BASE DRIVE CIRCUIT WITH CONTROLLED dIdt FOR SWITCHING APPLICATIONS
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-08
A control circuit is disclosed which provides high base drive and control dIdt by using a combination of resistors which slows the transition rate. The circuit eliminates the feedback capacitor and employs a basic RC (resistor-capacitor) time constant approach to limit the output transistor current. Different technologies have used various schemes to control dVdt and dIdt of a 1 V/ns general-purpose circuit. In some instances a feedback capacitor is used or a feedback pair of transistors. This circuit uses a resistor combination which has both a better control of dIdt as well as a tighter tolerance. It provides a higher base drive with practically no change in dIdt. Fig. 1 shows a schematic of the circuit with the resistors shown with their specific values indicated. This circuit can provide a dIdt as low as 7.