19-2716; Rev 0a; 1/03 MAX5052A Evaluation Kit Features The MAX5052A evaluation kit (EV kit) is a fully assembled and tested circuit board that contains a 9W flyback DC-to-DC converter. The circuit is configured for output voltages of +5V and +15V and provides up to 1.5A and 100mA of current at each respective output. Power for the circuit can be provided from either a +36VDC to +72VDC or -36VDC to -72VDC source. High efficiency up to 83% is achieved using a singletransistor, flyback DC-to-DC converter topology. The surface-mount transformer provides up to 1500V galvanic isolation of both outputs. Low cost is achieved through the use of primary-side regulation while undervoltage lockout (UVLO), digital soft-start, and thermal shutdown provide for a robust 9W isolated power supply. ♦ +36VDC to +72VDC or -36VDC to -72VDC Input Voltage Range Operation at 262kHz allows the use of small magnetics and output capacitors. ♦ Undervoltage Lockout (UVLO) Warning: The MAX5052A EV kit is designed to operate with high voltages. Dangerous voltages are present on the MAX5052A EV kit and on equipment connected to it. Users who power up the MAX5052A EV kit or power the sources connected to it must be careful to follow safety procedures appropriate to working with highvoltage electrical equipment. Under severe fault or failure conditions, the MAX5052A 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 MAX5052A EV kit with care to avoid possible personal injury. ♦ Isolated Outputs VOUT1: +5V Provides Up to 1.5A VOUT2: +15V Provides Up to 100mA ♦ ±5% (typ) Load Regulation for the +5V Output (150mA to 1.5A) ♦ 83% Efficiency at 48V Input and Full Load ♦ Cycle-by-Cycle Current Limit ♦ 262kHz Switching Frequency ♦ Digital Soft-Start ♦ Designed for 1500V Isolation with Primary-Side Regulation ♦ Low-Cost Flyback Design ♦ Fully Assembled and Tested Ordering Information PART MAX5052AEVKIT TEMP RANGE 0°C to +70°C IC PACKAGE 8 µMAX Component Suppliers SUPPLIER PHONE FAX WEBSITE Central Semiconductor 631-435-1110 631-435-1824 www.centralsemi.com Cooper-Coiltronics 561-752-5000 561-742-1178 www.cooperet.com Dale-Vishay 402-564-3131 402-563-6296 www.vishay.com Diodes Inc. 805-446-4800 805-446-4850 www.diodes.com Fair-Rite Products 845-895-2055 845-895-2629 www.fair-rite.com International Rectifier 310-322-3331 310-726-8721 www.irf.com Kemet 864-963-6300 864-963-6322 www.kemet.com Murata 770-436-1300 770-436-3030 www.murata.com Panasonic 714-373-7366 714-737-7323 www.panasonic.com TDK 847-803-6100 847-390-4405 Telefunken-Vishay 402-563-6325 N/A www.vishay.com Zetex USA 631-543-7100 631-864-7630 www.zetex.com www.component.tdk.com Note: Please indicate that you are using the MAX5052A when contacting these component suppliers. ________________________________________________________________ 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: MAX5052A General Description Evaluates: MAX5052A MAX5052A Evaluation Kit Component List DESIGNATION QTY C1, C2 2 1µF ±10%, 100V X7R ceramic capacitors (1812) TDK C4532X7R2A105K C3 1 68µF, 6.3V electrolytic capacitor (V case) Kemet A700V686M006AT C4 1 22µF ±20%, 6.3V X5R ceramic capacitor (1206) TDK C3216X5R0J226M C5 C6 C7, C11, C12 47µF, 25V electrolytic capacitor (6.3 x 5.8) Panasonic EEVFK1E470P 1 0.0047µF ±10%, 250VAC X7R ceramic capacitor (2220) Murata GA355DR7GC472KY02L 3 0.22µF ±10%, 50V X7R ceramic capacitors (0805) Murata GRM21BR71H224KA01B C8, C10 0 Not installed, ceramic capacitors (0603) C9 1 2200pF ±10%, 50V X7R ceramic capacitor (0603) TDK C1608X7R1H222K C13 C14 C15 C16 C17 D1 2 1 DESCRIPTION 1 1 1 1 1µF ±10%, 16V X7R ceramic capacitor (0805) TDK C2012X7R1C105KT 0.022µF ±10%, 50V X7R ceramic capacitor (0603) TDK C1608X7R1H223KT 1µF ±10%, 25V X7R ceramic capacitor (0805) TDK C2012X7R1E105KT 15µF ±10%, 35V tantalum capacitor (D case) Kemet T491D156K035AS 0 Not installed, ceramic capacitor (0805) 1 40V, 10A Schottky diode (POWERMITE 3) Diodes Inc. SBM1040 DESIGNATION QTY DESCRIPTION D2 1 200V, 1.5A super-fast diode (SMD) Vishay/Telefunken BYG20D D3 0 Not installed; 250V, 250mA highvoltage switching diode (SOD-123) Central Semiconductor CMHD2003 (when used) D4 1 5.6V, 0.5W zener diode (SOD-123) Diodes Inc. BZT52C5V6 D5 1 18V, 0.5W zener diode (SOD-123) Diodes Inc. BZT52C18 D6 1 75V, 250mA high-speed diode (SOT23) Central Semiconductor CMPD914 D7 0 Not installed; 14V, 250mW zener diode (SOD-323) Central Semiconductor CMDZ5244B (when used) 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 (8-pin SO) International Rectifier IRF7464 R1 1 22.6kΩ ±1% resistor (0603) R2 1 2.49kΩ ±1% resistor (0603) R3 1 1MΩ ±1% resistor (0805) R4 1 42.2kΩ 1% resistor (0805) R5 1 0.170Ω ±1% power resistor (1206) Dale-Vishay WSL-12060.170Ω ±1% R6 1 33kΩ ±5% resistor (1206) R7, R12 2 1.2kΩ ±5% resistors (1206) R8 0 Not installed R9 1 14.3kΩ ±1% resistor (0603) R10 1 0Ω ±5% resistor (0805) R11 1 100Ω ±5% resistor (0603) _______________________________________________________________________________________ MAX5052A Evaluation Kit DESIGNATION QTY DESCRIPTION T1 1 35µH, 10W transformer (10-pin Gull Wing) Cooper-Coiltronics CTX03-16034 MAX5052AEUA (8-pin µMAX) U1 1 None 1 Shunt (JU1) None 1 MAX5052A PC board Quick Start The MAX5052A 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 pad and SGND. 2) Connect a second voltmeter to the VOUT2 pad and SGND. 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 a +36V to +72V power supply to the +VIN pad. Do not exceed 100V input voltage. 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 UVLO section. Detailed Description The MAX5052A EV kit is a 9W, isolated flyback DC-to-DC converter that provides +5V and +15V outputs. 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 +36VDC to +72VDC or a -36VDC to -72VDC source. The user must supply at least 22µF 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-to-DC converter achieves up to 83% efficiency. The single-transistor topology and primaryside regulation provide for a low-cost design by eliminating the need for an optocoupler and shunt reference on the secondary side. The MAX5052 EV kit provides cycle-by-cycle, primary-side current-limit protection. The current-sense resistor, R5, senses the current through the transformer’s (T1) primary winding. Switching transistor (N1) turns off when the trip level of 291mV is reached. The surface-mount transformer provides galvanic isolation up to 1500V for both outputs. The MAX5052A EV kit features PC board pads for an RCD snubber network (R8, C10, D3) to minimize leakage-energy ringing and to 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, R2, rectifier D6, and the T1 tertiary winding provides ±5% regulation for the outputs. R7 and R12 are adjusted to preload the tertiary winding for the +5V ±5% output regulation. UVLO provides controlled turn-on and shutdown during brownouts when powering up or powering down. The UVLO settings can be changed by replacing R4. Startup resistor R6 and reservoir capacitor C16 enable the MAX5052A to start up within approximately 500ms. The digital soft-start allows the output voltage to slowly ramp up in a controlled manner within 60ms. The MAX5052A controller switches at a fixed 262kHz frequency and the duty cycle is varied to control energy transfer to the isolated outputs. The maximum duty cycle is 50% for the MAX5052A EV kit’s discontinuous currentmode flyback design. _______________________________________________________________________________________ 3 Evaluates: MAX5052A Component List (continued) Evaluates: MAX5052A MAX5052A Evaluation Kit Table 1. Jumper JU1 Shutdown Mode SHUNT LOCATION MAX5052A UVLO/EN Pin MAX5052A OUTPUT None UVLO resistors R3 and R4 determine startup voltage MAX5052A enabled: VOUT1 = +5V VOUT2 = +15V Installed Pulled low to -VIN Shutdown mode Shutdown Mode and Remote-Control Method The MAX5052A EV kit features two methods to shut down the flyback DC-to-DC converter. Jumper JU1 can be used to shut down the flyback DC-to-DC converter. An alternate method, remote control shutdown, can be achieved with a user-supplied open collector/drain transistor or relay contact connected to the SHDN and -VIN pads of the MAX5052A EV kit. Table 1 lists the shutdown mode. Evaluating Other Output Voltages, Current Limits, and UVLO VOUT1 and VOUT2 Output Voltages The MAX5052A EV kit’s outputs, VOUT1 and VOUT2, are set to +5V and +15V, respectively, by transformer T1’s tertiary turns. The transformer’s respective secondary-output turns, and the resistor-dividers R1 and R2 set the output voltages. 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). R2 is typically chosen to be less than 5kΩ. When evaluating other output voltages, verify that the secondary outputs’ components affected by increased voltage are rated appropriately. Components D1, C3, C4, C13, and D4 of VOUT1 and components D2, C5, C15, and D5 should have their respective voltage rating evaluated. Using the desired scaled-output voltages, calculate R1 using the following equation: NT ( VOUT1 − VVD1 ) × N1 − VVD6 − 1 × R2 R1 = VFB where VOUT1 is the +5V output, NT is the transformer’s tertiary turns = 15, N1 is the transformer’s secondary 4 VOUT1 number of turns = 6, VFB is the MAX5052A reference voltage = 1.23V, VVD6 is the circuit’s tertiary-winding high-speed diode (D6) forward-voltage drop = 1.0V, VVD1 is the circuit’s secondary-side Schottky diode (D1) forward-voltage drop of 0.45V (typ). Both output voltages are 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. Current Limiting The MAX5052A EV kit features current limiting for the transformer’s primary current. The MAX5052A IC turns off switching MOSFET N1 when the voltage at the MAX5052A CS pin reaches 291mV. Current-sense resistor R5 (0.170Ω) limits the transformer peak-primary current to 1.71A (291mV/0.170Ω = 1.71A). This limits the average short-circuit current on the secondary outputs typically to 1.2A (average) and 200mA (average) for VOUT1 and VOUT2, respectively. To evaluate a lower current limit, R5 must be replaced with a different surface-mount resistor (1206 size) as determined by the following equation: R5 = VSENSE IPRIMARY where V SENSE = 291mV and I PRIMARY is the transformer’s maximum primary current. Undervoltage Lockout (UVLO) The MAX5052A EV kit features a UVLO circuit that prevents operation below the programmed input-supply start voltage. R3 and R4 set the voltage at the MAX5052A’s UVLO/EN pin that determines the UVLO wakeup and shutdown levels, 1.28V (typ) and 1.23V (typ), respectively. To evaluate other wakeup and shutdown levels, replace R4 with another surface-mount resistor (0805 size). Refer to the MAX5052/MAX5053 Undervoltage Lockout section in the MAX5052/ MAX5053 data sheet for instructions on selecting R4 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 MAX5052A EV kit and VUVLO = 1.28V (typ). _______________________________________________________________________________________ MAX5052A Evaluation Kit EFFICIENCY vs. OUTPUT CURRENT 100 90 VOUT1 VOUT2 = +15V, 100mA EFFICIENCY (%) 80 70 0V 2V/div 60 VOUT2 VOUT2 = +15V, 25mA 50 40 30 20 0V 5V/div 10 0 0 0.15 0.30 0.45 0.60 0.75 0.90 1.05 1.20 1.35 1.50 10ms/div 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 17.2 VOUT2 = +15V, 25mA 5.4 16.8 5.2 16.4 5.0 VOUT2 (V) VOUT1 (V) 5.6 VOUT2 = +15V, 100mA 4.8 16.0 15.6 4.6 15.2 4.4 14.8 4.2 14.4 4.0 VOUT1 = +5V, 150mA VOUT1 = +5V, 1.5A 14.0 0 0.30 0.60 0.90 1.20 1.50 IOUT1 (A) Figure 3. VOUT1 (+5V) Output Voltage Regulation 0 0.02 0.04 0.06 0.08 0.10 IOUT2 (A) Figure 4. VOUT2 (+15V) Output Voltage Regulation _______________________________________________________________________________________ 5 Evaluates: MAX5052A Flyback Converter Waveforms Evaluates: MAX5052A MAX5052A Evaluation Kit IN FB_P +VIN R6 33kΩ C16 15µF 35V L2 D6 D8 R7 1.2kΩ C12 0.22µF R12 1.2kΩ D7 OPEN 4 FB_P C2 1µF 100V R1 22.6kΩ 1% R2 2.49kΩ 1% 2 3 COMP C14 0.022µF R3 1MΩ 1% VIN FB U1 UVLO/EN 6T 6 D3 OPEN 6 R10 0Ω NDRV C15 1µF D5 L1 D1 C3 68µF 6.3V D4 C13 1µF C6 0.0047µF 250VAC N1 4 4 3 2 R11 100Ω C8 OPEN C17 OPEN 7 VCC C7 0.22µF GND 5 R5 0.170Ω 1% JU1 NOTE: MOSFET N1 = IR IRF7464 Figure 5. MAX5052A EV Kit Schematic 6 SGND VOUT1 7 8 6 5 1 CS 7 28T 2 35µH 1 C10 OPEN C11 0.22µF MAX5052A 1 SHDN 12T C5 47µF 25V 8 C9 2200pF +VIN R4 42.2kΩ 1% R8 OPEN IN R9 14.3kΩ 1% VOUT2 D2 8 3 C1 1µF 100V 9 10 15T +VIN -VIN T1 5 _______________________________________________________________________________________ C4 22µF 6.3V SGND MAX5052A Evaluation Kit Evaluates: MAX5052A Figure 6. MAX5052A EV Kit Component Placement Guide—Component Side Figure 7. MAX5052A EV Kit PC Board Layout—Component Side _______________________________________________________________________________________ 7 Evaluates: MAX5052A MAX5052A Evaluation Kit Figure 8. MAX5052A 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. 8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.