Evaluates: MAX20051/MAX20053 MAX20051 Evaluation Kit General Description Features and Benefits The MAX20051 evaluation kit (EV kit) demonstrates the 4.5V to 65V Input Voltage MAX20051 and MAX20053, 2A synchronous buck LED Drives 1 to 16 LEDs drivers with integrated MOSFETs. 0A to 2A LED Current The EV kit operates from a DC supply voltage from Demonstrates Undervoltage-Lockout and Output- 4.5V to 65V and the switching frequency is fixed at Short Protection 400kHz. Spread-spectrum mode (SSM) is enabled for Demonstrates Current-Limit and Thermal-Shutdown EMI improvement. The EV kit demonstrates both analog and pulse-width modulation (PWM) dimming. The EV kit Feature also demonstrates short LED, open LED, and overtem- Demonstrates 5V, 10mA LDO Output Capability perature-fault protection. Proven PCB Layout and Thermal Design The EV kit also comes with a MAX20053 IC, which can Fully Assembled and Tested be installed to evaluate the 2.1MHz switching frequency device. Refer to the Evaluating the MAX20053 section for Ordering Information appears at end of data sheet. more information. MAX20051 EV Kit Photo 19-7363 Rev 0 10/14Evaluates: MAX20051/MAX20053 MAX20051 Evaluation Kit frequency average current-mode step-down LED driver. Quick Start The device uses high-side current regulation, meaning Required Equipment a current-sense resistor is placed on the high side of the MAX20051 EV kit LED string, and the voltage across the current-sense resistor is sensed and used to regulate the LED current. 5V to 65V, 4A DC power supply The device offers both analog and PWM dimming. Two digital voltmeters (DVMs) Analog Dimming One series-connected HB LED string rated to no less than 2.5A The EV kit demonstrates the analog dimming feature of the device. R6 and R7 form a resistor-divider between Current probe to measure the HB LED current VCC and AGND. R6 is a 10k resistor and R7 is a 10k Small flat-blade screwdriver to turn the potentiometer potentiometer, with the wiper shorted to the high side of wiper-adjustment pin the potentiometer. Using a flat-blade screwdriver, turn the wiper-adjustment pin clockwise to increase the voltage on Procedure the REFI input. Turn the wiper-adjustment pin counter- The EV kit is fully assembled and tested. Follow the steps clockwise to decrease the voltage on the REFI input. below to verify board operation: The REFI input allows for analog dimming of the HB LED 1) Connect the HB LED string anode to the LED+ PCB string. A REFI input voltage of 0.2V or less turns off the pad and the cathode to the PGND PCB pad. LED driver. A REFI input voltage between 0.2V and 1.2V 2) Connect the first DVM across the LED+ and PGND provides linear dimming of the HB LED string. A REFI input PCB pads. voltage greater than 1.2V sets the HB LED string current 3) Connect the second DVM across the REFI test point to maximum current (based on the current-sense resistor). and AGND test point. Alternatively, the analog dimming input can be set with 4) Connect the power supply to the VIN PCB pad and a power supply. Remove R12 and connect the power the power supplys ground to the PGND PCB pad. supply directly to the REFI test point to perform analog 5) Clip the current probe across the wire connecting the dimming with a power supply. Be careful not to violate HB LED string to the EV kit. the absolute maximum voltage rating of V + 0.3V CC 6) Turn on the power supply and set it to a voltage great- (refer to the Absolute Maximum Ratings section in the er than the maximum HB LED string voltage, but less MAX20050MAX20053 IC data sheet). than the 65V maximum input voltage. 7) Use the screwdriver to turn the potentiometer until the PWM Dimming second DVM reads 1.2V. The EV kit demonstrates the PWM dimming feature of 8) Measure the HB LED current using the current probe the device. Connect a PWM signal to the PWM test point. and verify that the current is 2A. Vary the duty cycle to increase or decrease the intensity 9) Verify that the first DVM shows the expected LED of the HB LED string. The PWM input of the device has 2V string voltage. (max) rising threshold and a 0.8V (min) falling threshold 10) Use the screwdriver to turn the potentiometer until the so it is compatible with 3.3V and 5V logic-level signals. second DVM reads 0.7V. The PWM input is pulled up to V through an external CC 11) Measure the HB LED current using the current probe 10k resistor on the EV kit. and verify that the current is 1A. Fault Indicator Detailed Description of Hardware The EV kit demonstrates the fault-protection features of The MAX20051 EV kit demonstrates the MAX20051 2A the device. The device offers shorted LED, open LED, synchronous buck LED driver with integrated MOSFETs. and overtemperature protection. The FLT output is an The device consists of a fully synchronous step-down open-drain, active-low fault indicator. Refer to the Fault converter with integrated MOSFETs and is capable of Pin Behavior section in the MAX20050MAX20053 IC driving a series string of LEDs at up to 2A, with a minimum data sheet for more information. number of external components. The device is a fixed- Maxim Integrated 2 www.maximintegrated.com