Switching regulator current supply with voltage regulator - uses threshold voltage switching of control pulse FET switch w.r.t supply level, preventing overshoot

摘要

A switching regulator current supply contg. a voltage regulator with a desired voltage source, e.g. for supplying a low voltage direct current load from an alternating current supply network, eliminates output voltage overshoot without entailing an unacceptably slow voltage rise time. One voltage regulator (IC2) input (ni) is connected to a capacitor (C3) and via one or more resistors (R8, R7, R5) to the desired voltage source connection actuating the regulator. The same input (ni) is also connected via a switch (T1), pref. a field-effect transistor (FET) to a voltage source whose voltage blocks or opens the control pulse channel (ST). A component (IC1) constituting a control element of the switching regulator holds the FET switch (T1) open as long as the current supply input voltage lies below the desired voltage value. The capacitor (C3) charging circuit time constant is larger than that of the discharge circuit.