USERS MANUAL ISL8240MEVAL4Z AN1922 Rev 3.00 Dual 20A/Optional 40A Cascadable Evaluation Board Setup Procedure September 29, 2015 The ISL8240MEVAL4Z is a complete, dual step-down switching Recommended Equipment mode DC/DC module. The dual outputs can easily be paralleled for single-output, high current use. It is easy to apply 0V to 20V power supply with at least 5A source current this high power, current sharing DC/DC power module to capability power hungry datacom, telecom and FPGA applications. All Electronic load capable of sinking current up to 40A that is needed in order to have a complete, dual 20A design Digital Multimeters (DMMs) ready for use are the ISL8240M, a few passive components and V setting resistors. 100MHz quad-trace oscilloscope OUT The simplicity of the ISL8240M is its off-the-shelf, unassisted Quick Start implementation. Patented current sharing in multi phase operation greatly reduces ripple currents, BOM costs and For dual output operation, the inputs are BA7 (VIN1), BA8 complexity. The ISL8240M has a thermally enhanced, compact (GND), BA3 (VIN2) and BA4 (GND). The outputs are BA5 17mmx17mmx7.5mm QFN package that operates at full load (VOUT1), BA6 (GND), BA1 (VOUT2) and BA2 (GND). and over-temperature. Easy access to all pins, with few external For paralleled single output operation, the inputs are BA7 components, reduces PCB design to a component layer and a (VIN1) and BA8 (GND). The outputs are BA5 (VOUT1) and BA6 simple ground layer. (GND) with BA5 and BA1 shorted. This ISL8240MEVAL4Z evaluation board is designed for dual 20A output applications. Optionally, this board can easily be converted Ordering Information for 40A single output use. Multiple ISL8240MEVAL4Z boards can PART NUMBER DESCRIPTION be cascadable through the SYNC and CLKOUT pins to operate with phase shifting, for paralleling or multiple output use. The ISL8240MEVAL4Z Evaluation Board input voltage of this board is 4.5V to 20V and the default outputs on this board are set at 1.0V and 1.5V. References ISL8240M datasheet. - LOAD2 V V OUT2 (0A~20A) + 4.5V TO 20V + LOAD1 V V (0A~20A) OUT1 - - V V IN + FIGURE 1. ISL8240MEVAL4Z BOARD IMAGE AN1922 Rev 3.00 Page 1 of 10 September 29, 2015 + -ISL8240MEVAL4Z 4. Connect an electronic load or the device to be powered to the Dual Output Mode outputs BA5 (VOUT1) and BA6 (GND) of the board. All 1. Connect a power supply capable of sourcing at least 5A to connections, especially the low voltage, high current V OUT inputs BA7 (VIN1), BA8 (GND), BA3 (VIN2) and BA4 (GND) of lines, should be able to carry the desired load current and the ISL8240MEVAL4Z evaluation board, with a voltage should be made as short as possible. between 4.5V to 20V. VIN1 and VIN2 can be different with R 18 5. Make sure the setup is connected correctly prior to applying any and R open. 19 power to the board. Adjust the power supply to 12V and turn on 2. Connect an electronic load or device to be powered to the the input power supply. If the board is working properly, the green outputs BA5 (VOUT1), BA6 (GND), BA1 (VOUT2) and BA2 LED will illuminate if not, the red LED will illuminate (recheck the (GND) of the board. All connections, especially the low wire/jumper connections in this case). Measure the output lines, should be able to carry the voltage, high current V OUT voltages, V , which should be at 1.0V. OUT1 desired load current and should be made as short as possible 6. Apply any load that is less than 40A for normal steady state 3. Make sure that the setup is connected correctly. Turn on the operation. Refer to Table 1 to change the output voltage by power supply. If the board is working properly, the green LED changing resistor R . 2 will illuminate if not, the red LED will illuminate (recheck the wire/jumper connections in this case). Measure the output TABLE 2. BOARD CONFIGURATION FOR SINGLE OUTPUT 40A , which should be at 1.0V and V , which voltages, V OUT1 OUT2 APPLICATION should be at 1.5V ENC VMON MODE COMP R9 R13 R14 4. If different output voltages are desired, board resistors can be exchanged to provide the desired V . Please refer to Table 1 OUT Dual OPEN OPEN OPEN OPEN 0 0 OPEN for R /R resistor values, which can be used to produce 2 4 different output voltages. Single ON ON ON ON OPEN OPEN 0 The switching frequency is set to 500kHz by default. The For optimized performance of a 2-phase single output switching frequency can be adjusted, as recommended in application of the ISL8240M, please refer to application note Table 1. By changing the resistor R , the desired frequency FSET AN1923. can be adjusted. If the output voltage is set to 1.5V, the output current will need to be derated at certain conditions to allow for Optional Cascadable Mode safe operation. Please refer to the ISL8240M datasheet. Cascadable mode is needed when multiple evaluation boards TABLE 1. VALUE OF BOTTOM RESISTOR (TOP RESISTOR R , are used for paralleling or multiple output use. Follow the steps 1 R =1k ) AND FREQUENCY SELECTION FOR DIFFERENT shown below: 3 OUTPUT VOLTAGES 1. In order to generate CLKOUT at a shifted phase clock signal, V R /R FREQUENCY R (k ) the control loop of VOUT2 needs to be disabled by connecting OUT 2 4 FSET (V) ( ) (kHz) (V = 12V) IN VSEN2- to VCC. 1.0 1500 500 237 2. Program MODE and VSEN2+ pin voltages to set the CLKOUT signal and the shifted degrees between two phases on the 1.2 1000 550 174 board (refer to Table 3 on page 4). 1.5 665 600 140 3. Use a coaxial cable to connect CLKOUT (J5) to SYNC (J2) of the next evaluation board, which can be programmed for parallel 1.8 499 650 115 or dual output use. 2.5 316 700 100 4. If the second board is programmed for parallel use, the ISHARE pins of the first and second boards need to be tied Optional Paralleled Single Output Mode together. Using two twisted wires, short two different jumpers of JP7 (ISHARE/SGND) on two evaluation boards. Add 1nF 1. To set up the parallel mode, short JP1 (ENC), JP2 (VMON) and capacitors of C for different boards to decouple the noise. JP3 (COMP) with a jumper. To set up 180 interleaving phase 14 between 2 channels, short the MODE pin and GND pin of JP6 5. If the third board is used in cascadable mode, the second with a jumper. board can only be used in the parallel mode to generate the CLKOUT signal for the SYNC pin on the third board. 2. Remove R and R . Change R to 0. Change R and R 9 13 14 18 19 to 0 . Short VOUT1 to VOUT2 using short wires or copper 6. Follow the instructions from Steps 1 through 5 for more straps. Add C for a 470pF capacitor. cascadable boards. 2 3. Connect a power supply capable of sourcing at least 5A to the inputs BA7 (VIN1), BA8 (GND), BA3 (VIN2) and BA4 (GND) of the ISL8240MEVAL4Z evaluation board, with a voltage between 4.5V to 20V. VIN1 and VIN2 need to be shorted together. AN1922 Rev 3.00 Page 2 of 10 September 29, 2015