19-0842; Rev 0; 6/07 MAX16818 Evaluation Kit The MAX16818 evaluation kit (EV kit) is a fully assembled and tested surface-mount printed-circuit board (PCB) designed to evaluate the MAX16818 pulse-width modulation (PWM) LED driver controller in a buck-boost configuration. The MAX16818 EV kit operates from a DC supply voltage of 6V to 28V. The EV kit's output is configured to deliver at least 1A of current into an 18V series LED string. The LED brightness can be dimmed using a digital PWM signal. The EV kit provides an option to configure the MAX16818 IC's overvoltage protection, switching frequency, and frequency compensation. The MAX16818 EV kit also features a 180 out-of-phase clock output PCB pad. Features 6V to 28V Input-Voltage Range 1A Output Current into an 18V LED String Pulse-Width Modulated LED Current Dimming Resistor-Adjustable Overvoltage Protection and Switching Frequency 180 Out-of-Phase Clock Output Fully Assembled and Tested Ordering Information PART TEMP RANGE IC PACKAGE MAX16818EVKIT+ 0C to +70C* 28 TQFN-EP** +Denotes a lead-free and RoHS-compliant EV kit. *This limited temperature range applies to the EV kit PCB only. The MAX16818 IC temperature range is -40C to +125C. **EP = Exposed paddle. Component List DESIGNATION QTY C1 1 C2 1 C3 1 C4 1 C5 1 C6, C7 2 C8, C10 0 C9 1 C11 1 DESCRIPTION 2.2F 10%, 50V X7R ceramic capacitor (1206) Murata GRM31CR71H225K 1F 20%, 50V X7R ceramic capacitor (0805) Murata GRM21BR71H105M 4.7F 10%, 6.3V X7R ceramic capacitor (0603) Murata GRM188R70J475K 0.47F 10%, 6.3V X7R ceramic capacitor (0603) Murata GRM188R70J474K 1000pF 10%, 50V X7R ceramic capacitor (0603) Murata GRM188R71H102K 10F 10%, 50V X7R ceramic capacitors (2220) Murata GRM55DR71H106K Not installed, capacitors (0603) 0.22F 10%, 16V X7R ceramic capacitor (0603) Murata GRM188R71C224K 2200pF 10%, 50V X7R ceramic capacitor (0603) Murata GRM188R71H222K DESIGNATION QTY C12 1 C13 1 C14 1 D1 1 JU1 JU2 1 1 L1 1 N1 1 N2-N5 4 P1 1 DESCRIPTION 0.1F 10%, 16V X7R ceramic capacitor (0603) Murata GRM188R71C104K 100pF 5%, 50V C0G ceramic capacitor (0603) Murata GRM1885C1H101J 100F, 50V electrolytic capacitor (8mm x 10.2mm) Panasonic EEEFK1H101P 60V, 2A Schottky diode (SMB) Diodes Inc. B260-13-F 3-pin header 2-pin header 8.8H, 4ADC inductor Sumida CDEP105-8R8 40V, 4.9A n-channel MOSFET (SO8) Vishay Si4446DY 60V, 115mA n-channel MOSFETs (SOT23) Central Semiconductor 2N7002 LEAD-FREE -20V, -3.8A p-channel MOSFET (TSOP-6) Vishay Si3467DV-T1-E3 ________________________________________________________________ Maxim Integrated Products 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. 1 Evaluates: MAX16818 General Description MAX16818 Evaluation Kit Evaluates: MAX16818 Component List (continued) DESIGNATION QTY DESCRIPTION Q1 1 Q2 1 R1 R2 R3, R7, R15, R16 R4, R5 R6 R8 R9 R10 R11 R12, R13 1 1 NPN bipolar transistor (SOT223) Fairchild Semiconductor PZT3904 PNP bipolar transistor (SOT23) Fairchild Semiconductor MMBT3906 1k 1% resistor (1206) 12.1k 1% resistor (0603) 4 10k 1% resistors (0603) 2 1 1 1 1 1 2 R14 1 R17 1 1 1% resistors (0603) 4.99k 1% resistor (0402) 221k 1% resistor (0402) 100k 1% resistor (0402) 12.4k 1% resistor (0402) 105k 1% resistor (0603) 1k 5% resistors (0805) 0.007 2%, 0.5W sense resistor (2010) IRC LRC-LRF2010LF-01-R007-G 1k 1% resistor (0603) DESIGNATION QTY DESCRIPTION R18 R19 1 1 R20 1 R21 R22 1 1 R23 1 U1 1 U2 1 U3, U4 2 -- -- 2 1 2k 1% resistor (0603) 499 1% resistor (0603) 0.11 1%, 0.5W sense resistor (1206) IRC LRC-LRC1206LF-01-R11-F 30.1k 1% resistor (0603) 40.2k 1% resistor (0603) 100k SMT cermet trimmer, 11 turns MAX16818ATI+ (28-pin TQFN-EP, 5mm x 5mm) Voltage-output, high-side currentsense amplifier MAX4073TAXK+ (5-pin SC70-5) Low-voltage, adjustable precision shunt regulators (SOT23) Texas Instruments TL431AQDBZRQ1 Shunts PCB: MAX16818 Evaluation Kit+ Component Suppliers SUPPLIER PHONE WEBSITE Central Semiconductor 631-435-1110 www.centralsemi.com Diodes Inc. 805-446-4800 www.diodes.com Fairchild Semiconductor 888-522-5372 www.fairchildsemi.com IRC, Inc. 361-992-7900 www.irctt.com Murata Mfg. Co., Ltd. 770-436-1300 www.murata.com Panasonic Corp. 800-344-2112 www.panasonic.com Sumida Corp. 847-545-6700 www.sumida.com Vishay/Vitramon 203-268-6261 www.vishay.com Note: Indicate that you are using the MAX16818 when contacting these component suppliers. 2 _______________________________________________________________________________________ MAX16818 Evaluation Kit Recommended Equipment Before beginning, the following equipment is needed: * 6V to 28V, 5A DC power supply * A series-connected LED string rated at 1A (maximum voltage on the string should not exceed 18V) * A current probe to measure LED current * One voltmeter Procedure The MAX16818 EV kit is fully assembled and tested. Follow the steps below to verify board operation. Caution: Do not turn on the power supply until all connections are completed. 1) Verify that a shunt is installed across pins 2-3 of jumper JU1. 2) Verify that no shunt is installed across jumper JU2 (EV kit on). 3) Connect the anode end of the LED string to the LED+ pad. 4) Connect the cathode end of the LED string to the LED- pad. 5) Clip on the current probe across the string wires to measure the LED current. 6) Connect the positive terminal of the power supply to the VIN pad on the EV kit. Connect the negative terminal of the power supply to the PGND pad next to the VIN pad. 7) Turn on the power supply and increase the voltage to 6V or above. 8) Verify that the LED string current is approximately 1A. Adjust potentiometer R23 to obtain 1A. 9) Measure the voltage between the LED+ to LEDPCB pads. Detailed Description The MAX16818 EV kit is designed to evaluate the MAX16818 PWM LED driver controller in a buck-boost configuration. The EV kit PCB is designed with two layers and has 1oz copper traces. All components on the EV kit are installed on the top layer. The EV kit includes an on-board VCC regulating circuit for operation with input voltage between 6V to 8V. The EV kit also includes on-board output overvoltage protection circuitry to limit the output voltage. Input-Voltage Range The MAX16818 EV kit can operate from a DC supply voltage of 6V to 28V and requires at least 5A. The inputvoltage range is jumper selectable (see the Jumper Selection section). Transistor Q1, shunt regulator U3, and resistors R1, R2, and R3 are used to regulate VCC to 5V when the input voltage to the EV kit is between 6V to 8V. If the minimum input voltage is 8V, jumper JU1 can be replaced by a shorting wire between pins 1-2. Transistor Q1, shunt regulator U3, and resistors R1, R2, and R3 can be omitted from the EV kit, saving components and reducing the required PCB space. Output Current Range The MAX16818 EV kit can deliver up to 1A into an 18V series LED string. The maximum output current is configurable by sense resistor R14. The LED current can be adjusted from 400mA to 1A using potentiometer R23. LED Brightness Dimming The LED brightness can be dimmed using a TTL PWM signal with a frequency range of 80Hz to 5kHz. Connect the TTL dimming signal to the PWMDIM and GND pads to control the brightness of the LEDs. Output Overvoltage Protection The MAX16818 EV kit features overvoltage protection circuitry to limit the voltage from LED+ to GND to 46V when the LED string is opened. The overvoltage protection circuitry consists of resistors R6-R10, transistor Q2, and shunt regulator U4. The overvoltage protection circuitry is nonlatching. Switching Frequency The MAX16818 EV kit switching frequency (fSW) is configured to 600kHz by resistor R11. To reconfigure the MAX16818 switching frequency from 125kHz to 1.5MHz, replace resistor R11 using the equation below: For 120k R11 500k (6.25 x 10 ) R11 = 10 fSW For 40k R11 120k (6.40 x 10 ) 10 R11 = fSW where fSW is the desired switching frequency in Hz. Note: Other component values may need to be changed for proper operation. Refer to the MAX16818 IC data sheet for additional information. _______________________________________________________________________________________ 3 Evaluates: MAX16818 Quick Start Evaluates: MAX16818 MAX16818 Evaluation Kit Clock Output Output Enable (EN) The MAX16818 EV kit also features a digital clock output that is 180 out-of-phase with respect to the highside driver, N1. The clock output is available at the CLKOUT PCB pad. Jumper JU2 controls the output enable pin on the MAX16818 IC. The MAX16818 output enable pin (EN) is also connected to the overvoltage protection circuitry on the EV kit (see Table 2 for shunt positions). Jumper Selection Input-Voltage Range (VIN) Jumper JU1 selects the input-voltage range for the MAX16818 EV kit (see Table 1 for shunt positions). Table 2. JU2 Jumper Selection (EN) SHUNT POSITION EN PIN CONNECTED TO EV KIT FUNCTION Installed GND Disabled Overvoltage protection circuitry (R6-R10, Q2, U4) Enabled Table 1. JU1 Jumper Selection (IN) SHUNT POSITION IN PIN CONNECTED TO VIN VOLTAGE RANGE Not installed* 1-2 VIN 8V to 28V* *Default position. 2-3** VCC 6V to 28V None (Not allowed) No connect 0V *When operating in the 8V to 28V input-voltage range, jumper JU1 can be replaced by a shorting wire between pins 1-2. **Default position. 4 _______________________________________________________________________________________ _______________________________________________________________________________________ PGND R8 221k 1% Q2 C14 100F 50V 3 2 1 R6 4.99k 1% 5 2 2 R10 12.4k 1% R9 100k 1% VCC U3 1 C1 2.2F 50V VIN 5 1 U4 R7 10k 1% R3 10k 1% 3 2 4 CLKOUT SGND ENABLE 1 R2 12.1k 1% R1 1k 1% 2 3 1 JU2 R5 1 1% R4 1 1% Q1 R11 105k 1% C5 1000pF C4 0.47F C3 4.7F C2 1F VCC JU1 14 12 9 11 4 28 27 26 7 3 10 13 MAX16818 U1 SENSE- SENSE+ DIFF EAN EAOUT CLP CSN CSP LX DH 1 8 22 25 15 PGND SGND SGND SGND OVI LIM RT/SYNC CLKOUT EN BST VDD VCC IN N.C. N.C. DL PGOOD V_IOUT 2 L1 8.8H 23 24 19 18 17 16 20 21 5 6 4 5 R17 1k 1% 2 2 3 3 1 R22 40.2k 1% 2 3 N4 1 C13 100pF R21 30.1k 1% 2 3 N3 1 R19 499 1% C7 10F 50V VCC C9 0.22F C6 10F 50V R23 100k C8 OPEN C11 2200pF R18 2k N5 1% R14 0.007 2% 8 7 N1 3 2 R16 10k 1% C10 OPEN 1 6 D1 1 VCC 1 OUT VIN 1 U2 MAX4073T 5 RS- 2 N2 3 3 1 2 GND 2 4 RS+ 3 VCC R13 1k R12 1k R20 0.11 1% SGND R15 10k 1% PWMDIM 4 VCC P1 6 5 C12 0.1F LED- LED+ Evaluates: MAX16818 VIN MAX16818 Evaluation Kit Figure 1. MAX16818 EV Kit Schematic 5 Evaluates: MAX16818 MAX16818 Evaluation Kit Figure 2. MAX16818 EV Kit Component Placement Guide-- Component Side Figure 3. MAX16818 EV Kit PCB Layout--Component Side Figure 4. MAX16818 EV Kit PCB Layout--Solder Side 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. 6 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. Boblet