enabled when JU1 is left open. EN/UVLO PIN OUTPUT POSITION Choose R1 to be 3.32M (max), and then calculate R2 Connected to the Enabled, UVLO level as follows: Not center node of is set by the 1.218 R1 installed* resistor-divider R1 resistor-divider R2 = and R2 between IN and GND V 1.218 ( ) INU 12 Connected to GND Disabled where, V is the voltage at which the device is required INU *Default position. to turn on. For more details about setting the undervoltage lockout level, refer to the MAX17783C data sheet. Maxim Integrated 2 www.maximintegrated.com