MAX15005A Evaluation Kit. Evaluates: MAX15005A

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1 9-0964; Rev 0; 8/07 MAX5005A Evaluation Kit General Description The MAX5005A evaluation kit (EV kit) is a fully assembled and tested PCB that contains an W flyback DC- DC converter for vacuum-fluorescent displays (VFDs) in automotive applications. The circuit uses a MAX5005A high-performance, current-mode pulse-width modulation (PWM) controller in a 6-pin TSSOP package. The EV kit circuit is configured for output voltages of 3V, 60V, and 0V, and provides up to 650mA, ma, and 55mA of current from the respective output. Additionally, a 5V lowdropout (LDO) voltage regulator output is provided that can source up to 5mA. Power for the EV kit circuit is provided from a 6.5V to 6V DC source. The MAX5005A EV kit input circuit can sustain a 40V transient. High efficiency of up to 7 is achieved using a singletransistor flyback DC-DC converter topology. Low cost is achieved through the use of direct secondary-side regulation that does not require optical couplers. Input undervoltage lockout (UVLO), output overvoltage protection (OVP), and soft-start provide for a robust W power supply. Operation at 00kHz minimizes the size of the transformer and passive components. Warning: The MAX5005A EV kit is designed to operate with high voltages. Dangerous voltages are present on this EV kit and on equipment connected to it. Users who power up this EV kit, or power the sources connected to it, must be careful to follow safety procedures appropriate to working with high-voltage electrical equipment. Under severe fault or failure conditions, this EV kit may dissipate large amounts of power, which could result in the mechanical ejection of a component or of component debris at high velocity. Operate this kit with care to avoid possible personal injury. Features 6.5V to 6V DC Input Range Outputs 3V Provides Up to 650mA (VFD Filament) 60V Provides Up to ma (VFD Grid) 0V Provides Up to 55mA (VFD Anode) Output Voltage Accuracy 0V (Anode) = ±3% (Regulated Output) 60V (Grid) = ±5% (Proportional Loading) 3V (Filament) = ±0% (Proportional Loading) 7 Efficiency at 6V Input and Full Load 5V LDO Output Provides Up to 5mA Hiccup Current-Limit and Overtemperature Shutdown 00kHz Switching Frequency Capacitor Adjustable Soft-Start High-Accuracy Undervoltage Lockout (UVLO) Output Overvoltage Protection (OVP) Capable of Synchronizing to an External Clock Low-Cost, Robust Flyback Design Fully Assembled and Tested PART MAX5005AEVKIT+ +Denotes lead-free and RoHS-compliant. Ordering Information TYPE EV Kit Component List C 330µF, 50V electrolytic capacitor (.5mm x 3.5mm) Panasonic EEVFKH33Q C4 00pF ±%, 50V C0G ceramic Murata GRM885CH0G C 0.µF ±0%, 50V X7R ceramic Murata GRM88R7H04K C5 000pF ±5%, 50V C0G ceramic Murata GRM885CH0J C3, C0 µf ±0%, 6V X7R ceramic capacitors (0805) Murata GRMBR7C05K C6 4700pF ±0%, 50V X7R ceramic Murata GMR88R7H47K Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at , or visit Maxim s website at

2 MAX5005A Evaluation Kit C7 C8 C9 C C, C4 C3 C5 C6 C7 C8 D D D3 47pF ±5%, 50V C0G ceramic Murata GRM885CH470J 0.68µF ±0%, 6V X7R ceramic capacitor (0805) Murata GRM9R7C684K 560pF ±5%, 50V C0G ceramic Murata GRM885CH56J 00pF ±0%, 00V X7R ceramic Murata GRM88R7AK 00pF ±0%, 63V C0G ceramic capacitors (06) TKD C36C0GJ0K 0µF, 00V electrolytic capacitor (0mm x 0.5mm) SANYO 00CE0FS µf, 80V electrolytic capacitor (8mm x 0.mm) Panasonic EEEFKK0P 330µF, 6.3V electrolytic capacitor (8mm x 0.5mm) SANYO 6CE330EX.µF ±0%, 0V X5R ceramic AVX 0603ZD5MAT 4700pF ±0%, 00V X7R ceramic capacitor (0805) Murata GRM9R7A47K 00V, A super-fast diode (SMA) Diodes Inc. ESB-3-F 600V, A super-fast diode (SMB) Diodes Inc. MURS60-F 400V, A super-fast diode (SMA) Diodes Inc. MURS40-3-F Component List (continued) D4 40V, 3A Schottky diode (SMA) Diodes Inc. B340A-3-F D5 8.V, 350mW ±5% Zener diode (SOT3) Central Semiconductor CMPZ537B JU, JU -pin headers JU3 3-pin header N 80V,.4A n-channel M OS FE T ( 8- p i n S O) Vishay Si4896DY-T-E3 R.5kΩ ± resistor (0603) R 560Ω ±5% resistor (0) R3 5Ω ±5% resistor (0805) R4 40kΩ ± resistor (0603) R5 kω ±5% resistor (0603) R Ω ± power resistor (00) IRC LRC-LR00LF-0-R070-F R7 50Ω ±5% resistor (06) R8 00kΩ ±5% resistor (06) R9 0Ω ±5% resistor (06) R0 36kΩ ±5% resistor (06) R.33MΩ ± resistor (0603) R.kΩ ± resistor (0603) R3 8kΩ ± resistor (0603) R4.33kΩ ± resistor (0603) R5 00Ω ±5% resistor (0805) R6 0Ω ±5% resistor (0) R7 87kΩ ± resistor (0603) R8 47.5kΩ ± resistor (0603) R9 0kΩ ±5% resistor (0805) R0 3kΩ ± resistor (0603) T 5µH, 0W, :3.438:.83:0.88 turn, 00kH z tr ansfor m er ( 0- p i n g ul l w i ng ) Coiltronics CTX R U M AX 5005AAU E + ( 6- p i n TS S O P - E P ) Shunts (JU, JU, JU3) PCB: MAX5005A Evaluation Kit+

3 MAX5005A Evaluation Kit SUPPLIER PHONE WEBSITE AVX Corp Central Semiconductor Cooper Electronic Tech./Coiltronics Diodes Inc IRC Murata Mfg. Co., Ltd Panasonic Corp SANYO Corp Vishay Note: Indicate that you are using the MAX5005A when contacting these component suppliers. Quick Start Required Equipment Before beginning, the following equipment is needed: One 6.5V to 6V power supply capable of providing up to 3A Three voltmeters Procedure (Outputs) The MAX5005A 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. ) Connect a voltmeter to the FILAMENT+ and FILA- MENT- pads. ) Connect the second voltmeter to the V_GRID and pads. 3) Connect the third voltmeter to the and pads. 4) Verify that a shunt is installed across the pins of jumpers JU (ON/OFF) and JU (SYNC). 5) Verify that a shunt is installed across pins -3 of jumper JU3 (OVP). 6) Connect the power supply s positive terminal to the VIN pad. Connect the power supply s ground to the pad. 7) Turn on the power supply above 7V and verify the following voltmeters readings: FILAMENT = 3V V_GRID = 60V = 0V The maximum current for each output should be limited Component Suppliers to less than 650mA, ma, and 55mA for each respective output detailed above in step 7. Detailed Description The MAX5005A EV kit is an W flyback DC-DC converter that provides output voltages of 3V at up to 650mA, 60V at up to ma, and 0V at up to 55mA. The MAX5005A flyback power supply is designed to provide power to automotive VFDs. The circuit can be powered from a 6.5V to 6V DC source, which provides 3A to the EV kit. The flyback DC-DC converter achieves up to 7 efficiency and the single-transistor topology provides for a lower-cost design. The MAX5005A EV kit provides cycle-by-cycle primary-side current-limit protection. Current-sense resistor R6 senses the current through the transformer s (T) primary winding, switching transistor (N), and turns off the transistor when the trip level of 0.3V is reached. The MAX5005A EV kit features a resistor/ capacitor/diode (RCD) snubber network (R, C, and D) to minimize leakage energy ringing and clamp the voltage at the drain of MOSFET N during switching. Secondary-side regulation through feedback resistors R3 and R4 provide ±3% regulation for the 0V output (V_Anode). Resistors R8, R0, and R5 preload the respective output and assist with overall regulation at minimum loading. UVLO provides controlled turn-on and shutdown during brownouts, power-up, or power-down. The UVLO setting can be changed by replacing resistor R8. The MAX5005A analog soft-start allows the output voltage to slowly ramp up in a controlled manner within 56ms and is set by capacitor C8. The OVP is provided by independently sensing the 0V output (V_Anode) through resistors R and R. 3

4 MAX5005A Evaluation Kit The MAX5005A controller switches at a fixed 00kHz frequency and is set by resistor/capacitor network R and C5. The switching duty cycle is varied to control energy transfer to the outputs. The maximum duty cycle is 50% for the EV kit s discontinuous current-mode flyback design. Shutdown Mode (Jumper- or Remote- Control Method) The MAX5005A EV kit features a jumper (JU) that can be used to shut down the flyback DC-DC converter. An alternate shutdown method (remote control) can be done with a user-supplied relay contact connected to pin of jumper JU of the EV kit. Table shows jumper options. Table. Jumper JU Shutdown Mode SHUNT POSITION Installed Not installed Not installed ON/OFF PIN UVLO resistors R7 and R8 determine startup voltage Pulled low to through resistor R8 Relay contacts connected between JU pin MAX5005A EV KIT OUTPUT MAX5005A enabled Shutdown mode Remote mode SYNC Mode The MAX5005A can be synchronized to an external TTL/CMOS square-wave clock source. The -pin jumper (JU) selects the SYNC mode of operation or 00kHz internal frequency for the MAX5005A. Table shows jumper options. The TTL/CMOS square-wave clock source (from 05kHz to 30kHz) must provide the following signal qualities: Output voltage: Logic-low = 0 to 0.8V Logic-high = V to 5.5V Output frequency = 05kHz to 30kHz Minimum positive-pulse width = 50ns Connect the external square-wave clock to the SYNC and pads. Refer to the MAX5005A data sheet for more information on the SYNC pin. Table. Jumper JU SYNC Mode Functions SHUNT POSITION Installed Not installed Evaluating Other Current Limits, Input UVLO, and Output OVP Shutdown Current Limiting The EV kit features current limiting for the transformer s primary current. The MAX5005A IC turns off switching MOSFET N when the voltage at the MAX5005A CS pin reaches 0.3V. Current-sense resistor R6 (0.07Ω) limits the transformer peak primary current to 4.A (0.3V / 0.07Ω = 4.A). To evaluate a lower current limit, current-sense resistor R6 must be replaced with a different surface-mount resistor (00 size), as determined by the following equation: R6 = (0.300V/I PRIMARY ) where I PRIMARY is the transformer s maximum peak primary current. Input UVLO (ON/OFF) The MAX5005A EV kit features a brownout and inputsupply startup UVLO circuit that prevents operation below the programmed input-supply-start voltage. Resistors R7 and R8 set the input UVLO threshold of the EV kit. To change the input UVLO voltage, replace resistor R7 (or R8) with another surface-mount resistor (0603 size). Using the desired startup voltage, resistor R7 is then found by the following equation: R7 SYNC PIN Connected to SGND Connected to an external TTL/CMOS square-wave clock source at the SYNC and SGND pads VINSTARTUP.30V = ( ) MAX5005A OPERATING MODE Internal clock mode (00kHz set by R and C5) Synchronization mode (synchronized to an external clock frequency) x R8 where VIN STARTUP is the desired startup voltage that the EV kit starts at, and resistor R8 is typically in the 50kΩ range (47.5kΩ default). Refer to the Startup Operation/UVLO/ON/OFF section of the MAX5005A data sheet for additional information on the ON/OFF pin of the MAX5005A IC. 4

5 MAX5005A Evaluation Kit Output OVP Shutdown The MAX5005A EV kit features an OVP circuit that prevents operation above the programmed output supply voltage (36V default). Jumper JU3 configures the circuit for output OVP protection when the shunt is placed across pins -3. Resistors R and R set the OVI threshold of the OVP circuit for the MAX5005A IC. To evaluate other OVP voltages, replace resistor R with another surface-mount resistor (0603 size). Using the desired OVP voltage, resistor R is then found by the following equation: R OVP.8V x R = ( ) where OVP is the desired voltage that the circuit shutdown is at and resistor R is typically in the 0kW range (.kω default). See Table 3 for configuring jumper JU3 for output OVP protection. Input OVP Shutdown (Load Dump Protection) The MAX5005A EV kit OVP circuit can be reconfigured to provide load dump protection for VIN when it rises above the programmed VIN supply voltage (4.7V default). Jumper JU3 configures the circuit for input OVP protection when the shunt is placed across pins -. Resistors R and R0 set the OVI threshold of the OVP circuit for the MAX5005A IC. To evaluate other OVP voltages, replace resistor R0 with another surface-mount resistor (0603 size). Using the desired OVP voltage, resistor R0 is then found by the following equation: R0 OVP.8V x R = ( ) where OVP is the desired voltage that the circuit shutdown is at and resistor R is typically in the 0kΩ range (.kω default). See Table 3 for configuring jumper JU3 for input OVP protection. Table 3. Jumper JU3 OVP Shutdown SHUNT POSITION OVI PIN - Sense VIN input -3*) Sense output OVP OPERATION Inp ut over vol tag e p r otecti on ( l oad d um p ) Output overvoltage protection Not installed No sensing OVP disabled *Default position. 5

6 MAX5005A Evaluation Kit 6 MAX5005A U T EP VIN V_GRID SGND IN N JU ON/OFF C 0.μF 50V R7 87kΩ R8 47.5kΩ R0 3kΩ C 330μF 50V C3 0μF 00V C8 0.68μF C7 47pF C6 4700pF SLOPE 4 C4 00pF C9 560pF R 560Ω R5 00Ω D C5 000pF VIN JU JU3 3 OVI 3 N.C. 5 RTCT 6 R.33MΩ R.5kΩ R.kΩ R9 0kΩ SGND 7 SYNC SYNC 8 R5 kω R7 50Ω R8 00kΩ C 00pF D 7 0 FB 4 COMP CS R3 5Ω 5 OUT C0 μf 6V 3 9 SS C3 μf 6V 6 VCC R3 8kΩ R4 40kΩ R Ω C8 4700pF 00V R6 0Ω C 00pF 00V R4.33kΩ D3 D4 C4 00pF R9 0Ω R0 36kΩ C5 μf 80V FILAMENT+ FILAMENT- C6 330μF 6.3V D5 C7.μF 0V Figure. MAX5005A EV Kit Schematic

7 MAX5005A Evaluation Kit Figure. MAX5005A EV Kit Component Placement Guide Component Side Figure 3. MAX5005A EV Kit PCB Layout Component Side Figure 4. MAX5005A 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. Maxim Integrated Products, 0 San Gabriel Drive, Sunnyvale, CA Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. janet freed