Evaluates: MAX16824 19-4045 Rev 0 2/08 MAX16824 Evaluation Kit General Description Features The MAX16824 evaluation kit (EV kit) demonstrates a Operates from a 6.5V to 28V, 0.5A Supply high-voltage, 3-channel, linear high-brightness LED 3 Channels for Driving High-Brightness LEDs (HB LED) driver using the MAX16824 IC. This EV kit is configured to supply an LED current of 100mA per 100mA LED Current per Channel channel and operates from a 0.5A, 6.5V to 28V rated Three Independent PWM Inputs power supply. PWM Dimming Control Up to 5kHz The EV kit eases evaluation of the MAX16824 pulse- width-modulation (PWM) dimming-control feature by Fully Assembled and Tested providing three independent PWM inputs to all three channels. Each PWM input accepts a digital signal up to 5kHz. Component List Ordering Information PART TYPE DESIGNATION QTY DESCRIPTION MAX16824EVKIT+ EV Kit 1F 10%, 50V X7R ceramic capacitor (1210) +Denotes lead-free and RoHS-compliant. C1 1 Murata GRM32RR71H105K or TDK C3325X7R1H105K Quick Start 1F 10%, 10V X5R ceramic Required Equipment C2 1 capacitor (0603) Before beginning, the following equipment is needed: Murata GRM188R61A105K MAX16824 EV Kit 2 1%, 0.25W sense resistors 6.5V to 28V, 0.5A adjustable DC power supply R1, R2, R3 3 (1206) Logic function generator IRC WCR-WCR1206LF-2R00-F Three LED loads, each rated as follows: Linear HB LED driver Current rating 100mA U1 1 (16-pin TSSOP-EP*) Total LED string forward voltage V 26.3V FLED Maxim MAX16824AUE+ See the LED Load Configuration section for more 1 PCB: MAX16824 Evaluation Kit+ information *EP = Exposed paddle. Procedure The MAX16824 EV kit is fully assembled and tested. Component Suppliers Follow the steps below to verify board operation. Caution: Do not turn on the power supply until all SUPPLIER PHONE WEBSITE connections are completed. IRC, Inc. 361-992-7900 www.irctt.com 1) Set the power-supply output to over V + 1.7V. FLED Murata Mfg. Co., 2) Set the function generator to produce a 5V-logic, 770-436-1300 www.murata.com Ltd 1kHz square wave with a 50% duty cycle. TDK Corp. 847-803-6100 www.component.tdk.com 3) Disable the power-supply and function generator Note: Indicate that you are using the MAX16824 when contact- output. ing these component suppliers. 4) Connect the power-supply ground to the GND pad next to the IN pad. 5) Connect the power-supply positive output to the IN pad. 6) Connect the logic function generator ground to the GND pad next to the PWM pads. Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com.MAX16824 Evaluation Kit 7) Connect the logic function generator output to each Output Current Setting of the PWM pads (PWM1, PWM2, and PWM3). The current for each MAX16824 EV kit LED channel (I , I , and I ) is configured to 100mA by LED1 LED2 LED3 8) Connect one LED load anode to each LED output three sense resistors (R1, R2, and R3, respectively). pad (LED1+, LED2+, or LED3+). See the equation below to select a different LED cur- 9) Connect each LED load cathode to the correspond- rent and a new resistor value. If designing for a higher ing LED input pad (LED1-, LED2-, or LED3-). LED current, verify that the desired current setting does 10) Enable the power-supply output. not exceed the power rating of the corresponding resis- tor (R1, R2, or R3) or the LED load. Do not set the LED 11) Enable the logic function generator signal output. current above 150mA. Use the following equation to 12) Verify that the attached LEDs are illuminated. calculate the value of the new resistor: Detailed Description of Hardware 200mV R = The MAX16824 EV kit demonstrates a high-voltage, I LED 3-channel, linear high-brightness LED driver using the MAX16824 IC in a 16-pin TSSOP surface-mount pack- where I is the desired LED current and R is the LED age. This EV kit is configured to supply an LED current resistor value required to set the desired current of the of 100mA per channel. The MAX16824 IC controls the LED channel. LED current by maintaining a 200mV drop across each external sense resistor (R1, R2, and R3). The EV kit High Input Voltage operates from a 0.5A, 6.5V to 28V rated power supply. and Thermal Protection The three independent PWM inputs (PWM1, PWM2, The MAX16824 IC operates in linear mode. As a result, and PWM3) control dimming for each channel. Each the IC can dissipate significant power if operated using a PWM input functions as an active-high enable for the high input voltage and a small V . High-power dissi- FLED corresponding LED channel. pation may cause the IC to go into thermal shutdown. Refer to the Thermal Protection section in the MAX16824/ The MAX16824 features an exposed paddle that uses MAX16825 IC data sheet for more information. the top-layer and bottom-layer PCB copper as a heatsink. The exposed paddle connects to GND. LED Dimming The MAX16824 EV kit features three independent PWM LED Load Configuration pads used for controlling LED brightness for each The MAX16824 EV kit can drive three separate LED channel. Each channel can have a different dimming loads. Each LED load can consist of multiple LEDs con- signal pattern. Use a digital PWM signal with a 5V logic nected in series. The LED loads forward voltage can level and a switching frequency between 100Hz and be up to 26.3V. The EV kit drives LEDs rated for at least 5kHz. Frequencies lower than 100Hz can introduce 100mA. Proper heat sinking of the LEDs is important for flickering in the light output. Vary the duty cycle of the optimum LED performance and durability. signal to adjust the LED brightness. LED brightness increases as the duty cycle increases and vice versa. When the PWM signals duty cycle is 100%, the LEDs are continuously on. At 0% duty cycle, the outputs are disabled. 2 Evaluates: MAX16824