19-6021 Rev 0 9/11 MAX13256 Evaluation Kit Evaluates: MAX13256 General Description Features The MAX13256 evaluation kit (EV kit) is a fully assembled S 8V to 36V Input Supply Range and tested PCB that contains the MAX13256 10W iso- S Up to 90% Efficiency lated H-bridge DC-DC converter. The EV kit operates S Full-Wave Rectified Output from an 8V to 36V DC power source and the on-board 1:1 turns-ratio transformer from HALO sets the output voltage S Configurable for a Voltage Doubler, Bipolar range from 6.8V to 34.8V with a 300mA current limit. Half-Wave Rectifier, and Push-Pull Rectifier Outputs The EV kit provides greater than 90% overall effi- S Internal or External Clock Operation Option ciency at +24V between 2.2W and up to 8.3W output S Designed for 1500V Isolation RMS power using an H-bridge DC-DC converter topology. Input-ripple current and radiated noise are minimized S Proven PCB Layout by the inherent balanced nature of the design with S Fully Assembled and Tested no interruption in the input current. Undervoltage lockout (UVLO), adjustable current limit, and thermal shutdown provide for a robust 10W isolated supply. The surface-mount transformer provides galvanic isolation with the output powered from a full-wave rectifier circuit, reducing the output-voltage ripple. The EV kit circuit is configured as a full-wave rectifier, with an output voltage that follows the input voltage but Ordering Information appears at end of data sheet. is configurable for other topologies including a voltage doubler, bipolar outputs, half-wave rectification, and a push-pull rectifier. Use HALOs TGMR-512V6LF transformer for 4:1 turns-ratio operation providing up to 1A load capability. The device is available in a 10-pin (3mm x 3mm) TDFN package with an exposed pad. Component List DESIGNATION QTY DESCRIPTION DESIGNATION QTY DESCRIPTION R1 1 1FF Q10%, 50V C0G ceramic 1kI Q1% resistor (0603) C1, C4 2 capacitors (0805) R2 1 750I Q5% resistor (0603) Murata GRM21BR71H105K R3 1 49.9kI Q1% resistor (0603) C2, C3, C8 0 Not installed, capacitors (0603) R4 1 10kI Q5% resistor (0603) 0.1FF Q10%, 50V X7R ceramic R5R8 0 Not installed, resistors (0603) C5 1 capacitor (0603) R9, R10 2 0I Q5% resistors (0603) Murata GRM188R71H104K 1:1, 300mA turns transformer 2.2FF Q10%, 16V X7R ceramic T1 1 (6 Gull Wing) C6 1 capacitor (0805) HALO TGMR-511V6LF Murata GRM21BR71C225K H-bridge transformer driver C7 0 Not installed, capacitor (0805) U1 1 (10 TDFN-EP) 40V, 1A Schottky diodes (SMB) Maxim MAX13256ATB+ D1D4 4 Fairchild MBRS140 5V LDO (6 TDFN-EP) D5 1 Red LED (0603) U2 1 Maxim MAX15007BATT+ GND, SGND 2 Black test points 3 Shunts JU1 1 3-pin header PCB: MAX13256 EVALUATION 1 JU2, JU4 2 2-pin headers KIT JU3 1 Not installed, 2-pin header Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com.MAX13256 Evaluation Kit Evaluates: MAX13256 Component Suppliers SUPPLIER PHONE WEBSITE Fairchild Semiconductor 888-522-5372 www.fairchildsemi.com HALO Electronics, Inc. 650-903-3800 www.haloelectronics.com Murata Electronics North America, Inc. 770-436-1300 www.murata-northamerica.com Note: Indicate that you are using the MAX13256 when contacting these component suppliers. The device is an integrated primary-side controller Quick Start and H-bridge driver for isolated power-supply circuits. The device contains an on-board oscillator, protec- Required Equipment tion circuitry, and internal MOSFETs to provide up to MAX13256 EV kit 300mA of current to the transformers primary winding. +24V, 1A DC power supply The device can be operated using the internal 425kHz Electronic load capable of 200mA oscillator, or driven by an external clock to synchronize multiple devices and control EMI behavior. Regardless Ammeter of the clock source being used, an internal flip-flop Voltmeter stage guarantees a fixed 50% duty cycle, preventing DC current flow in the transformer as long as the clocks period is constant. Procedure The device operates from a single-supply voltage and The EV kit is fully assembled and tested. Follow the steps includes UVLO and an active-low enable input for below to verify board operation. Caution: Do not turn on controlled startup. If the input voltage at VDD falls below the power until all connections are completed. 6.3V, or the EN input is pulled above 2V, the device shuts 1) Verify that jumpers JU1, JU2, and JU4 are in their down and ST1 and ST2 are high impedance. default positions, as shown in Tables 1, 2, and 3. The device features an adjustable output current limit 2) Set the DC power supply to 24V. at the transformer driver outputs (ST1 and ST2). When 3) Set the electronic load to 200mA and disable the current reaches the limit for longer than the 1.2ms the output. blanking time, the drive outputs are disabled and 4) Connect the voltmeter between the +VOUT and the FAULT output asserts. The drivers are reenabled after the 38.2ms autoretry time. If a continuous fault SGND PCB pads on the EV kit. condition is present, the duty cycle of the fault current is 5) Connect the ammeter between the +VOUT PCB approximately 3%. pad on the EV kit and the positive terminal on the The EV kit PCB is designed for 1500V isolation, electronic load. The negative terminal on the RMS electronic load is connected to the SGND PCB pad with 300 mil spacing between the GND and SGND planes. The bottom PCB GND plane under device U1 on the EV kit. is utilized as a thermal heatsink for power dissipation 6) Connect the power supply between the VDD and of the devices thermally enhanced TDFN package with GND PCB pads on the EV kit. exposed pad. Test points GND and SGND are provided 7) Turn on the power supply. on the PCB for probing the respective ground planes, or 8) Enable the electronic load. to connect the GND and SGND planes for nonisolated evaluation of the circuit. 9) Verify that the ammeter reads approximately 200mA. Clock Source 10) Verify that the voltmeter reads approximately 22.8V. The device has two modes of operation: internal Detailed Description oscillator or external clock. To use the internal 425kHz oscillator, place a shunt in the 1-2 position on jumper The MAX13256 EV kit is a 10W, isolated H-bridge DC-DC JU2. When using an external clock, remove the shunt converter that provides an unregulated output that is from JU2 and apply a clock signal on the CLK PCB two diode-voltage drops less than its input supply, pad on the EV kit. An internal flip-flop divides the with respect to the isolated ground. In the default external clock by two, generating a switching signal with a configuration, the maximum load is limited by the device guaranteed 50% duty cycle. As a result, the device and the on-board transformer. outputs switch at 1/2 the external clock frequency. Maxim Integrated Products 2