Optocoupler having normally-on driving element
AssigneeSharp Kabushiki Kaisha
InventorKazuya Uekawa
Life of this patent
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Abstract
An optocoupler having a driving traic and at least one normally-on driving element couple in series to the driving triac. A light emitting element turns on the driving triac at a time when a phase of a load current is at about 0°. The normally-on driving element is composed of either a MOSFET, or optionally a relay, and an associated element for turning off MOSFET, or relay, at a time when a phase of the load current is about 90°. The arrangement prevents an inrush current or commutation failure, and provides an optocoupler which can be turned off with prescribed timing. Alternative embodiments are disclosed for an optocoupler that can turn itself off when an abnormality occurs, for example, when an ambient temperature rises to an extremely high level.
Claims11
An optocoupler, comprising:
- a driving triac;
- at least one normally-on driving element coupled to an output of the driving triac;
- a load coupled to the driving triac and the normally-on driving element;
- a light emitting element for receiving a first input current for turning on the driving triac and a light receiving element for turning on the driving triac based on an output from the light emitting element so as to supply the load with a load current for driving the load;
- and
- means for turning off the normally-on driving element;
- wherein
- the first input current is applied to the light emitting element at a time when a phase of the load current is substantially at 0°;
- and
- a second input current is applied to the normally-on driving element at a time when a phase of the load current is substantially at 90°.
Dependencies are inferred from the claim text.