| 摘要 |
A circuit arrangement (1) comprises a current source (10), a comparator (50) and a control device (90). The current source (10) serves for supplying a light-emitting diode (41). The comparator (50) may be coupled to the light-emitting diode (41) at a first input (51) via a push-button (101). The comparator (50) may be fed with a reference voltage (VREF) at a second terminal (52). The control device (90) selectively puts the current source (10) into a first operational state (A) for polling a push-button position of the push-button (101) or into a second operational state (B) for emitting radiation by means of the light-emitting diode (41). |
