Evaluates: MAX16822B/MAX16822A 19-4211 Rev 0 7/08 MAX16822B Evaluation Kit General Description Features The MAX16822B evaluation kit (EV kit) demonstrates 6V to 65V Wide Supply Voltage Range the MAX16822B hysteretic current-mode high-bright- 333mA LED Current ness LED (HBLED) driver IC. The MAX16822B EV kit is configured as a step-down topology with a constant- Digital PWM Dimming Control current HBLED driver circuit for external HBLEDs. The Analog Dimming Control MAX16822B EV kit operates from a DC supply voltage of 6V to 65V and is configured to deliver up to 350mA Thermal Foldback and Temperature Simulation of current to user-supplied HBLEDs. The output voltage Circuit for the HBLED string can go up to 64V and depends Evaluates MAX16822A (IC Replacement Required) upon the EV kits input voltage. Fully Assembled and Tested The MAX16822B EV kit can be configured for digital pulse-width modulation (PWM) dimming operation using a digital PWM input signal to control the HBLEDs Ordering Information brightness. The MAX16822B has an undervoltage lock- out (UVLO) feature that disables the EV kit at low input PART TYPE voltage. The EV kit circuit also features a thermal fold- back and temperature simulation circuit feature. The MAX16822BEVKIT+ EV Kit MAX16822B EV kit is a fully assembled and tested sur- +Denotes lead-free and RoHS compliant. face-mount board. The MAX16822B EV kit can also evaluate the MAX16822A, or for higher currents, a MAX16832 IC. Warning: Voltages exceeding 42V may exist on the LED+ and LED- output pads. Component List DESIGNATION QTY DESCRIPTION DESIGNATION QTY DESCRIPTION 1F 10%, 100V X7R ceramic 0.600 1%, 0.5W sense resistor C1 1 capacitor (1210) R1 1 (1206) Murata GRM32CR72A105K IRC LRC-LRF1206LF-01-R600-F 0.01F 10%, 50V X7R ceramic R2 1 100k 10% potentiometer C2 1 capacitor (0603) R3 1 20k 5% resistor (0805) Murata GRM188R71H103K R4 1 100k 5% resistor (0805) C3 0 Not ins tal l ed, cer am i c cap acito r ( 1210) TP1 1 PC mini red test point 100V, 1A Schottky rectifier diode TP2 1 PC mini black test point (SMB) D1 1 Step-down HBLED driver (8 SO) Central Semiconductor CMSH1-100 U1 1 Maxim MAX16822BASA+ (Top Mark: CS100) 2 Shunts (JU1, JU2) JU1, JU2 2 2-pin headers 1 PCB: MAX16822B Evaluation Kit+ 220H, 0.720A inductor L1 1 Coilcraft MSS1038-224KL 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.MAX16822B Evaluation Kit Component Suppliers SUPPLIER PHONE WEBSITE Central Semiconductor Corp. 631-435-1110 www.centralsemi.com Coilcraft, Inc. 847-639-6400 www.coilcraft.com IRC, Inc. 361-992-7900 www.irctt.com Murata Electronics North America, Inc. 770-436-1300 www.murata-northamerica.com Note: Indicate that you are using the MAX16822B when contacting these component suppliers. 8) Turn on the power supply and increase the input Quick Start voltage to 48V (HBLED dependent). Required Equipment 9) Using a voltmeter, verify that the voltage across TP1 Before beginning, the following equipment is needed: and TP2 is > 2V. If it is not, adjust potentiometer R2 MAX16822B EV kit to obtain a reading > 2V. 6V to 65V, 500mA power supply Detailed Description of Hardware Two digital voltmeters The MAX16822B evaluation kit (EV kit) demonstrates the MAX16822B hysteretic constant-current HBLED dri- A series-connected HBLED string rated no more ver in an 8-pin SO package. The MAX16822B EV kit is than 350mA configured in a step-down topology with constant cur- A current probe to measure HBLED current rent, driving a string of user-supplied external HBLEDs. The MAX16822B EV kit operates from a DC supply volt- Procedure age of 6V to 65V and requires up to 500mA. The The MAX16822B EV kit is fully assembled and tested. MAX16822B ICs UVLO is configured from 6V to 6.5V Follow the steps below to verify board operation. internally. Caution: Do not turn on the power supply until all connections are completed. The EV kit circuit is configured to deliver 350mA of cur- rent into a series HBLED string with a maximum 64V Warning: Voltages exceeding 42V may exist on the forward voltage. The average series inductor current is LED+ and LED- output pads. set to 333mA (typ) by resistor R1. The MAX16822B 1) Verify that a shunt is not installed across jumper thermal foldback feature can be evaluated by connect- JU1 (enabled). ing a negative temperature coefficient (NTC) thermistor 2) Verify that a shunt is installed across jumper JU2 to the TEMP I and PGND PCB pads on the EV kit. (temperature simulation). Alternatively, a temperature-varying thermistor circuit can be simulated using potentiometer R2 and resistor 3) Connect the power supplys positive terminal to the R3. The EV kit also features a DIM PCB pad to evaluate VIN PCB pad on the EV kit. Connect the power sup- digital PWM dimming operation of the external HBLEDs. plys ground terminal to PGND PCB pad. The MAX16822B EV kit PCB has been designed for 4) Connect the digital voltmeters across the VIN and maximum thermal dissipation when evaluating the PGND PCB pads and the LED+ and LED- PCB MAX16832 IC. The PCB has thermal vias under U1 and pads. additional thermal vias adjacent to U1s copper pad. 5) Connect the anode of the HBLED string to the LED+ These vias carry additional heat to the bottom layer pad. ground plane for maximum thermal conductivity. 6) Connect the cathode of the HBLED string to the However, these vias are not a PCB layout requirement LED- pad. for the MAX16822 design. 7) Clip the current probe across the HBLED+ wire to Jumper Selection measure the HBLED current. The MAX16822B EV kit features several jumpers to reconfigure the PWM and linear dimming, thermal foldback feature, and for reconfiguring the external HBLED current. 2 Evaluates: MAX16822B/MAX16822A