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1 9-0; Rev ; /07 MAX0 Evaluation Kit General Description The MAX0 evaluation kit (EV kit) is a fully assembled and tested printed circuit board (PCB) that contains a 0W forward converter in the industry-standard halfbrick footprint. The circuit is configured for a +.0V output voltage and provides up to 0A of current. Power for the circuit can be provided from either a +6V to +7V or -6V to -7V DC source. High efficiency of 86% is achieved at A using a single transistor, forward converter topology providing output power up to 0W. The surface-mount transformer provides galvanic isolation and has a reset winding to recover magnetic energy. Galvanic isolation up to 00V is achieved by an optocoupler and surfacemount transformer. Operation at 80kHz allows the use of small magnetics and output capacitors. Warning: The MAX0 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. Component Suppliers SUPPLIER PHONE WEBSITE Central Semiconductor Coiltronics Dale/Vishay General Semiconductor/ Vishay Features +6V to +7V or -6V to -7V Input Range +V Output at 0A VOUT Regulation better than 0.% over Line and Load 86% Efficiency at 48V Input and V/A Output Half-Brick Module Footprint and Pinout Short-Circuit Protection 7kHz Switching Frequency Designed for 00V Isolation Soft-Start Fully Assembled and Tested Remote ON/OFF Remote Sense Ordering Information PART TEMP RANGE IC PACKAGE MAX0EVKIT 0 C to +70 C 8 SO MAX0EVKIT+ 0 C to +70 C 8 SO +Denotes a lead-free package and RoHS-compliant EV kit. Component List DESIGNATION QTY DESCRIPTION C, C 0.µF ±0%, 0V X7R ceramic capacitors (080) Taiyo Yuden UMKBJ04KG C 0.0µF ±0%, 0V X7R ceramic capacitor (080) C 0 Not installed (080) C4, C, C6 0.68µF, 00V X7R ceramic capacitors (8) TDK C4X7RA684K International Rectifier Murata Mfg. Co., Ltd. Sanyo North America Corp Taiyo Yuden TDK Corp Note: Indicate that you are using the MAX0 when contacting these component suppliers. C7, C, C4 C8 C9 60µF, 6.V electrolytic capacitors (8 x.) Sanyo 6MV60WX 0.047µF ±0%, 0V X7R ceramic capacitor (080) Taiyo Yuden UMKBJ47KG 0µF ±0%, 6V XR ceramic capacitor (0) Taiyo Yuden EMKBJ06MN Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at , or visit Maxim s website at

2 DESIGNATION QTY DESCRIPTION C0 C C C6 C7 D 0 D 0 D D4 D L N 0.µF ±0%, 6V X7R ceramic capacitor (060) Taiyo Yuden EMK07BJ04KA 0.µF ±0%, V X7R ceramic capacitor (080) Taiyo Yuden GMKBJ4KG 0.00µF, 00V X7R ceramic capacitor (060) Murata GRM9-X7R0K µF, 0VAC X7R ceramic capacitor (0) Murata GADR7GC47KY0L 0.0µF ±0%, V X7R ceramic capacitor (060) Not installed V, 0mW zener diode (S-mini) Not installed V, 0mW zener diode (S-mini) 80V, 00mA Schottky diode (S-mini) 40V, 0A Schottky diode (TO-0AB) General Semiconductor SBL040CT 0V, 0mA high-voltage switching diode (SOD-) Central Semiconductor CMHD00 4.7µH,.A inductor Coiltronics, HC-4R7-R 00V, 8A n-channel MOSFET (TO-0AB) Inter nati onal Recti fi er IRF640N P 6F Component List (continued) DESIGNATION QTY DESCRIPTION R 40kΩ ±% resistor (080) R6 0.Ω ±% power resistor (06) Dale Electronics, Inc. WSL06 R000FEA R7 Ω ±% resistor (080) R8 499Ω ±% resistor (080) R9 0Ω ±% resistor (080) R.kΩ ±% resistor (080) R 8.kΩ ±% resistor (080) R 4.7kΩ ±% resistor (080) R.kΩ ±% resistor (080) R6, R7 Ω ±% resistors (080) T 70µH :0.87: 0.7:0.7 turn transformer (-pin Gull Wing) Coiltronics CTX0-486 U MAX0ESA+ (8-pin SO) U U 70V ±00% to 00% CTR phototransistor (8-pin SO) Fairchild M0C07M.4V precision shunt regulator (SOT) Texas Instruments TLV4AIDBV Aluminum heatsink plate Vista Industrial Products 0 Nylon spacers, /4 x /8 nylon Nylon screws, 4-40 x /4 Nylon screws, 4-40 x / Nylon screws, 6- x /8 TO-0AB Mica thermal insulating pads PCB: MAX0 Evaluation Kit Q 0 Not installed npn transistor (SOT) R, R0 0 Not installed (080) R 0Ω ±% resistor (06)

3 Quick Start The MAX0 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. Output ) Connect a jumper wire from the VOUT pin to the +SENSE pin. ) Connect a jumper wire from the SGND pin to the -SENSE pin. ) Connect a voltmeter to the VOUT pin and SGND. 4) Connect a +6V to +7V power supply to the VIN+ pin. Do not exceed 00V input voltage. Connect the power supply s ground to the VIN- pin. ) Turn on the power supply above +6V and verify that VOUT provides +V at the voltmeter. For instructions on selecting the feedback resistors for other output voltages, refer to the Evaluating other Output Voltages section in this document. Detailed Description The MAX0 EV kit is a 0W forward converter which provides +.0V and up to 0A at the output. The circuit can be powered from a +6V to +7V or a -6V to -7V DC source. The user must supply at least 0µF of bulk storage capacitor at the input terminals (VIN+, VIN-). The capacitor should be rated for 00V and be able to carry.a of ripple current. The 0W forward converter achieves high efficiency by using a single transistor topology. Current limiting protects the converter against short circuits at the output. A current sense resistor (R6) senses the current through the primary of the transformer (T) and the switching transistor (N) and turns off the transistor when the trip level of 00mV is reached. The surfacemount transformer features a reset winding that, along with diode (D), recovers the magnetic energy stored in the core and feeds it back to the input (VIN+). The transformer provides galvanic isolation up to 00V. Shunt regulator (U) along with feedback resistors (R, R) provide voltage feedback to the primary side through optocoupler (U). Remote output voltage sensing is provided by the +SENSE and -SENSE for accurate output voltage regulation across the load. The softstart allows the output voltage to slowly ramp up in a controlled manner within 0ms. The MAX0 controller switches at a fixed 7kHz frequency, and the duty cycle is varied to control energy transfer to the output. Shutdown Shutdown Mode (Remote Control Method) The MAX0 EV kit features a pin to remotely shutdown the forward converter. An open-collector/drain transistor or relay contact must be connected to the SHDN and VIN- pins of the EV kit. Table lists the options. Table. Shutdown Pin Function (Remote Control) SHDN PIN Open Pull low MAX0 OUTPUT MAX0 enabled, V OUT = +.0V Shutdown mode, V OUT = 0V Evaluating Other Output Voltages, Current Limits, and Soft-Starts VOUT Output Voltage The MAX0 EV kit s output (V OUT ) is set to +.0V by feedback resistors (R, R). To generate output voltages other than +.0V (+.V to +.0V), select different voltage-divider resistors (R, R). Resistor R is typically chosen to be less than kω. Using the desired output voltage, resistor R is then found by the following equation: R = [R / ((V OUT / V REF ) - )] where V REF =.4V The maximum output current should be limited to less than 0A. The usable output voltage range for the EV kit is +.V to +.0V. Additionally, ICs U, U, and resistor R9 limit the minimum output voltage (V OUT ) to +.V. Current Limiting The EV kit features current limiting for the transformer primary current. The MAX0 IC turns off the switching MOSFET (N) when the voltage at the CS pin of the device reaches 46mV. A current sense resistor (R6, 0.Ω) limits the peak primary current to 4.6A (46mV / 0.Ω = 4.6A). This will limit short-circuit current on the secondary output (VOUT) to A typically. To evaluate lower current limits, the current sense resistor (R6) must

4 be replaced with a surface-mount resistor (06 size) as determined by the following equation: R6 = VSENSE / ((N S / N P ) x (. x IOUTMAX)) where V SENSE = 0.V, N S =, N P = 4, and I OUTMAX = maximum DC output current (0A as configured). Soft-Start The MAX0 EV kit limits the ramp time to full current limit and duty cycle with a soft-start feature. Capacitor C (0.0µF), sets the ramp time to 0ms. To evaluate other soft-start ramp times replace capacitor C with another surface mount capacitor (080 size) as determined by the following equation: C (µf) = soft-start time (s) / (0.4s/µF) Forward Converter Waveforms V/div 0V 4ms/div Figure. Output Voltage Transient at Power-Up. VIN+ = 48V, I OUT = A EFFICIENCY (%) vs. OUTPUT CURRENT (A) EFFICIENCY (%) V/div 0V OUTPUT CURRENT (A) Figure. Efficiency vs. Output Current. VIN+ = 48V μs/div Figure. MOSFET N, Drain-Source Voltage Waveform, VIN+ = 48V 4

5 VIN+ VIN- C9 0μF VDD R 4.7kΩ % VCC VIN C 0.μF C 0.μF VDD 8 D V+ V CC V DD R VIN D T T Q 4 SHORT COLLECTION TO EMITTER C4 0.68μF U MAX0 OPTO NDRV 7 GND 6 SS/SHDN 6 C 0.68μF CS U 4 C6 0.68μF R7 Ω C 0.0μF C μF SHDN D CS R9 0Ω R6 0.Ω % T 6 4T N, T 8, 9 R8 499Ω % R6 Ω R 0Ω VOUT +SENSE C 0.00μF 00V C μF 0VAC C CS D4 L 4.7μH C7 60μF 6.V C 60μF 6.V C4 60μF 6.V VOUT C 0.μF SGND R.kΩ % R0 SHORT C7 0.0μF D R 40kΩ 7 U C0 0.μF 4 R 8.kΩ % R.kΩ % R7 Ω -SENSE Figure 4. MAX0 EV Kit Schematic

6 .0".0" Figure. MAX0 EV Kit Component Placement Guide Component Side Figure 6. MAX0 EV Kit PCB Layout Component Side.0".0" Figure 7. MAX0 EV Kit PCB Layout Inner Layer, Ground Plane Figure 8. MAX0 EV Kit PCB Layout Inner Layer, Power Plane 6

7 .0".0" Figure 9. MAX0 EV Kit PCB Layout Solder Side Figure 0. MAX0 EV Kit Component Placement Guide Solder Side Revision History Pages changed at Rev :,, 6, 7 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.