Inductor selection plays a critical role in the performance of the DRV2700 device. The range of recommended inductances is from 3.3 to 22 µH. In general, higher inductances within a given manufacturer’s inductor series have lower saturation current-limits and lower inductances have higher saturation current-limits. When a larger inductance is selected, the DRV2700 boost converter automatically runs at a lower switching frequency and incurs less switching losses. However, larger values of inductance may have higher ESR which increases the parasitic inductor losses. Because lower values of inductance generally have higher saturation currents, inductors with a lower value are a better choice when attempting to maximize the output current of the boost converter.

Another factor to consider for transformers is the winding ratio. In general, if a 200-V output is desired then, because the SW node can boost up to 100 V, a transformer of 1:2 (100 V:200 V) is the minimum required winding. However, selecting a slightly higher winding ratio to ensure that the 100 V on the primary side is not surpassed while trying to boost up to the desired voltage is good design practice.

For this design example, select an inductor of 3.3 µH with a saturation current of 1.5 A.