Evaluates: MAX20037 MAX20037 Evaluation Kit General Description Benefits and Features The MAX20037 evaluation kit (EV kit) demonstrates the Configurable Charge-Detection Modes MAX20037 automotive high-current step-down DC-DC USB-IF BC1.2 CDP, DCP converter with USB protection/host charger adapter Apple 2.4A, 1.0A emulation. China YD/T1591-2009 Charging Specification The IC features integrated host-charger port- Automatic USB Voltage Adjustment by Integrated detection 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 MAX20037s 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 MAX20037 EV kit converter operates from a voltage up to 28V and is MINIQUSB command module and MAX20037 protected from load-dump transients up to 40V. The example GUI converter is programmable for frequencies from 275kHz Included 3m USB captive cable to 2.2MHz and can deliver 3A of continuous current at 105C. 2, 20W resistor or electronic load connected to a Type-A USB 2.0 connector (plug) 2 The EV kit is populated with an I C-enabled MAX20037. 2 The I C interface allows for flexible configuration, detailed 12V, 2A DC power supply or car battery (Supply A) fault diagnostics, and access to the on-chip ADC that 3.3V, 1A DC power supply (Supply B) 2 reports output voltage and current. The I C features are Two digital voltmeters (DVM1, DVM2) or easily accessed by using the Maxim command module one oscilloscope (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 EV kit comes with data-line tuning component pads popu- lated with short circuits. Tuning components are usu- Ordering Information appears at end of data sheet. ally not necessary for the low voltage, high-bandwidth data switches in MAX20037. Refer to Figure 17 in the MAX20037/MAX20038 IC data sheet for the MAX20037 untuned near-eye diagram. Samsung is a registered trademark of Samsung Electronics Apple, iPod, iPhone, and iPad are registered trademarks of Apple Inc. Co., Ltd. 319-100140 Rev 0 2/18Evaluates: MAX20037 MAX20037 Evaluation Kit 9) Connect the load to the end of the USB cable. Procedure The EV kit is fully assembled and tested. Follow the steps 10) With the voltage adjustment disabled (GAIN = 0x0 below to verify board operation: default setting), measure the voltage: a) The voltage at the buck output (USB 5V) should 1) Connect Supply A (turned off) between the VBAT still be approximately 5V. There is a slight drop and GND test points. due to load regulation and the current through 2) Connect Supply B (turned off) between the 3V3 the current-sense resistor, output filter, and PCB header and GND test point. trace. 3) Connect the USB cable, but leave the load b) The voltage at the far end of the USB cable disconnected. will be noticeably below 5V. The voltage drop 4) Connect DVM1 (or oscilloscope channel 1) between is caused by the load current flowing through the the USB 5V and GND test points on the EV kit (this cable resistance. is the output of the buck). 11) Using the GAIN drop-down list in the GUI, set the gain 5) Connect DVM2 (or oscilloscope channel 2) to VBUS to 661m, which is the maximum setting. and GND at the far-end of the USB cable (this is the 12) The voltage at the buck output should increase to voltage a portable device sees). 6.8V, and the voltage at the end of the USB cable should now be approximately 5V. 6) Power on Supply A at 12V with a 2A current limit and 13) The far-end voltage can be fine-tuned by adjusting the Supply B at 3.3V with a 0.2A current limit. GAIN register to match the specific cable. Once the 7) Both DVM1 and DVM2 should measure approxi- GAIN register is adjusted correctly, the far-end volt- mately 5V. age should maintain 5V regardless of load current. 2 8) Establish I C communication with the GUI: a) Visit