Voltage supply for proximity switches

摘要

An electronic proximity switch exhibits at the output an electronic switch (T1) switching a load (L). A voltage regulator (2) supplies a regulated voltage (Up) via a storage capacitor (C1). When the electronic switch (T1) is switched through, there is no unregulated supply voltage present at the voltage regulator (2) and the storage capacitor (C1) discharges via the connected proximity indicator (1). The decreasing voltage is compared with a reference voltage (Uref) via a comparator (K1) and when it drops below the reference voltage, the output of the electronic switch (T1) and a further switch (T3) are opened so that the voltage regulator (2) is connected to a voltage and rapidly charges the storage capacitor (C1) via a low-impedance branch. <IMAGE>