BIAS VOLTAGE GENERATING CIRCUIT AND SWITCHING POWER SUPPLY THEREOF

摘要

Disclosed herein are bias voltage generating circuits configured for switching power supplies, and associated control methods. In one embodiment, a bias voltage generating circuit can include: (i) a first control circuit configured to compare a drain-source voltage of a switch against a bias voltage; (ii) a capacitor, with the bias voltage across the capacitor; (iii) a second control circuit configured to control the switch, and that is enabled when the bias voltage is at least as high as an expected bias voltage; (iv) the first control circuit being configured to control the capacitor to charge when the drain-source voltage of the switch is greater than the bias voltage; and (v) the bias voltage being less than an overvoltage protection voltage when the capacitor charges, and where the overvoltage protection voltage comprises a voltage that is a predetermined amount higher than the expected bias voltage.

主权项

1. A bias voltage generating circuit, comprising:
a) a first control circuit configured to compare a drain-source voltage of a first switch against a bias voltage across a capacitor; c) a second control circuit configured to control said first switch, wherein said second control circuit is configured to be enabled when said bias voltage is at least as high as an expected bias voltage; d) wherein said first control circuit is configured to control said first capacitor to charge when said drain-source voltage of said first switch is greater than said bias voltage; and e) wherein said bias voltage is less than an overvoltage protection voltage when said capacitor charges, and wherein said overvoltage protection voltage comprises a voltage that is a predetermined amount higher than said expected bias voltage.