19-4012; Rev 0; 3/06 MAX15000A Evaluation Kit The MAX15000A evaluation kit (EV kit) is a fully assembled and tested circuit board that contains a 9W flyback DC-DC converter. The circuit is configured for +5V and +15V output voltages and provides up to 1.5A and 100mA of current at each respective output. Power for the circuit can be provided from either a +36V to +72V or a -36V to -72V DC source. High efficiency up to 81% is achieved using a flyback DC-DC converter topology. The surface-mount transformer provides up to 1500V galvanic isolation for both outputs. Low cost is achieved through the use of primary-side regulation while undervoltage lockout (UVLO) and digital soft-start provide for a robust 9W isolated power supply. Operation at 350kHz allows the use of small magnetics and output capacitors. Warning: The MAX15000A 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 +36V to +72V or -36V to -72V DC Input Range Isolated Outputs VOUT1: +5V Provides Up to 1.5A VOUT2: +15V Provides Up to 100mA 5% (typ) Load Regulation for the +5V Output Set Point (150mA to 1.5A) 81% Efficiency at 48V Input and Full Load Cycle-by-Cycle Current Limit 350kHz Switching Frequency Digital Soft-Start High-Accuracy Undervoltage Lockout (UVLO) Undervoltage Lockout Open-Drain Flag Output Designed for 1500V Isolation with Primary-Side Regulation Low-Cost Flyback Design Fully Assembled and Tested Ordering Information PART TEMP RANGE IC PACKAGE MAX15000AEVKIT 0C to +70C 10 MAX(R) MAX is a registered trademark of Maxim Integrated Products, Inc. Component List DESIGNATION QTY C7, C11 2 0.22F 10%, 50V X7R ceramic capacitors (0805) Murata GRM21BR71H224KA01B C8, C10, C19 0 Not installed, ceramic capacitors (0603) 1 22F 20%, 6.3V X5R ceramic capacitor (1206) TDK C3216X5R0J226M C9 1 100pF 2%, 50V C0G ceramic capacitor (0603) Murata GRM1885C1H101G C5 1 47F, 25V electrolytic capacitor (6.3mm x 5.8mm) Panasonic EEVFK1E470P C12 1 15F 10%, 35V tantalum capacitor (D) Kemet T491D156K035AS C6 1 0.0047F 10%, 250VAC X7R ceramic capacitor (1825) Murata GA355DR7GC472KY02L C13 1 1F 10%, 16V X7R ceramic capacitor (0805) TDK C2012X7R1C105KT DESIGNATION QTY DESCRIPTION C1, C2 2 1F 10%, 100V X7R ceramic capacitors (1812) TDK C4532X7R2A105K C3 1 68F, 6.3V electrolytic capacitor (V) Kemet A700V686M006ATE028 C4 DESCRIPTION ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. 1 Evaluates: MAX15000A General Description MAX15000A Evaluation Kit Evaluates: MAX15000A Component List (continued) DESIGNATION QTY C14 1 C15 3900pF 10%, 50V X7R ceramic capacitor (0603) Murata GRM188R71H392K 1F 10%, 25V X7R ceramic capacitor (0805) TDK C2012X7R1E105KT DESIGNATION QTY DESCRIPTION D8 1 40V, 0.5A Schottky diode (SOT23) Zetex ZHCS500 JU1 1 2-pin header L1 1 3A ferrite bead inductor (1806) Fair-Rite 2518066007Y3 L2 1 100mA ferrite bead inductor (0805) Fair-Rite 2508051027Y0 N1 1 200V, 1.2A n-channel MOSFET (SO-8) IR IRF7464 C16 1 1F 10%, 50V X7R ceramic capacitor (1206) Murata GRM31MR71H105K C17 0 Not installed, ceramic capacitor (0805) R1 1 22.6k 1% resistor (0603) R2 1 2.49k 1% resistor (0603) 1 1.37M 1% resistor (0805) 1 0.1F 10%, 25V X7R ceramic capacitor (0603) Murata GRM188R71E104K R3 C18 R4 1 51.1k 1% resistor (0805) R5 1 0.600 1% power resistor (1206) IRC LRC-LR1206-01-R600-F 33k 5% resistor (1206) D1 D2 D3 1 1 0 40V, 10A Schottky diode (POWERMITE 3) Diodes Inc. SBM1040 200V, 1.5A super-fast diode (SMD) Vishay BYG20D Not installed, 250V, 250mA highvoltage switching diode (SOD-123) Central Semiconductor CMHD2003 recommended R6 1 R7, R12 2 1.2k 5% resistors (1206) R8 0 Not installed, resistor (1206) R9 1 75k 1% resistor (0603) R10 1 4.7 5% resistor (0805) R11 1 100 5% resistor (0603) R13 1 10k 5% resistor (0805) R14 1 14.3k 1% resistor (0805) R15 1 750 5% resistor (0603) 1 28H, 10W, 1:0.536:0.214:0.429 turn 350kHz transformer (10-pin gull wing) Coiltronics CTX03-17492-R 1 5.6V, 0.5W zener diode (SOD-123) Diodes Inc. BZT52C5V6 D5 1 18V, 0.5W zener diode (SOD-123) Diodes Inc. BZT52C18 T1 D6 1 75V, 250mA high-speed diode (SOT23) Central Semiconductor CMPD914 U1 1 MAX15000AEUB+ (10-pin MAX) -- 1 Shunt, JU1 -- 4 Rubber bumpers -- 1 MAX15000A EV kit PC board D4 D7 2 1 DESCRIPTION 0 Not installed, 14V, 250mW zener diode (SOD-323) Central Semiconductor CMDZ5244B recommended _______________________________________________________________________________________ MAX15000A Evaluation Kit SUPPLIER PHONE WEBSITE Central Semiconductor 631-435-1110 www.centralsemi.com Cooper-Coiltronics 561-752-5000 www.cooperet.com Dale-Vishay 402-564-3131 www.vishay.com Diodes Inc. 805-446-4800 www.diodes.com Fair-Rite Products 845-895-2055 www.fair-rite.com International Rectifier 310-322-3331 www.irf.com IRC 361-992-7900 www.irctt.com Kemet 864-963-6300 www.kemet.com Murata 770-436-1300 www.murata.com Panasonic 714-373-7366 www.panasonic.com TDK 847-803-6100 www.component.tdk.com Vishay 402-563-6325 www.vishay.com Zetex USA 631-543-7100 www.zetex.com Note: Indicate that you are using the MAX15000A when contacting these component suppliers. Quick Start Required Equipment * 36V to 72V power supply capable of providing up to 1A * Two voltmeters * 22F, 100V bulk storage capacitor to be connected to the input terminals of the EV kit The MAX15000A EV kit is fully assembled and tested. Follow these steps to verify board operation. Do not turn on the power supply until all connections are completed. Outputs 1) Connect a voltmeter to the VOUT1 SGND pads. 2) Connect a second voltmeter to the VOUT2 and SGND pads. 3) Connect a 750mA load to VOUT1 and a 50mA load to VOUT2. 4) Verify that a shunt is not installed across the pins of jumper JU1 (SHDN). 5) Connect the power supply's positive terminal to the +VIN pad. Connect the power supply's ground to the -VIN pad. 6) Turn on the power supply above +36V and verify that the voltmeter at VOUT1 reads approximately +5V. 7) Verify that the voltmeter at VOUT2 reads approximately +15V. The maximum current for each output should be limited to less than 1.5A for VOUT1 and 100mA for VOUT2. For instructions on selecting the feedback resistors for other output voltages, see the Evaluating Other Output Voltages, Current Limits, and Undervoltage Lockouts section. Detailed Description The MAX15000A EV kit is a 9W, isolated flyback DC-DC converter that provides a +5V output and a +15V output. The +5V output, VOUT1, can provide up to 1.5A and the +15V output, VOUT2, can provide up to 100mA. The circuit can be powered from a +36V to +72V or a -36V to -72V DC source. The user must supply at least 22F of bulk storage capacitance at the input terminals (+VIN, -VIN). The capacitor should be rated for 100V and be able to carry approximately 200mA of ripple current. The flyback DC-DC converter achieves up to 81% efficiency. The single-transistor topology and primary-side regulation provide for a low-cost design by eliminating _______________________________________________________________________________________ 3 Evaluates: MAX15000A Component Suppliers Evaluates: MAX15000A MAX15000A Evaluation Kit the need for an optocoupler and shunt reference on the secondary side. The MAX15000A EV kit provides cycleby-cycle, primary-side current-limit protection. Currentsense resistor, R5, senses the current through the transformer's (T1) primary winding, switching transistor (N1), and turns off the transistor when the trip level of 1V is reached. The surface-mount transformer provides galvanic isolation up to 1500V for both outputs. The MAX15000A EV kit features PC board pads for an RCD snubber network (R8, C10, D3) to minimize leakage energy ringing and clamp the voltage at the drain of MOSFET N1 during switching (with most MOSFETs this snubber circuit can be eliminated). Primary-side regulation through feedback resistors R1 and R2, rectifier D6, and transformer T1 tertiary windings provide 5% regulation for the 5V output set point. Resistors R7 and R12 are adjusted to preload the tertiary winding for the desired +5V ouput set point and regulation. UVLO provides controlled turn-on and shutdown during brownouts, powering up, or powering down. The UVLO settings can be changed by replacing resistor R3. Startup resistor R6 and reservoir capacitor C16 enable the MAX15000A to start up within approximately 37ms. The digital soft-start allows the output voltage to slowly ramp up in a controlled manner within 6ms. The MAX15000A controller switches at a fixed 350kHz frequency and is set by resistor-capacitor networks R14, R15/C18, and C19. The switching duty cycle is varied to control energy transfer to the isolated outputs. The maximum duty cycle is 50% for the EV kit's discontinuous current-mode flyback design. Shutdown Mode (Jumper and Remote Control Methods) The MAX15000A EV kit features two methods to shut down the flyback DC-DC converter. Jumper JU1 can be used to shut down the flyback DC-DC converter. An alternate method, remote control shutdown, can be done with a user-supplied open-collector/drain transistor or relay contact connected to the SHDN and -VIN pads of the EV kit. Table 1 lists the shutdown mode. 4 Table 1. Jumper JU1 Shutdown Mode SHUNT LOCATION Open Installed MAX15000A UVLO/EN PIN MAX15000A OUTPUT UVLO resistors R3 and R4 determine startup voltage MAX15000A enabled Pulled low to -VIN Shutdown mode Evaluating Other Output Voltages, Current Limits, and Undervoltage Lockouts VOUT1 and VOUT2 Output Voltages The MAX15000A EV kit's outputs VOUT1 and VOUT2 are set to +5V and +15V, respectively, by the transformer T1 tertiary windings, the transformer's respective secondary output windings, and the resistor-divider R1 and R2. To generate scaled output voltages other than +5V (+4.2V to +6.8V) and +15V (+12.3V to +20.2V), select different voltage-divider resistors (R1, R2). Resistor R2 is typically chosen to be less than 5k. When evaluating other output voltages, verify that the secondary outputs' components affected by increased voltage are rated for the appropriate voltage. Components C3, C4, C13, and D4 of VOUT1 and components C5, C15, and D5 should have their respective voltage rating evaluated. Using the desired scaled output voltages, resistor R1 is then found by the following equation: R1 = [[{(VOUT1 - VVD1) x NT / N1} - VVD6] / VFB -1] x R2 where VOUT1 is the +5V output, NT = 15 is the transformer's tertiary turns N1 = 6 is the transformer's secondary VOUT1, +5V output turns VFB = 1.23V is the MAX15000A reference voltage VVD6 = 1.0V is the circuit's tertiary winding, high-speed diode D6 forward voltage drop V VD1 = 0.45V (typ) is the circuit's secondary-side Schottky diode D1 forward voltage drop at 1.5A Both output voltages will be scaled up or down since the respective transformer's secondary output turns set the actual voltage. Additionally, the maximum current for each output should be limited to less than 1.5A for VOUT1 and 100mA for VOUT2. _______________________________________________________________________________________ MAX15000A Evaluation Kit Undervoltage Lockout (UVLO) The MAX15000A EV kit features an accurate UVLO circuit that prevents operation below the programmed input-supply start voltage. Resistors R3 and R4 set the voltage at the MAX15000A's UVLO/EN pin that deter- mines the UVLO wake-up and shutdown levels, 1.23V (typ) and 1.17V (typ), respectively. To evaluate other wake-up and shutdown levels, replace resistor R3 with another surface-mount resistor (0805 size). Refer to the Undervoltage Lockout section in the MAX15000/ MAX15001 data sheet for instructions on selecting resistor R3 as determined by the following equation: R3 = ((VIN - VUVLO) / VUVLO) x R4 where VIN is the 36V to 72V supply voltage applied between the +VIN and -VIN pads of the EV kit and VUVLO = 1.23V (typ). UVLO Flag (UFLG and FLG_PULL) The MAX15000A EV kit features an open-drain UVLO flag output at the UFLG PC board pad. The UFLG signal can be used to indicate a UVLO condition has occurred. A voltage source of up to 25V can be connected to the PC board's FLG_PULL pad, which, along with resistor R13, pulls up the UFLG signal. Refer to the UVLO Flag (UFLG) section in the MAX15000/MAX15001 data sheet for instructions and additional information on using the UFLG pin of the MAX15000A. _______________________________________________________________________________________ 5 Evaluates: MAX15000A Current Limiting The EV kit features current limiting for the transformer's primary current. The MAX15000A IC turns off switching MOSFET N1 when the voltage at the MAX15000A CS pin reaches 1V. Current-sense resistor R5 (0.6) limits the transformer peak primary current to 1.67A (1V / 0.6 = 1.67A). This limits the average short-circuit current on the secondary outputs typically to 1.42A (average with IOUT2 = 100mA) and 0.52A (average with IOUT1 = 1.5A) for VOUT1 and VOUT2, respectively. To evaluate a lower current limit, current-sense resistor R5 must be replaced with a different surface-mount resistor (1206 size) as determined by the following equation. When considering the transformer's primary input current: R5 = (VSENSE / IPRIMARY) where VSENSE = 1V and IPRIMARY is the transformer's maximum primary current. Flyback Converter Waveforms EFFICIENCY vs. OUTPUT CURRENT OUTPUT TURN-0N VOLTAGE TRANSIENT 90 VOUT2 = +15V, 100mA 80 VOUT1 2V/div EFFICIENCY (%) 70 60 50 VOUT2 = +15V, 25mA 40 VOUT2 30 5V/div 20 10 0 0 0.3 0.6 0.9 1.2 1.5 2ms IOUT1 (A) Figure 1. Efficiency vs. Output Current IOUT1 (+VIN = 48V) Figure 2. Output Voltage Transient at Power-Up (+VIN = 48V, Channel 1 = VOUT1 (IOUT1 = 150mA), Channel 2 = VOUT2 (IOUT2 = 25mA)) VOUT1 REGULATION vs. IOUT1 VOUT2 REGULATION vs. IOUT2 6.0 18.0 5.8 17.6 VOUT2 = +15V, 25mA 5.6 17.2 5.4 16.8 5.2 16.4 5.0 VOUT2 (V) VOUT1 (V) Evaluates: MAX15000A MAX15000A Evaluation Kit VOUT2 = +15V, 100mA 4.8 15.6 15.2 4.4 14.8 4.2 14.4 VOUT1 = +5V, 1.5A 14.0 0 0.3 0.6 0.9 1.2 IOUT1 (A) Figure 3. VOUT1 (+5V) Output Voltage Regulation 6 16.0 4.6 4.0 VOUT1 = +5V, 150mA 1.5 0 0.02 0.04 0.06 0.08 0.10 IVOUT2 (A) Figure 4. VOUT2 (+15V) Output Voltage Regulation _______________________________________________________________________________________ R1 22.6k 1% R4 51.1k R3 1.37M 1% SHDN C17 OPEN R2 +VIN 2.49k 1% FB_P -VIN 2 1 36V TO 72V +VIN +VIN JU1 C9 100pF C2 1F 100V C7 0.22F C14 3900pF R13 10k FLG_PULL UFLG R9 75k 1% C1 1F 100V R6 33k C16 1F D8 2 9 1 4 3 UVLO/EN UFLG VCC U1 IN RT GND CS NDRV R7 1.2k MAX15000A C12 15F 35V COMP FB FB_P 6 7 5 8 10 R12 1.2k IN R14 14.3k 1% C8 OPEN 1 C18 0.1F R15 750 R11 100 56 4 15T 2 4 1 2 3 3 C19 OPEN R5 0.600 1% 7 6 8 5T 10 12T 5 T1 9 8 N1 IRF7464 7 28T 28H L2 D3 OPEN C10 OPEN C11 0.22F R10 4.7 R8 OPEN D7 OPEN D6 C6 0.0047F 250VAC D1 D2 C3 68F 6.3V C5 47F 25V D4 D5 L1 C13 1F C15 1F C4 22F SGND 6.3V VOUT1 SGND VOUT2 Evaluates: MAX15000A IN MAX15000A Evaluation Kit Figure 5. MAX15000A EV Kit Schematic _______________________________________________________________________________________ 7 Evaluates: MAX15000A MAX15000A Evaluation Kit Figure 6. MAX15000A EV Kit Component Placement Guide--Component Side Figure 7. MAX15000A EV Kit PC Board Layout--Component Side 8 _______________________________________________________________________________________ MAX15000A Evaluation Kit Evaluates: MAX15000A Figure 8. MAX15000A EV Kit PC Board 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, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9 (c) 2006 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.