Evaluates: MAX16832C/MAX16832A 19-4289 Rev 0 9/08 MAX16832C Evaluation Kit General Description Features The MAX16832C evaluation kit (EV kit) demonstrates the 6.5V to 65V Wide Supply Voltage Range MAX16832C hysteretic current-mode high-brightness 666mA HB LED Current LED (HB LED) driver IC. The MAX16832C EV kit is config- ured as a step-down topology with a constant-current HB Digital PWM Dimming Control LED driver circuit for external HB LEDs. The MAX16832C Analog Dimming Control EV kit operates from a DC supply voltage of 6.5V to 65V and is configured to deliver 666mA of current to user-sup- Thermal-Foldback and Temperature-Simulation plied HB LEDs. The output voltage for the HB LED string Circuit can go up to 64V and depends upon the EV kits input Demonstrates a Thermally Optimized PCB Layout voltage. Design The MAX16832C EV kit can be configured for digital pulse-width modulation (PWM) dimming operation Evaluates MAX16832A (IC Replacement Required) using a digital PWM input signal. The EV kit circuit also Lead-Free and RoHS Compliant features a thermal-foldback and temperature-simulation Fully Assembled and Tested circuit feature. The MAX16832C EV kit is a fully assem- bled and tested surface-mount board. Additionally, the Ordering Information PCB layout design has been maximized for optimum thermal dissipation. The MAX16832C EV kit can also PART TYPE evaluate a MAX16832A after replacing the IC, which can be ordered from the number listed below. MAX16832CEVKIT+ EV Kit Warning: Voltages exceeding 42V could exist on the +Denotes lead-free and RoHS compliant. LED+ and LED- output pads. Component List DESIGNATION QTY DESCRIPTION DESIGNATION QTY DESCRIPTION 0.300 1%, 0.5W sense resistor 1F 10%, 100V X7R ceramic capacitor (1210) R1 1 (1206) C1 1 Murata GRM32CR72A105K IRC LRC-LRF1206LF-01-R300-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) Not installed, ceramic capacitor TP1 1 PC mini red test point C3 0 (1210) TP2 1 PC mini black test point 100V, 2A Schottky rectifier (SMA) Step-down HB LED driver Central Semi CMSH2-100M D1 1 U1 1 (8 SO-EP*) (Top Mark: CS2100M) Maxim MAX16832CASA+ JU1, JU2 2 2-pin headers 2 Shunts (JU1, JU2) 220H, 1.28A inductor L1 1 1 PCB: MAX16832C Evaluation Kit+ Coilcraft MSS1260-224KLB *EP = Exposed pad. 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 MAX16832C when contacting these component suppliers. 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.MAX16832C Evaluation Kit Quick Start Detailed Description of Hardware The MAX16832C EV kit demonstrates the MAX16832C Required Equipment hysteretic constant-current HB LED driver in an 8-pin SO Before beginning, the following equipment is needed: package with an exposed pad. The MAX16832C EV kit is 6.5V to 65V, 1A power supply configured in a step-down topology with constant current driving a string of user-supplied external HB LEDs. The Two digital voltmeters MAX16832C EV kit operates from a DC supply voltage of A series-connected HB LED string rated no less 6.5V to 65V and requires up to 1A. The MAX16832C ICs than 666mA UVLO is configured from 6V to 6.5V internally. A current probe to measure HB LED current The EV kit circuit is configured to deliver 666mA of current into a series HB LED string with a maximum Procedures The MAX16832C EV kit is fully assembled and tested. 64V forward voltage. The average series inductor cur- rent is set to 666mA (typ) by resistor R1. The Follow the steps below to verify board operation. MAX16832C thermal-foldback feature can be evaluat- Caution: Do not turn on the power supply until all ed by connecting a negative temperature coefficient connections are completed. (NTC) thermistor between the TEMP I and PGND PCB Warning: Voltages exceeding 42V could exist on the pads on the EV kit. Alternatively, a temperature-vary- LED+ and LED- output pads. ing thermistor circuit can be simulated using poten- 1) Verify that a shunt is not installed across jumper tiometer R2 and resistor R3. The EV kit also features a JU1 (enabled). DIM PCB pad to evaluate digital PWM dimming opera- 2) Verify that a shunt is installed across jumper JU2 tion of the external HB LEDs. (temperature simulation). The MAX16832C EV kit uses a 1oz copper, 2-layer 3) Connect the power supplys positive terminal to the PCB. It has been designed to provide an example of VIN PCB pad on the EV kit. Connect the power sup- good thermal dissipation, incorporating thermal vias plys ground terminal to PGND PCB pad. under U1s exposed pad and additional thermal vias adjacent to U1. These vias carry additional heat to the 4) Connect digital voltmeters across the VIN and bottom-layer ground plane for maximum thermal con- PGND PCB pads and the LED+ and LED- PCB ductivity when evaluating a MAX16832 IC. pads. 5) Connect the anode of the HB LED string to the Jumper Selection LED+ pad. The MAX16832C EV kit features several jumpers to reconfigure the PWM dimming, thermal-foldback fea- 6) Connect the cathode of the HB LED string to the ture and for reconfiguring the external HB LED current. LED- pad. 7) Clip the current probe across the HB LED+ wire to Enable and HB LED Dimming Control measure the HB LED current. (Digital and Analog) The MAX16832C EV kit features a jumper to enable 8) Turn on the power supply and increase the power- and disable U1. Installing jumper JU1 disables the supply output voltage from 0V, slowly ramping it up MAX16832C IC. Additionally, HB LED dimming can be to 65V (HB LED dependant). Do not hot plug achieved on the MAX16832C EV kit by applying a digi- > 30V DC voltage on the evaluation board It will tal PWM signal at the DIM PCB input pad. The signal generate over 70V high-voltage spark on the can be applied using an open-collector or open-drain MAX16832C and damage the IC due to the power output rated for at least the VIN voltage. Alternatively, cable inductance-caused ringing with the input fil- resistor R4 can be removed and TTL logic can control ter capacitor. the DIM pin. Remove the shunt at jumper JU1 to enable 9) Using a voltmeter, verify that the voltage across HB LED dimming using a digital PWM signal at the DIM TP1 and TP2 is > 2V. If it is not, adjust potentiome- and PGND PCB pads. The applied signal should have ter R2 to obtain a reading > 2V. a 0.6V logic-low (or less) and a 2.8V logic-high (or greater) level and frequencies from 200Hz to 20kHz. To adjust the HB LED brightness, vary the signal duty cycle from 0% to 100%. See Table 1 for jumper JU1 setting of the HB LED dimming operation. 2 Evaluates: MAX16832C/MAX16832A