Click here to ask an associate for production status of specific part numbers. Evaluates: MAX20446C MAX20446C Evaluation Kit General Description Quick Start The MAX20446C evaluation kit (EV kit) demonstrates the Required Equipment MAX20446C, an integrated 6-channel high-brightness MAX20446C EV kit LED driver with boost controller for automotive displays. 5V to 36V, 4A DC power supply The EV kit operates from a DC supply voltage between Two digital voltmeters (DVMs) 4.5V and 36V, and the switching frequency can be either set at 2.2MHz or at 400kHz. The EV kit operates in Six series-connected HB LED strings (6 LEDs each) stand-alone mode. Spread-spectrum mode is enabled by rated to no less than 120mA default for EMI improvement. The EV kit demonstrates Current probe to measure the HB LED current phase-shifted pulse-width modulation (PWM) dimming. Dimming can be performed externally using a PWM Procedure signal applied to the DIM PCB pad. The hybrid dimming The EV kit is fully assembled and tested. Follow these feature can also be enabled through a resistor connected steps to verify board operation. between the SET pin and GND to reduce EMI. The EV Caution: Do not turn on the power supply until all kit also demonstrates short-LED, open-LED, boost output connections are completed. undervoltage and overvoltage, and overtemperature-fault 1) Verify that Jumper J17 is closed and that Jumper J22 protection. is open (2.2MHz switching frequency selected). For operation at switching frequencies other than 2.2MHz 2) Verify that Jumper J1 is closed (DS1 green LED or 400kHz, the external components should be chosen connected). according to the calculations in the MAX20446C IC data sheet. 3) Verify that Jumper J20 is closed (FAULT signaling enabled through DS2 red LED). Features 4) Verify that a shunt is installed across pins 1-2 on Demonstrates Robustness of MAX20446C Jumper J2 (device enabled). Wide 4.5V to 36V Input Operating Range (Up to 52V 5) Verify that Jumpers JMP1JMP3, JMP6-JMP7, and Load Dump) JMP9 have shunts installed across pins 1-2 (bleed resistors connected, all current sinks enabled). Powers HB LEDs (up to six strings) for Medium-to- Large-Sized LCD Displays in Automotive and Display 6) Verify that a shunt is installed across pins 2-3 on Backlight Applications Jumper J29 (LED short detection threshold set to 8V). 400kHz to 2.2MHz Resistor-Programmable Switching 7) Verify that a shunt is installed across pins 2-3 on Frequency with Spread-Spectrum Option Jumper J30 (LED current range set to 85mA120mA and hybrid dimming function disabled). Phase-Shift Dimming 8) Verify that Jumper J8 is closed (LED current set to Demonstrates Cycle-by-Cycle Current Limit and 100mA). Thermal-Shutdown Features 9) Connect the positive terminal of the power supply to Demonstrates Wide Dimming Ratio the IN PCB pad. Connect the negative terminal of Proven PCB and Thermal Design the power supply to a PGND PCB pad. Fully Assembled and Tested 10) Connect a DVM across OUT1 and GND PCB pads. Ordering Information appears at end of data sheet. 319-100695 Rev 0 2/21 2021 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. One Analog Way, Wilmington, MA 01887 U.S.A. Tel: 781.329.4700 2021 Analog Devices, Inc. All rights reserved.MAX20446C Evaluation Kit Evaluates: MAX20446C 11) Connect the six LED strings from V to the OUT1, between SET and GND or SET connected to V OUT CC OUT2, OUT3, OUT4, OUT5, and OUT6 PCB pads. Higher: 85-120mA) and by setting the LED strings current in steps of 5mA through a resistor connected between 12) Clip the current probe across the channel 1 HB ISET pin and GND. LED+ wire to measure the LED current. Jumpers JMP1JMP3, JMP6JMP7, and JMP9 can be 13) Turn on the power supply and set it to 12V. The used to disable outputs selectively when the HB LED green LED (DS1) and the LED strings should be on string is not connected. at this point. The EV kit features PCB pads to facilitate connecting HB 14) Measure the voltage from each of the OUT PCB LED strings for evaluation. The V PCB pads provide pads to PGND and verify the lowest voltage is OUT connections for connecting each HB LED strings anode to approximately 1V. the DC-DC pre-regulator output. The OUT1OUT6 PCB 15) Measure the LED current using the current probe pads provide connections for connecting each HB LED and verify all channels. strings cathode to the respective current sink. Capacitors C11, C14, C18, C23, C24, and C25 are included on the Detailed Description of Hardware design to prevent oscillations and provide stability when The MAX20446C EV kit demonstrates the MAX20446C using long, untwisted HB LED connecting cables during HB LED driver with an integrated step-up DC-DC pre- lab evaluation. These capacitors are not required if the regulator followed by six linear current sinks to drive up to connection between the LED driver and the HB LEDs is six strings of LEDs. The pre-regulator switches at 2.2MHz low-inductance. (or at 400kHz) and operates as a current-mode controlled A DIM PCB pad is provided for using a digital PWM signal regulator, providing up to 720mA for the linear current to control the brightness of the HB LEDs. Test points are sinks as well as overvoltage protection. The cycle-by- also provided for easy access to the devices V regu- CC cycle current limit is set by resistor R27, while resistors lator output as well as the COMP pin and the switching R4 and R5 set the over-voltage protection level to 29V. node of the pre-regulator (LX). The preregulator power section consists of inductor L2, power-sense resistor R27, Q4 MOSFET, and switching Power LED Enable (J1) diode D1. The EV kit circuit operates from a 4.5V DC sup- A green LED (DS1) is used to indicate that the EV kit ply voltage up to the HB LED forward string voltage. The is powered on. The LED can be disconnected from circuit handles load-dump conditions up to 50V. the power supply, allowing precise current-consumption The EV kit circuit demonstrates ultra-low shutdown cur- evaluation. See Table 1 for shunt positions. rent when the EN pin of the device is pulled to GND by shorting the EN PCB pad to GND. Each of the six linear Table 1. DS1 Enable (J1) current sinks (OUT1OUT6) is capable of operating up to 48V, sinking up to 120mA per channel. SHUNT POSITION DS1 POWER LED Closed* Connected The six channels linear current sinks are configured by selecting the current range through the SET pin (resistor Open Disconnected values from 3.48k to 27.4k between SET and GND *Default position. Lower: 45mA-80mA/resistor values from 36.5k to 75k Analog Devices 2 www.analog.com