Chilisin's new molded High Efficiency Power Inductors (HEI Series) performance allows the designers to select a smaller component while scarifying little to no power efficiency. In some instances there is even an improvement. In analyzing the performance of the HEI inductors, power efficiency will be performed under two conditions: Standby mode (light load, PFM) and In-Use (heavy load, PWM).
1. Light load, PFM (Pulse Frequency Modulation)
In general smart phones tend to be in power save mode for a longer period of time than in heavy load. Hence addressing the efficiency under light load conditions is critical for battery life. During light load mode, the SMPS uses PFM (pulse frequency modulation) mode for switching. Under light load conditions most of the inductor losses are attributed to the AC losses. Since the current is low, actual losses are due to the switching frequency. Hence it is important for an inductor to have a low Rac and the resultant Higher Quality factor (or the so-called Q value). Designers may also compare Q values of inductors as a reference index of which one would present a lower AC loss at low frequencies (<~1MHz). Q and Rac are inversely proportional (High Q = Low Rac).
As can be seen in Fig.1, Chilisin HEI performed a better Q value and resulted into higher power efficiency in the light load mode, as Fig.2 shown.
2. Heavy Load, PWM (Pulse Width Modulation)
Under heavy load, both of DC copper loss, AC copper losses and core loss all are important in the efficiency improvement. Especially, the DCR of the inductor plays a major role in the inductor losses (P=I2RDCR) since the current is significantly higher than in light load.
One of the Chilisin core technologies is to have their own proprietary metal powder formulation for HEI inductors which share the benefits of low RDCR and Rac combinations. In additional to lower DC resistance values, the powders used also exhibits higher Q value, and therefore reduced the core loss further.
Company Website: http://www.chilisin.com.tw/
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