Click here for production status of specific part numbers. Evaluates: MAX18066 MAX18066 Evaluation Kit MAX18166 General Description Quick Start The MAX18066 evaluation kit (EV kit) provides a proven Recommended Equipment design to evaluate the MAX18066 and MAX18166 high- MAX18066 EV kit efficiency, 4A, step-down regulators with integrated 12V, 4A DC power supply switches. The EV kit is preset with the MAX18066 for 1.8V output at load currents up to 4A from a 4.5V to 16V Load capable of 4A input supply. The MAX18166 is pin-compatible with the Digital voltmeter MAX18066 and can be ordered for evaluation with this EV kit. Procedure The EV kit is fully assembled and tested. Follow the steps Features below to verify board operation. 4.5V to 16V Input Voltage Range Caution: Do not turn on power supply until all Fixed 500kHz (MAX18066) and 350kHz (MAX18166) connections are completed. Switching Frequency 1) Connect the positive terminal of the 12V supply to the Adjustable Output Voltage Range from 0.606V to IN connector and the negative terminal to the nearest (0.9 x V ) GND connector. IN Proven PCB Layout 2) Connect the positive terminal of the 4A load to the VOUT connector and the negative terminal to the Fully Assembled and Tested nearest GND connector. Ordering Information appears at end of data sheet. 3) Connect the digital voltmeter across the VOUT connector and the nearest GND connector 4) Verify that a shunt is not installed on the EN jumper. 5) Turn on the DC power supply. 6) Enable the load. 7) Verify that the voltmeter displays 1.8V. 319-100500 Rev 0 2/20Evaluates: MAX18066 MAX18066 Evaluation Kit MAX18166 If a different output voltage is desired, revisit the feedback Detailed Description of Hardware resistor-divider (R5), the inductor, and output capacitor The MAX18066 EV kit evaluates the MAX18066 and calculations (refer to the Inductor Selection and Output- MAX18166 current-mode, synchronous, DC-DC buck Capacitor Selection sections in the MAX18066/MAX18166 converters. The EV kit is preset for MAX18066 for 1.8V IC data sheet). The compensation components (R7, C13, output and delivers an output current up to 4A with high C14, and C15) must be recalculated to ensure loop stability efficiency. The EV kit operates from an input voltage of (refer to the Compensation Design Guidelines section in 4.5V to 16V. The EV kit provides an adjustable output the MAX18066/MAX18166 IC data sheet). voltage from 0.606V to 90% of the input voltage through resistor-dividers R5 and R6. The EV kit features inde- Regulator Enable (EN) pendent device-enable control (EN) and power-good To shut down the converter, install a shunt on jumper EN. (PGOOD) signals that allow for flexible power sequencing. For normal operation, remove the shunt from EN. Soft-Start (SS) Power Good (PGOOD) The EV kit utilizes an adjustable soft-start function to limit PGOOD is an open-drain output that goes high impedance inrush current during startup. The soft-start time is adjusted when V exceeds 0.56V (typ). PGOOD is internally pulled FB by the value of C7, the external capacitor from SS to low when V falls below 0.545V (typ). PGOOD also FB GND. By default, C7 is currently 0.01F, which gives becomes low during shutdown. On the EV kit, the PGOOD a soft-start time of approximately 1.2ms. To adjust the test point is pulled up to V through resistor R8. Use the DD soft-start time, determine C7 using the following formula: GND PCB pad as a ground reference for this signal. C7 = (5A x t )/0.606V SS where t is the required soft-start time in seconds and SS C7 is in farads. Ordering Information Setting Output Voltage PART TYPE The EV kit can be adjusted from 0.606V to (0.9 x V ) by IN MAX18066EVKIT EV Kit changing the values of R5 and R6. To determine the value Denotes RoHS of the resistor-divider, first select R6 from 5k to 50k and then use the following equation to calculate R5: R5 = R6 x (V /V -1) OUT FB where the feedback threshold voltage V = 0.606V (typ). FB When regulating an output of 0.606V, short FB to OUT and keep R6 connected from FB to GND. Maxim Integrated 2 www.maximintegrated.com