Both Signal Transformer and DigiKey application engineers key on a few primary attributes when providing assistance in determining the right SMD inductor solution. The first is the inductance value, the main functional parameter of an inductor. It is the property of an inductor where a change in the electric current induces a counter electromotive force which opposes that current change. The unit of measure for the inductance is the Henry, abbreviated “H”. The inductance in H is the calculated value by design which determines the inductors capability to handle the desired power and control of current. The purpose of the inductance is to establish a sufficient energy storage amount and ensure adequate reduction in ripple current for proper filtering. The inductance is specified as an “open circuit nominal value”. The inductance is measure typically at 0.25V and 100kHz, however each data sheet clearly posts the relative voltage and frequency for the specified test condition.