Issue link: https://resources.mouser.com/i/1505196
14 \ VISHAY Industry 4.0 and Beyond Higher frequencies allow for the IHLP-7575's lower profile, and thus a higher power density. The trade-off is slightly lower efficiency compared to the usage of a higher profile (10mm) device with lower frequency (Figure 3). The graph in Figure 4 shows the temperature increase of the individual components in the circuit. To support engineers with the prediction of losses during the design phase, Vishay offers a powerful inductor loss calculator tool: https://www.vishay.com/inductors/ calculator/calculator/ Table 1 compares the experimental results with the simulation of the core loss calculator for a 500kHz, 1.5µH IHLP-7575GZ inductor. Interpretation In Table 1, there are three important values for each output power rating: total losses during the testing of the converter; measured efficiency; and values given by Vishay's online core loss calculator, which are very conservative with a high safety margin of about 50%. As shown in the table, these losses would result in a temperature rise of up to 80°C, which cannot be observed during the evaluation. Vishay offers more precise magnetic simulation software in its R&D location. Output power Output current Efficiency measured Total losses measured Inductor temperature rise (measured) Core loss calculator (online simulation) Temperature rise (simulation) Total inductor losses (lab simulation) 100W 8.3A 94.4% 5.4W 15°C 6.2W 62°C 3.15W 200W 16.7A 96.6% 6.8W 22°C 6.6W 66°C 3.5W 250W 20.8A 96.6% 8.5W 26°C 6.9W 69°C 3.8W 300W 25A 96.5% 10.5W 30°C 7.2W 72°C 4.3W 400W 33.3A 96% 16W 40°C 8.1W 80°C 5.4W Table 1: Experimental data according to Figure 3 and Figure 4 compared to results from Vishay´s core loss calculator Figure 3: A higher frequency of 500kHz allows for the usage of a smaller inductor with a 7mm height to achieve higher power density. The drawback is slightly reduced system efficiency compared to larger inductor at a lower frequency (Source: Vishay) Figure 4: Temperature rise of a high electron mobilility transistor (HEMT) and inductors vs. the output power of the converter (BSC = bottom-side cooling only; DSC = dual-side cooling) (Source: Vishay) Efficiency The reference design shows peak efficiency of ~97% for 48V to 12V conversion using Vishay's IHLP-7575GZ power inductor at 500kHz or the IHLP-7575JZ at 300kHz.