Evaluates: MAX20038 MAX20038 Evaluation Kit General Description Benefits and Features The MAX20038 evaluation kit (EV kit) demonstrates the Configurable Charge-Detection Modes MAX20038 automotive high-current, high-efficiency step- USB-IF BC1.2 CDP, DCP down DC-DC converter with integrated USB protection Apple 2.4A, 1.0A and host charger adapter emulation. China YD/T1591-2009 Charging Specification The IC features integrated host-charger port-detec- Automatic USB Voltage Adjustment by Integrated tion circuitry adhering to the USB-IF BC1.2 battery DC-DC Converter (275kHz to 2.2MHz) charging specification, Apple iPod /iPhone /iPad Proven PCB Layout and Samsung charge-detection termination resistors, Fully Assembled and Tested and Chinese Telecommunication Industry Standard YD/T 1591-2009. Quick Start The IC integrates high side current-sensing and voltage- The following procedure demonstrates the MAX20038s adjustment circuitry that provides automatic USB voltage 2 voltage-adjustment capability and I C interface. adjustment to compensate for voltage drops in captive cables associated with automotive applications. Required Equipment The high-efficiency, step-down, synchronous, DC-DC MAX20038 EV kit converter operates from a voltage up to 28V and is MINIQUSB EV kit and MAX20038 example GUI protected from load dump transients up to 40V. The Included 3m USB captive cable converter is programmable for frequencies from 275kHz 2, 20W resistor or electronic load connected to a to 2.2MHz and can deliver 3A of continuous current at Type-A USB 2.0 connector (plug) 105C. 2 The EV kit is populated with an I C-enabled MAX20038. 12V, 2A DC power supply or car battery (Supply A) 2 The I C interface allows for flexible configuration, detailed 3.3V, 1A DC power supply (Supply B) fault diagnostics, and access to the on-chip ADC that Two digital voltmeters (DVM1, DVM2) or 2 reports output voltage and current. The I C features are one oscilloscope easily accessed by using the Maxim command module (MINIQUSB) along with the provided example GUI. The EV kit is configured for 2.2MHz operation, and the included 3m USB cable allows for demonstration of the cable compensation capability of the IC. The high-voltage data switches of the MAX20038 require data line tuning to achieve an optimal eye diagram. The EV kit comes populat- Ordering Information appears at end of data sheet. ed with tuning components optimized for use with the sup- plied cable. Refer to Figure 19 in the MAX20037/MAX20038 IC data sheet for the MAX20038 tuned near-eye diagram. Apple, iPod, iPhone, and iPad are registered trademarks of Apple Inc. Samsung is a registered trademark of Samsung Electronics Co., Ltd.. 319-100154 Rev 0 3/18Evaluates: MAX20038 MAX20038 Evaluation Kit 12) The voltage at the buck output should increase to Procedure 6.8V, and the voltage at the end of the USB cable The EV kit is fully assembled and tested. Follow the steps should now be approximately 5V. below to verify board operation: 13) The far-end voltage can be fine-tuned by adjusting the 1) Connect Supply A (turned off) between the VBAT GAIN register to match the specific cable. Once the and GND test points. GAIN register is adjusted correctly, the far-end volt- 2) Connect Supply B (turned off) between the 3V3 age should maintain 5V regardless of load current. header and GND test point. Optional: Using the On-Chip ADC 3) Connect USB cable, but leave the load disconnected. 14) Ensure that the Read V/I ADC and Auto Read 4) Connect DVM1 (or oscilloscope channel 1) between checkboxes are checked. the USB 5V and GND test points on the EV kit (this 15) Click on the Int ADC V/I Done checkbox. USB V is the output of the buck). and USB I will update with the voltage on SENSP 5) Connect DVM2 (or oscilloscope channel 2) to VBUS and the voltage across R respectively. SENSE and GND at the far-end of the USB cable (this is the a. The ADC values updates once for every write of Int voltage a portable device sees). ADC V/I Done. 6) Power on Supply A at 12V with a 2A current limit and Detailed Description Supply B at 3.3V with a 0.2A current limit. The MAX20038 EV kit comes fully assembled, tested, 7) Both DVM1 and DVM2 should measure approxi- and installed with a MAX20038ATIA/V+ IC. Stand-alone mately 5V. variants can be used on this EV kit by changing the IC 2 8) Establish I C communication with the GUI: and configuration resistors. a) Visit