USERS MANUAL ISL8117EVAL2Z UG020 Rev 0.00 Evaluation Board User Guide March 17, 2015 Description Key Features Wide input range: 18V to 60V The ISL8117EVAL2Z evaluation board (shown in Figure 1) High light-load efficiency in pulse skipping DEM operation features the ISL8117. The ISL8117 is a 60V high voltage synchronous buck controller that offers external soft-start, Programmable soft-start independent enable functions and integrates UV/OV/OC/OT Optional DEM/CCM operation protection. Its current mode control architecture and internal compensation network keep peripheral component count Supports prebias output with SR soft-start minimal. Programmable switching frequency ranging from External frequency sync 200kHz to 2MHz helps to optimize inductor size while the PGOOD indicator strong gate driver delivers up to 30A for the buck output. OCP, OVP, OTP, UVP protection Back biased from output to improve efficiency Specifications The ISL8117EVAL2Z evaluation board is designed for high References current applications. The current rating of the ISL8117EVAL2Z ISL8117 Datasheet is limited by the FETs and inductor selected. The ISL8117 gate driver is capable of delivering up to 20A for the buck output as Ordering Information long as the proper FETs and inductor are provided. The electrical ratings of ISL8117EVAL2Z are shown in Table 1. PART NUMBER DESCRIPTION TABLE 1. ELECTRICAL RATING ISL8117EVAL2Z High Voltage PWM Step-down Synchronous Buck Controller Evaluation PARAMETER RATING Board Input Voltage 18V to 60V Switching Frequency 300kHz Output Voltage 12V Output Current 20A OCP Set Point Minimum 25A at ambient room temperature FIGURE 1. ISL8117EVAL2Z TOP SIDE UG020 Rev 0.00 Page 1 of 11 March 17, 2015ISL8117EVAL2Z Recommended Testing Functional Description Equipment The ISL8117EVAL2Z is the same test board used by the Intersil application engineers and IC designers to evaluate the The following materials are recommended to perform testing: performance of the ISL8117 QFN IC. The board is set to provide 0V to 60V power supply with at least 30A source current an easy and complete evaluation of all the IC and board capability functions. Electronic loads capable of sinking current up to 30A As shown in Figure 3 on page 3, 18V to 60V V is supplied to J1 IN Digital Multimeters (DMMs) (+) and J2 (-). The regulated 12V output on J3 (+) and J4 (-) can supply up to 20A to the load. Due to the high thermal efficiency, 100MHz quad-trace oscilloscope the evaluation board can run at 20A continuously without airflow under room temperature ambient conditions. Quick Test Guide 1. Jumper J5 provides the option to select CCM or DEM. Please Test points TP1 through TP19 provide easy access to IC pin and refer to Table 2 for the desired operating option. Ensure that external signal injection terminals. the circuit is correctly connected to the supply and electronic As shown in Table 2, connector J5 provides selection of either for loads prior to applying any power. Please refer to Figure 3 CCM mode (shorting pin 1 and pin 2) or DEM mode (shorting proper set-up. pin 2 and pin 3). Connector J6 provides an option to disable the 2. Turn on the power supply. converter by shorting its pin 1 and 2. 3. Adjust input voltage V within the specified range and IN observe output voltage. The output voltage variation should Operating Range be within 3%. 4. Adjust load current within the specified range and observe The input voltage range is from 18V to 60V for an output voltage output voltage. The output voltage variation should be of 12V. If the output voltage is set to a lower value, the minimum within 3%. V can be reset to a lower value by changing the ratio of R and IN 4 R . The minimum EN threshold that V can be set to is 4.5V. 5 IN 5. Use an oscilloscope to observe output voltage ripple and Phase node ringing. For accurate measurement, please refer The rated load current is 20A with the OCP point set at minimum to Figure 2 for proper test set-up. 25A at room ambient condition. TABLE 2. DESIRED OPERATING OPTIONS The operating temperature range is from -40C to +125C. JUMPER Please note that airflow is needed for higher temperature POSITION FUNCTION ambient conditions. J5 CCM (Pin 1-2) Continuous current mode DEM (Pin 2-3) Diode emulation mode PCB Layout Guideline J6 (Pin 1-2) Disable the PWM Careful attention to layout requirements is necessary for successful implementation of an ISL8117 based DC/DC converter. The ISL8117 switches at a very high frequency and therefore the switching times are very short. At these switching frequencies, even the shortest trace has significant impedance. Also, the peak gate drive current rises significantly in an extremely short time. Transition speed of the current from one device to another causes voltage spikes across the OUTPUT CAP interconnecting impedances and parasitic circuit elements. OR MOSFET These voltage spikes can degrade efficiency, generate EMI, and increase device overvoltage stress and ringing. Careful FIGURE 2. PROPER PROBE SET-UP TO MEASURE OUTPUT RIPPLE component selection and proper PC board layout minimizes the AND PHASE NODE RINGING magnitude of these voltage spikes. There are three sets of critical components in a DC/DC converter using the ISL8117: the controller, the switching power components and the small signal components. The switching power components are the most critical from a layout point of view because they switch a large amount of energy, which tends to generate a large amount of noise. The critical small signal components are those connected to sensitive nodes or those supplying critical bias currents. A multilayer printed circuit board is recommended. UG020 Rev 0.00 Page 2 of 11 March 17, 2015