Patent ID: 9128500
Filing Date: 2015-09-08
Classification: G05F,H02M,H03K

Abstract:
1. A switching circuit comprising: a switching transistor adapted to control operation of the switching circuit according to a control signal applied to a control terminal of the switching transistor, wherein the switching transistor is a MOSFET and the control terminal comprises the gate of the MOSFET; a regulating circuit connected to the gate of the switching transistor and having a high-side transistor and a low-side transistor and adapted to generate the control signal; and a valley detecting circuit adapted to sense a voltage at the control terminal when the switching transistor is in an OFF state and to generate a drive signal according to the sensed voltage, wherein the regulating circuit is adapted to generate the control signal based on the generated drive signal; wherein the valley detecting circuit includes a comparator having a first input connected to the control terminal of the switching transistor and a second input connected to a reference voltage and wherein the valley detecting circuit is adapted to generate the drive signal based on a comparison of the sensed voltage at the first input of the comparator with the reference voltage at the second input of the comparator when the switching transistor is in the OFF state; wherein the reference voltage is a value within the range of about −0.5 volts to about 0.5 volts; and wherein the valley detecting circuit comprises a resistor connected in series with the low side transistor of the regulating circuit and a diode connected in parallel with the resistor.