Evaluates: MAX16802B 19-0560 Rev 0 5/06 MAX16802B Evaluation Kit General Description Features The MAX16802B evaluation kit (EV kit) demonstrates a 10.8V to 30V Wide Supply Voltage Range current-controlled, high-output-current LED driver Current-Controlled Output based on the MAX16802B. This EV kit is capable of supplying stable output currents of up to 750mA, can Up to 750mA LED Current at 12V Output run at supply voltages between 10.8V and 30V, and can Linear and PWM Dimming Control operate at temperatures ranging from -40C to +85C. The MAX16802B EV kit features two different types of Over 80% Efficiency at Full Load dimming controls using either a linear input voltage or a Supply Undervoltage Lockout PWM input signal to control the LED brightness. This EV kit also has a UVLO feature to turn off the EV kit opera- Output Overvoltage Protection tion during low input supply voltage and an overvoltage protection to protect the EV kit under an open-LED con- dition. The MAX16802B EV kit is a fully assembled and Ordering Information tested board. Warning: Under severe fault or failure conditions, this PART TEMP RANGE IC PACKAGE EV kit may dissipate large amounts of power, which MAX16802BEVKIT -40C to +85C 8 MAX could result in the mechanical ejection of a component or of component debris at high velocity. Operate this EV kit with care to avoid possible personal injury. MAX is a registered trademark of Maxim Integrated Products, Inc. Component List DESIGNATION QTY DESCRIPTION DESIGNATION QTY DESCRIPTION 4.7H, 4.2A peak SMD inductor 4.7F, 50V X7R ceramic capacitors L1 1 C1, C2, C5, C6 4 Coilcraft DO3308P-472ML Murata GRM32ER71H475KA88L 60V, 3.2A n-channel MOSFET Q1 1 0.1F, 50V X7R SMD ceramic Vishay Si3458DV capacitors C3, C4, C7 3 R1 1 392k 1%, 1/8W resistor (0603) Murata GRM188R71H104KA93D or R2 1 11k 1%, 1/8W resistor (0603) TDK C1608X7R1H104K R3 1 499k 1%, 1/8W resistor (0603) 470pF, 50V X7R ceramic capacitor C8 1 Murata GRM188R71H471KA01D or R4 1 73.2k 1%, 1/8W resistor (0603) TDK C1608X7R1H471K R5, R7 2 1k 1%, 1/8W resistors (0603) 1nF, 50V X7R ceramic capacitor R6 1 330 1%, 1/4W resistor (1206) C9 1 Murata GRM188R71H102KA01D or R8 1 220 1%, 1/8W resistor (0603) TDK C1608X7R1H102K 0.10 1%, 1/2W resistor (1206) 22V, 1.5W zener diode R9 1 D1 1 Susumu RL1632R-R100-F Vishay SMZG3797B R10 1 1 5%, 1/8W resistor (0603) 60V, 1A Schottky diode D2 1 Central Semiconductor CMSH1-60M U1 1 MAX16802B (8-pin MAX) or Diodes Inc. B160 VIN, VLED, 0.1in, 2-pin male connectors 20V, small-signal Schottky diode PWM IN, 4 (through hole) D3 1 Vishay SD103CWS or LIN IN Diodes Inc. SD103CWS 1 MAX16802B PC board 0.1in, 2-pin hole headers J1, J2 2 (through hole) Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com.MAX16802B Evaluation Kit This EV kit is based on a discontinuous current mode Quick Start (DCM) buck-boost converter operating at 262kHz to The MAX16802B EV kit is fully assembled and tested. deliver a finite amount of energy to the output every Follow these steps to verify operation. Do not turn on cycle. The amount of this energy depends primarily on the power supply until all connections are completed. the value of the inductor and the user-programmable 1) Connect a DC power supply (0 to 30V or above, 1A) peak inductor current and does not depend on the sup- to +VIN and GND. ply voltage. Due to this configuration, the power output of the EV kit, and thus the output current supplied to the 2) Connect a voltmeter or oscilloscope and the LED LED at a given LED operating voltage, becomes inde- array (connected in series to drop about 12V at pendent of the supply voltage. 750mA forward current) to +VLED and -VLED with anode connected to +VLED and cathode to -VLED. This EV kit is designed to drive LED loads capable of taking up to 750mA of maximum current at a 12V operat- 3) Close the jumpers J1 and J2 to disable dimming. ing voltage. If an LED load with lower operating voltage 4) Turn on the power supply and increase the input is used, then the maximum output current will increase voltage to above 10.8V. The output voltage increas- by the same ratio to maintain the output power constant. es to forward bias the LED array and delivers To drive an LED array with a different operating voltage, approximately 750mA regulated average LED cur- the value of the current-sense resistor needs to be rent. Increase the supply further up to 30V and the adjusted. Calculation of the current-sense resistor for a output average current will be regulated throughout different output operating voltage is explained in later the range. sections. 5) Open shunt J1 and apply a PWM signal to PWM IN Input Supply UVLO with a frequency of 200Hz and 0 to 2V amplitude. Input supply UVLO is implemented by using a resistor Vary the duty cycle from 0 to 100% and the LED network that combines R3 and R4, which senses the brightness varies from 100% to 0%. When the PWM input supply voltage and uses the EN pin to turn on the duty cycle is 0%, the LED brightness is 100%. circuit when the input supply voltage goes above 6) Close J1, and then open J2. Connect a variable volt- 10.8V. The wake-up threshold of EN is 1.23V when the age source to LIN IN and vary the voltage between voltage at EN is rising, and it has a hysteresis of 50mV. 0 and 1.6V. The LED brightness varies from 100% to Once the device is turned on, due to the hysteresis, the 0%. When the voltage input at LIN IN is 0V, the LED device turns off only if the input supply voltage goes brightness is 100%. below 10.4V. Caution: Avoid powering up the EV kit without con- The UVLO threshold can be adjusted by varying R1 or necting load. R2 using the equation below: Detailed Description V UVLO R3=14R The MAX16802B evaluation kit is a current-controlled, 12. 3 high-output-current LED driver capable of supplying where V is the desired UVLO threshold. To main- UVLO constant currents up to 750mA, irrespective of supply tain threshold accuracy, keep the value of R4 less than voltage variations. 100k . Component Suppliers SUPPLIER PHONE FAX WEBSITE Central Semiconductor 631-435-1110 631-435-3388 www.centralsemi.com Coilcraft 847-639-6400 847-639-1469 www.coilcraft.com Diodes Inc. 805-446-4800 805-446-4850 www.diodes.com Murata 770-436-1300 770-436-3030 www.murata.com Susumu Co Ltd. 208-328-0307 208-328-0308 www.susumu-usa.com TDK 847-390-4373 847-390-4428 www.component.tdk.com Vishay 402-563-6866 402-563-6296 www.vishay.com Note: Indicate you are using the MAX16802B when contacting these manufacturers. 2 Evaluates: MAX16802B