19-4942; Rev 1; 5/10 MAX16839 Evaluation Kit The MAX16839 evaluation kit (EV kit) demonstrates three separate high-voltage, single-channel, linear highbrightness LED (HB LED) drivers using the MAX16839 IC. This EV kit is configured to supply an HB LED current of 100mA per channel and operates from a 5V to 40V rated power supply providing up to 300mA. The EV kit can withstand a 45V automotive load-dump condition. An input switch is included to evaluate pulse-widthmodulation (PWM) driving with supply chopping. The EV kit eases evaluation of the MAX16839 PWM dimming-control feature by providing three independent PWM inputs to all three channels. Each PWM input accepts a digital signal up to 10kHz. Additionally, multiple EV kits can be cascaded by using the MAX16839 FLTS signals. An input common-mode choke is also provided to facilitate EMI immunity testing. Features S Three Independent Channels for Driving High-Brightness LEDs S 100mA LED Current per Channel S Three Independent PWM Inputs S PWM Dimming Control Up to 10kHz S Operates from a 5V to 40V Supply S Supply Input Chopper Circuit S Capability for Cascading Multiple Kits S Proven PCB and Thermal Design S Fully Assembled and Tested Ordering Information PART TYPE MAX16839EVKIT+ EV Kit +Denotes lead(Pb)-free and RoHS compliant. Component List DESIGNATION QTY DESCRIPTION C1 1 1FF Q10%, 50V X7R ceramic capacitor (0805) Murata GRM21BR71H105K C2, C3, C4 3 0.022FF Q10%, 50V X7R ceramic capacitors (0805) Murata GRM216R71H223K C5, C6, C7 3 0.1FF Q10%, 50V X7R ceramic capacitors (0805) Murata GCM21BR71H104K 1 60V, 1A Schottky diode (SMA) Central Semi CMSH1-60M LEAD FREE (Top Mark: CS60M) D1 DESIGNATION QTY DESCRIPTION 1 60V 1.25A p-channel MOSFET (SOT23) Fairchild FDN5618P (Top Mark: 618) Q1 1 65V 100mA npn transistor (SOT23) Central Semi BC846A TR (Top Mark: 1A) or Fairchild BC846AMTF (Top Mark: 8AA) R1, R3, R5 3 4.12I Q1% resistors (0603) P1 R2, R4, R6 3 2.05I Q1% resistors (0603) R7, R9, R10 3 10kI Q5% resistors (1206) R8 1 2.2kI Q5% resistor (2010) U1, U2, U3 3 Programmable LED current regulators (6 TDFN-EP*) Maxim MAX16839ATT+ (Pkg. Code: T633+2) D2 1 15V Q 5%, 250mW zener diode (SOD523) Central Semi CMOZ15V LEAD FREE (Top Mark: H0) JU1, JU2, JU3 3 3-pin headers -- 11 Shunts (JU1-JU11) JU4-JU11 8 2-pin headers -- 1 L1 1 80V, 500mA common-mode choke TDK ZJYS81R5-2P24-G01 PCB: MAX16839 EVALUATION KIT+ *EP = Exposed pad. ________________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. Evaluates: MAX16839 General Description Evaluates: MAX16839 MAX16839 Evaluation Kit Component Suppliers SUPPLIER PHONE WEBSITE Central Semiconductor Corp. 631-435-1110 www.centralsemi.com Fairchild Semiconductor 888-522-5372 www.fairchildsemi.com Murata Electronics North America, Inc. 770-436-1300 www.murata-northamerica.com TDK Corp. 847-803-6100 www.component.tdk.com Note: Indicate that you are using the MAX16839 when contacting these component suppliers. Quick Start Required Equipment * 5V to 40V, 500mA adjustable DC power supply * Three series-connected HB LED strings rated no less than 100mA and a maximum forward voltage of 39V * See the LED Load Configuration section for more information Procedure The MAX16839 EV kit is fully assembled and tested. Follow these steps to verify board operation. Caution: Do not turn on the power supply until all connections are completed. 1) Verify that shunts are installed on pins 1-2 of jumpers JU1, JU2, and JU3 (100mA operation). 2) Verify that shunts are not installed on jumpers JU4-JU10 (independent operation). 3) Verify that a shunt is installed on jumper JU11 (bypass chopper circuit). 4) Set the power-supply output to 12V and disable the output. If the total forward voltage of the HB LED string is > 6.5V, ensure that the input supply rises in less than 14Fs, or connect the FLTS output to ground to disable the turn-off in case of fault feature. The IC can otherwise latch in fault condition at startup. 5) Connect the power-supply ground to the PGND PCB pad. 6) Connect the power-supply positive output to the VIN PCB pad. 7) Connect each HB LED string as follows: Channel 1: Connect an HB LED string anode to the LED1+ PCB pad and the cathode to the LED1PCB pad. Channel 2: Connect an HB LED string anode to the LED2+ PCB pad and the cathode to the LED2PCB pad. Channel 3: Connect an HB LED string anode to the LED3+ PCB pad and the cathode to the LED3PCB pad. 8) Enable the power-supply output. 9) Verify that the attached LEDs are illuminated. Detailed Description of Hardware The MAX16839 EV kit demonstrates three separate highvoltage, single-channel, linear HB LED drivers. Each linear current driver circuit uses a MAX16839 IC in a 6-pin TDFN surface-mount package with an exposed pad for enhanced thermal dissipation. On the EV kit, each driver circuit is configured to supply an HB LED current of 100mA per channel at 5% current accuracy. The MAX16839 ICs control the HB LED current by maintaining a 203mV (typ) drop across each channel's external sense resistors (R1 or R2 for channel 1, R3 or R4 for channel 2, and R5 or R6 for channel 3). Additionally, each channel can be reconfigured to provide down to 50mA of current. The EV kit operates from a 5V to 40V rated power supply providing up to 300mA and the EV kit can withstand a 45V load-dump condition. The input supply is filtered by common-mode choke L1 and capacitor C1, while battery-reverse protection is provided by diode D1. The input supply chopper circuit is comprised of p-channel MOSFET P1, biasing resistor/diode pair R7/ D2, and switching transistor Q1. See the Chopper-Circuit Operation section for more information on using the chopper circuit. The MAX16839 PWM dimming-control feature can be evaluated with an independent PWM input on each of the three channels. Each PWM input accepts a digital signal up to 10kHz at the DIM1, DIM2, or DIM3 and GND PCB pads. Additionally, each PWM input functions as an active-high enable for the corresponding channel. Multiple EV kits can be cascaded using the FLTS1, FLTS2, FLTS3, and GND PCB pads and configuring the proper jumpers. Jumpers JU8, JU9, and JU10 disable the MAX16839 fault-detection features. Each MAX16839 IC features an exposed pad that uses the top-layer and bottom-layer PCB copper as a heat-sink. For a single-layer design, the top-layer copper would only be required from a thermal-design perspective. The EV kit PCB uses 2oz copper for optimum thermal dissipation. 2 _______________________________________________________________________________________ MAX16839 Evaluation Kit HB LED Current Settings The EV kit features jumpers to reconfigure each MAX16839 linear current-sink circuit on each channel. When inserted on pins 1-2, jumpers JU1, JU2, and JU3 configure the current sink's limit to 100mA, respectively. Installing the jumpers on pins 2-3 configures the current sink's limit to 50mA. See Table 1 for channel 1, Table 2 for channel 2, and Table 3 for channel 3 jumper settings. To reconfigure the circuit for another current limit, replace resistor R2, R4, or R6 for channels 1, 2, and 3, respectively, and use the following equation to calculate a new value for the desired current: RSENSE = 203mV ILED _ If designing for a higher LED current, verify that the desired current setting does not exceed the power rating of the corresponding resistor (R1-R6) or the LED load. Do not set the LED current above 100mA. Faults (FLTS1, FLTS2, FLTS3) and Open HB LED Detection The EV kit features PCB pads for accessing the fault signal (FLTS_) at each IC (U1, U2, and U3). Storage capacitors C5, C6, and C7 are provided at each IC's FLTS pin, respectively, for fault retention/memorization. When the voltage across the capacitor exceeds 1.65V during a fault event, the respective HB LED driver turns off, unless this feature is disabled by connecting the FLTS output of the respective IC to ground. Jumpers JU6 and JU7 are provided to connect all FLTS signals together, which shuts down all channels if a fault is detected at one of them. See Table 4 for configuring the FLTS jumpers. Refer to the Open-LED Detection and Fault Event Status Memory section in the MAX16839 IC data sheet for further information on the FLTS signal. The MAX16839 integrated open HB LED detection feature is enabled when VIN > 7.38V (typ) and the voltage at the DIM pin is high and the IC thermal shutdown is low. When any of these conditions are violated, the faultdetection function is disabled. Dimming Operation where ILED_ is the desired HB LED current in amps ((ILED1, ILED2, and ILED3) and RSENSE is the new R2, R4, or R6 resistor value in ohms for obtaining the desired HB LED current. Install the respective jumper (JU1, JU2, or JU3) on pins 1-2 when configuring the channel for another current. The EV kit features three independent PWM PCB pads and jumpers for accessing/configuring the current-dimming input (DIM) signal at each IC (U1, U2, and U3). Jumpers JU4 and JU5 are provided to connect all the DIM signals together or to operate independently. Each channel can have a different dimming-signal pattern. Table 1. Channel 1 HB LED Current (JU1) Table 3. Channel 3 HB LED Current (JU3) SHUNT POSITION CS PIN HB LED CURRENT (mA) SHUNT POSITION CS PIN HB LED CURRENT (mA) 1-2* Connected to R2 100 1-2* Connected to R6 100 2-3 Connected to R1 50 2-3 Connected to R5 50 *Default position. *Default position. Table 2. Channel 2 HB LED Current (JU2) Table 4. Fault FLTS1, FLTS2, FLTS3 (JU6, JU7) SHUNT POSITION CS PIN HB LED CURRENT (mA) 1-2* Connected to R4 100 2-3 Connected to R3 50 *Default position. SHUNT POSITION U1, U2, AND U3 FLTS PINS FAULT OPERATION Installed Connected together Simultaneous Independent Independent Not installed* *Default position. _______________________________________________________________________________________ 3 Evaluates: MAX16839 LED Load Configuration The EV kit can drive three separate HB LED loads. Each load can consist of multiple HB LEDs in series with a total forward voltage up to 39V. If the HB LED forward voltage is > 6.5V, the input voltage must rise within 14Fs to avoid a fault, or the fault feature must be disabled by connecting the FLTS output to ground. The EV kit circuit drives HB LEDs rated for a minimum of 100mA and can be reconfigured to drive up to 50mA. Proper heat-sinking of the LEDs is important for optimum LED performance and durability. Evaluates: MAX16839 MAX16839 Evaluation Kit Use a digital PWM signal with a 5V logic level and a switching frequency between 100Hz and 10kHz. Frequencies lower than 100Hz can introduce flickering in the light output. Vary the duty cycle of the signal to adjust the LED brightness. LED brightness increases as the duty cycle increases and vice versa. When the PWM signal's duty cycle is 100%, the LEDs are continuously on. At 0% duty cycle, the outputs are disabled. See Table 5 for configuring the DIM_ jumpers. Refer to the PWM Dimming section in the MAX16839 IC data sheet for further information on the DIM signal. Additional Configurations and Features The EV kit includes several other features to facilitate evaluating the MAX16839 IC. A power-supply choppercircuit feature, and the ability to cascade multiple kits for operation, are detailed in the following sections. Chopper-Circuit Operation installed, jumper JU11 is provided to bypass the chopper circuit. To use the chopper circuit, connect a function generator with a digital signal to the CHOP and GND PCB pads. Use a 3V to 5V low-frequency pulse-width-modulated (PWM) signal to switch the chopper circuit on/off. Cascading Multiple Kits The EV kit features PCB pads and jumpers for cascading multiple kits. To cascade another EV kit, use the following guidelines: 1) Install all DIM_ shunts on jumpers JU4 and JU5. 2) Install all FLTS_ shunts on jumpers JU6 and JU7. 3) Connect the DIM3 PCB pad on kit #1 to the DIM1 PCB pad on kit #2. 4) Connect the FLTS3 pad on kit #1 to the FLTS1 pad on kit #2. The EV kit features a power-supply chopper circuit for the VIN input supply. The input supply chopper circuit is comprised of p-channel MOSFET P1, biasing resistor/ diode pair R7/D2, and switching transistor Q1. When 5) Connect the GND PCB pad nearest DIM3 on kit #1 to the GND PCB pad nearest the DIM3 pad on kit #2. Table 5. DIM1, DIM2, DIM3 (JU4, JU5) Table 6. Chopper-Circuit Operation (JU11) SHUNT POSITION U1, U2, AND U3 DIM PINS DIM OPERATION Installed Connected together Synchronous Not installed* Independent Independent *Default position. 6) Connect a common power supply to both kits' VIN and PGND PCB pads. SHUNT POSITION MOSFET P1/ BIASING RESISTOR R8 CHOPPERCIRCUIT OPERATION Installed Connected to ground Bypassed Not installed* Connected to Q1 Running *Default position. 4 _______________________________________________________________________________________ MAX16839 Evaluation Kit Evaluates: MAX16839 Figure 1. MAX16839 EV Kit Schematic _______________________________________________________________________________________ 5 Evaluates: MAX16839 MAX16839 Evaluation Kit 1.0" 1.0" Figure 2. MAX16839 EV Kit Component Placement Guide-- Component Side Figure 3. MAX16839 EV Kit PCB Layout--Component Side 6 _______________________________________________________________________________________ MAX16839 Evaluation Kit Evaluates: MAX16839 1.0" Figure 4. MAX16839 EV Kit PCB Layout--Solder Side _______________________________________________________________________________________ 7 MAX16839 Evaluation Kit Evaluates: MAX16839 Revision History REVISION NUMBER REVISION DATE 0 9/09 Initial release 1 5/10 Updated data sheet based on new revision of the IC DESCRIPTION PAGES CHANGED -- 2, 3 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 8 (c) Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc. Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: Maxim Integrated: MAX16839EVKIT+