| 摘要 |
<p>SWITCHING VOLTAGE REGULATOR WITH LOW RFI NOISE To convert an unregulated input voltage applied across an input and a reference terminal to a regulated output voltage across a load between the reference and an output terminal, a switching transistor is connected in series with an induction coil between the input and the output terminals. A flyback diode is connected between the reference terminal and the juncture between the transistor and the first coil, and is poled to be reverse biased when the transistor is conductive. The transistor is cyclically (a) switched from full conduction to cutoff to interrupt a current flow between the input and the output terminals and through the coil to induce a voltage across the coil to establish a current flow between the reference and the output terminals and through the diode, (b) switched from cutoff to partial conduction at a controlled rate to reduce the current flow through the diode at a relatively slow, controlled rate, and (c) rapidly switched from partial conduction to full conduction when the current flow through the diode has been reduced to a predetermined value. The gradual reduction of current flow through the diode reduces "snap off" of the diode and minimizes RFI (radio frequency interference) noise generated thereby, and the value of the regulated output voltage is controlled by the duty cycle of the transistor.</p> |
