Efore Oyj

Ilpo Nisonen

An overload protection circuit for supplying electric power has advantageous applications especially in supplying power to capacitive loads. In prior art circuits, the charging current is lead to the capacitive load through a linearly operating transistor or through a power resistor. Therefore, prior art circuits often involve a risk of exceeding safe operating area of a power transistor, or circuits with a large number of components are needed. The present overload protection circuit has an inductor (L) coupled in series with a switching element (Q). Load current is measured (), and the switching element (Q) is controlled () to supply current to the load via the inductor (L) until a determined current limit is achieved. After achieving the current limit the switching element (Q) is controlled to off-state, during which the freewheeling current of the inductor (L) is lead through a voltage dependent element (Z).

Growing community of inventors

Espoo, Finland

Ilpo Nisonen