Opto-coupler protection circuit maintaining galvanic separation - uses damped series oscillation circuit in parallel with opto-coupler

摘要

The protection circuit for an opto-coupler incorporated in an electronic power stage provides increased common node transient immunity. The reference potential (B1) for the control line (W1) on the primary side of the opto-coupler (U1) is combined with the reference potential (B2) on the output side in a damped series resonance circuit containing a capacitor (C1), a damping resistance (R3) and an oscillation coil (L1). Pref. the current strength of the primary control pulses supplied to the reference potential terminal (B2) on the output side of the opto-coupler (U1) via the resonance circuit is less than one tenth of the current flowing in the power stage. The oscillation coil (L1) may be integrated in the control line (W1). ADVANTAGE - Maintains galvanic separation between prim. and sec. sides. Increases resistance to interference w.r.t. differential loading.