Click here for production status of specific part numbers. MAX20028 Evaluation Kit Evaluates: MAX20028 General Description Features The MAX20028 evaluation kit (EV kit) is a fully assembled 3.5V to 36V Input Range and tested surface-mount PCB that contains all the 20A Quiescent Current with DC-DC Controller components necessary to evaluate the MAX20028 Enabled power-management IC (PMIC). The EV kit includes one Output Voltages high-voltage step-down controller and two low-voltage 5V Output at 5A (High-Voltage, Step-Down step-down converters. Controller, Buck 1) The EV kit can operate from 3.5V to 36V input voltages 3.3V Output at 3A (Step-Down Converter, Buck 2) and is optimized for automotive infotainment applications. 1.2V Output at 3A (Step-Down Converter, Buck 3) The high-voltage controller is configured for a 5V output High-Frequency Operation that provides at least 5A. The low-voltage step-down 2.1MHz or Optional Divide-Down Operation for converters are configured for 3.3V and 1.2V, each provid- Buck 1 ing up to 3A. The EV kit can be easily reconfigured to operate in continuous PWM mode, skip mode, or external Individual Enable Inputs and Reset Outputs synchronization operation. Proven PCB Layout The EV kit comes with MAX20028ATJA/VY+ device Fully Assembled and Tested installed, but is capable of evaluating other variants of the MAX20028 IC. Refer to the MAX20028 IC data sheet for external component selection. Ordering Information appears at end of data sheet. 319-100219A Rev 1 2/19MAX20028 Evaluation Kit Evaluates: MAX20028 420kHz. By default, Buck 1 is configured to operate at Quick Start 2.1MHz. To change the Buck 1 switching frequency to Recommended Equipment 420kHz, remove R22 and populate R21 with a 0 resistor. MAX20028 EV kit The switching frequencies of Buck 2 and Buck 3 are not affected by the CSEL1 input. For additional information, 3.5V to 36V, 4A DC power supply refer to the Buck 1 Clock Select (CSEL1) section in the Voltmeter MAX20028 IC data sheet. Procedure Low-Voltage Converters, Buck 2 and Buck 3 The EV kit is fully assembled and tested. Follow the steps Buck 2 and Buck 3 are low-voltage, synchronous step- below to verify board operation. Caution: Do not turn on down converters designed to operate directly from the the power supply until all connections are completed. Buck 1 output. Buck 2 is configured for a 3.3V output 1) Verify that a shunt is installed across pins 1-2 on and Buck 3 is configured for a 1.2V output. Both Buck 2 jumpers JU1JU3 and JU5JU7. and Buck 3 have a maximum output current of 3A. The output voltages are configurable between 0.8V and 3.6V 2) Verify that a shunt is installed across pins 2-3 on by resistor-dividers. Refer to the OUT2/OUT3 Adjustable jumper JU4. Output-Voltage Option section in the MAX20028 IC data 3) Connect the positive terminal of the power supply to sheet for additional information. the VBAT PCB pad. Connect the negative terminal of the power supply to the PGND PCB pads closest to Spread-Spectrum Operation (JU4) VBAT. The EV kit features a pin-selectable spread-spectrum 4) Set the power-supply VIN to 14V. mode of opera tion. Jumper JU4 enables or disables spread-spectrum operation (see Table 1). 5) Turn on the power supply and verify that the Buck 1 output (VOUT1) is 5V. Synchronization Input (JU5) 6) Verify that the Buck 2 output (VOUT2) is 3.3V. The EV kits SYNC input allows synchronization to an external clock. When synchronizing the device to an 7) Verify that the Buck 3 output (VOUT3) is 1.2V. external clock, leave jumper JU5 unconnected. For fixed- Detailed Description of Hardware frequency PWM mode operation, connect a shunt across pins 1-2 on JU5. For skip mode operation, connect a The MAX20028 EV kit comes fully assembled and shunt across pins 2-3 on JU5. tested with all the components necessary to evaluate the MAX20028 step-down controller with dual 2.1MHz Reset Outputs step-down DC-DC converters. The EV kit comes with The EV kit features individual RESET outputs for each a MAX20028ATJA/VY+ 32-pin side-wettable TQFN-EP buck that assert low when the buck output drops 6% device installed. However, other MAX20028 variants below the regulated voltage. RESET remains low for can be evaluated on the same EV kit with some simple a fixed timeout period of 3.9ms after the buck output modifications. Refer to the MAX20028 IC data sheet for rises up to its regulated voltage. RESET1 has a pullup additional information regarding component selection resistor, making it a logic-level output. RESET2 and when altering the EV kit. RESET3 are either logic-level or open-drain outputs, depending on jumpers JU6 and JU7 (see Table 1). High-Voltage Controller, Buck 1 Buck 1 is a high-voltage, step-down controller designed to Thermal Warning operate with a 3.5V to 36V input voltage range. Buck 1 is The EV kit features a thermal-warning indicator output. configured for a 5V output and up to 5A load current. To The ERR output asserts low when the junction tempera- change the Buck 1 output voltage to a fixed 3.3V, remove ture on the IC exceeds +145C (typ). The thermal-warning R7 and populat e R6 with a 0 resistor. indicator has a typical hysteresis of 15C. The Buck 1 switching frequency can be configured for 2.1MHz or the factory-trimmed divide-down frequency of Maxim Integrated 2 www.maximintegrated.com