Switching Regulator With No Choke
Original Publication Date: 1983-Nov-01
Included in the Prior Art Database: 2005-Feb-07
A preregulation circuit is disclosed. The circuit provides a coarse preregulation voltage output of a relatively small voltage within a specified range for use in logic circuits. It also provides a larger output voltage for driving a main load such as a stepping motor. Preregulation is achieved without the bulk of conventional switching regulator or the inefficiency of a series regulator. Basic operation of the circuit shown in Fig. 1 is that the pass transistor Q2 is turned off when the input voltage is above a preset level. Transistor Q1 drives transistor Q2 to charge capacitor C2 until voltage Vin minus voltage Vref is equal to Vp of transistor Q1 . At this point Q1 is cut off, switching Q2 off and preventing any additional charging of C2 until voltage Vin drops back down. As shown in Fig.