USERS MANUAL ISL8117AEVAL1Z UG049.0 Rev 0.00 Evaluation Board User Guide September 3, 2015 Description Key Features Wide input range: 18V to 60V The ISL8117AEVAL1Z evaluation board (shown in Figure 4 on page 4) features the ISL8117A. The ISL8117A is a 60V high High light-load efficiency in pulse skipping DEM operation voltage synchronous buck controller that offers external Programmable soft-start soft-start, independent enable functions and integrates UV/OV/OC/OT protection. Its current mode control architecture Optional DEM/CCM operation and internal compensation network keep peripheral Supports prebias output with SR soft-start component count minimal. Programmable switching frequency ranging from 100kHz to 2MHz helps to optimize External frequency sync inductor size while the strong gate driver delivers up to 30A for PGOOD indicator the buck output. OCP, OVP, OTP, UVP protection Specifications Back biased from output to improve efficiency The ISL8117AEVAL1Z evaluation board is designed for high References current applications. The current rating of the ISL8117A Datasheet ISL8117AEVAL1Z is limited by the FETs and inductor selected. The ISL8117A gate driver is capable of delivering up to 20A for the buck output as long as the proper FETs and inductor are Ordering Information provided. The electrical ratings of the ISL8117AEVAL1Z are PART NUMBER DESCRIPTION shown in Table 1. ISL8117AEVAL1Z High voltage PWM step-down TABLE 1. ELECTRICAL RATING 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 V V IN OUT UGATE LGATE/OCS ISL8117A EXTBIAS ISL80138 MOD/SYNC VCC5C EN DEM DISABLE CCM FIGURE 1. BLOCK DIAGRAM UG049.0 Rev 0.00 Page 1 of 12 September 3, 2015ISL8117AEVAL1Z Recommended Testing Functional Description Equipment The ISL8117AEVAL1Z 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 ISL8117A 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 (+) and J2 (-). The regulated 12V output on J3 (+) and J4 (-) can Digital Multimeters (DMMs) 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 Test points TP1 through TP19 provide easy access to IC pin and external signal injection terminals. 1. Jumper J5 provides the option to select CCM or DEM. Please refer to Table 2 for the desired operating option. Ensure that As shown in Table 2, connector J5 provides selection of either the circuit is correctly connected to the supply and electronic CCM mode (shorting pin 1 and pin 2) or DEM mode (shorting for loads prior to applying any power. Please refer to Figure 3 pin 2 and pin 3). Connector J6 provides an option to disable the proper set-up. converter by shorting its pin 1 and 2. 2. Turn on the power supply. Operating Range 3. Adjust input voltage V within the specified range and IN observe output voltage. The output voltage variation should The input voltage range is from 18V to 60V for an output voltage be within 3%. of 12V. If the output voltage is set to a lower value, the minimum V can be reset to a lower value by changing the ratio of R and 4. Adjust load current within the specified range and observe IN 4 output voltage. The output voltage variation should be R . The minimum EN threshold that V can be set to is 4.5V. 5 IN within 3%. The rated load current is 20A with the OCP point set at minimum 5. Use an oscilloscope to observe output voltage ripple and 25A at room ambient condition. Phase node ringing. For accurate measurement, please refer The operating temperature range is from -40C to +125C. to Figure 2 for proper test set-up. Please note that airflow is needed for higher temperature TABLE 2. DESIRED OPERATING OPTIONS ambient conditions. JUMPER POSITION FUNCTION PCB Layout Guideline J5 CCM (Pin 1-2) Continuous current mode Careful attention to layout requirements is necessary for successful implementation of an ISL8117A based DC/DC DEM (Pin 2-3) Diode emulation mode converter. The ISL8117A switches at a very high frequency and J6 (Pin 1-2) Disable the PWM 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 interconnecting impedances and parasitic circuit elements. These voltage spikes can degrade efficiency, generate EMI, and increase device overvoltage stress and ringing. Careful component selection and proper PC board layout minimizes the OUTPUT CAP magnitude of these voltage spikes. OR MOSFET There are three sets of critical components in a DC/DC converter FIGURE 2. PROPER PROBE SET-UP TO MEASURE OUTPUT RIPPLE using the ISL8117A: AND PHASE NODE RINGING The controller The switching power components 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. UG049.0 Rev 0.00 Page 2 of 12 September 3, 2015