Detection output circuit for a photoelectric switch integrated circuit with reduced interconnections

摘要

A photoelectric switch is adapted for use as either a transmission type or a reflection type switch. To provide an integrated circuit for the photoelectric switch and to minimize input/output pins, multiple functions are assigned to each input/output pin. Such functions are provided via first to fourth integrated circuit input/output pins, i.e., the first pin serves functions in the supply of a detection output and a self-diagnosing output; the second pin supports a circuit for driving a projection type LED and a circuit for turning the LED off; the third pin supports a circuit for reversing a stable indication output and an operation indicating output; and the fourth pin supports a circuit for amplifying a received photo-signal and for controlling the mode of combination of photoelectric signals from a pair of photo-diodes. The photoelectric switch includes a support circuit external of the integrated circuit for supporting the various functions provided via the first to fourth pins and two additional pins used in providing operating power.