USERS MANUAL ISL8240MEVAL3Z AN1923 Rev 1.00 40A, Single Output Evaluation Board Setup Procedure January 28, 2016 Description Board Features The ISL8240M is a complete, dual step-down switching mode Small, compact, and simple design DC/DC module. The dual outputs can easily be paralleled for Connectors, test points, and jumpers for easy probing single-output, high-current use. It is easy to apply this high-power, current-sharing DC/DC power module to Specifications power-hungry datacom, telecom, and FPGA applications. All that is needed in order to have a complete, 40A design ready This evaluation board is designed to operate at the following for use are the ISL8240M, a few passive components, and operating conditions: V setting resistors. OUT Input voltage range from 4.5V to 20V The ease of use virtually eliminates design and manufacturing Resistor programmable output voltage range from 0.6V to risks while dramatically improving time to market. 2.5V (default 1.0V) The simplicity of the ISL8240M is its off-the-shelf, unassisted 20A output current if V is below 1.5V (output current may OUT implementation. Patented module structure allows for higher need to be derated for certain conditions if V is 1.5V or OUT power density and better efficiency than competing solutions. above 1.5V) Patented current sharing in multi-phase operation greatly Switching frequency range from 350kHz to 700kHz (500kHz reduces ripple currents, BOM costs, and complexity. by default) The ISL8240MEVAL3Z evaluation board enables a single Operating temperature range: -40C to +85C output by paralleling two phases to deliver 40A continuous load current. To evaluate the dual output configuration of the Recommended Equipment ISL8240M, please refer to application note AN1922, ISL8240MEVAL4Z Dual 20A/Optional 40A 0V to 20V power supply with at least 10A source current Cascadable Evaluation Board Setup Procedure. The capability ISL8240M supports input voltage from 4.5V to 20V and the Electronic load capable of sinking current up to 40A output voltage ranges from 0.6V to 2.5V. With the single Digital Multimeters (DMMs) resistor modification, the output voltage can be easily adjusted to different voltages. 100MHz quad-trace oscilloscope Related Resources ISL8240M datasheet. LOAD (0A~40A) + + V 4.5V TO 20V IN V + - - V V OUT - FIGURE 1. ISL8240MEVAL3Z BOARD IMAGE AN1923 Rev 1.00 Page 1 of 8 January 28, 2016ISL8240MEVAL3Z This evaluation board is designed for running 40A, 1.0V at room Quick Start temperature without additional cooling systems needed. The inputs are J1 (VIN) and J2 (GND). The outputs are J3 (VOUT) However, if the output voltage is increased or the board is and J4 (GND). Refer to Figure 1 for connections. operated at elevated temperatures, then the available current needs to be derated. Refer to the current derating curves in the 1. Connect a power supply capable of sourcing at least 10A to ISL8240M datasheet to determine the output current available. the input J1 (VIN) and J2 (GND) of the ISL8240MEVAL3Z evaluation board, with a voltage between 4.5V to 20V. For layout of designs using the ISL8240M, the thermal Connect an electronic load or the device to be powered to the performance can be improved by adhering to the following output J3 (VOUT) and J4 (GND) of the board. All connections, design tips: especially the low voltage, high current V lines, should be OUT 1. Use the top and bottom layers to carry the large current. able to carry the desired load current and should be made as VOUT1, VOUT2, Phase 1, Phase 2, PGND, VIN1 and VIN2 short as possible. should have large, solid planes. Place enough thermal vias to 2. Turn on the power supply. Measure the output voltage, V , OUT connect the power planes in different layers under and which should be at 1.0V if the board is working properly. around the module. 3. The ISL8240MEVAL3Z is manufactured with a default V OUT 2. Phase 1 and Phase 2 pads are switching nodes that generate value of 1.0V if different output voltages are desired, board switching noise. Keep these pads under the module. For . Please resistors can be changed to provide the desired V OUT noise-sensitive applications, it is recommended to keep refer to the table printed on the backside of the evaluation phase pads only on the top and inner layers of the PCB do not board or Table 1 for R resistor values, which can be used VSET place phase pads exposed to the outside on the bottom layer to produce different output voltages of the PCB. To improve the thermal performance, the phase The switching frequency is set to 500kHz by default. For V OUT pads can be extended in the inner layer, as shown in Phase 1 higher than 1.0V, the switching frequency will need to be and 8) for and Phase 2 pads on layers 4 and 5 (see Figures 7 . If the output voltage is set to 1.5V adjusted as shown in Table 1 this 40A evaluation board. Make sure that layers 3 and 6 have or higher than 1.5V, the output current will need to be derated to the GND layers to cover the extended areas of phase pads on allow for safe operation at elevated ambient temperatures. layers 4 and 5 to avoid noise coupling. datasheet. Please refer to the derating curves in the ISL8240M 3. To avoid noise coupling, we recommend adding 470pF For V <5.5V, please tie VIN directly to VCC for best efficiency. capacitors on all COMP pins of each module for multiple IN module operations. Also, it is preferred that the EN/FF voltage be higher than 1.5V in order to achieve better stability. 4. If the ambient temperature is high or the board space is limited, airflow is needed to dissipate more heat from the TABLE 1. RESISTANCE SETTING FOR DIFFERENT OUTPUT VOLTAGES modules. A heat sink can also be applied to the top side of the AND OPERATING FREQUENCY (R = 1k) 3 module to further improve the thermal performance (heat V R FREQUENCY R sink recommendation: Aavid Thermalloy, part number OUT VSET FSET (V) ( ) (kHz) (k ) ). 375424B00034G, www.aavid.com 1.0 Default (1500) Default (500) Default (237) 1.2 1000 550 174 1.5 665 600 140 1.8 499 650 115 2.5 316 700 100 Evaluation Board Information The evaluation board size is 3 inchx3 inch. It is a 6-layer board, containing 2-ounce copper on the top and bottom layers and 1-ounce copper on all internal layers. The board can be used as a 40A reference design, refer to Layout on page 4. The board is made up of FR4 material and all components, including the solder attachment, are lead-free. Thermal Considerations and Current Derating For high current applications, board layout is very critical in order to make the module operate safely and deliver maximum allowable power. To carry large currents, the board layout needs to be carefully designed to maximize thermal performance. To achieve this, select enough trace width, copper weight and the proper connectors. AN1923 Rev 1.00 Page 2 of 8 January 28, 2016