Patent ID: 8115536
Filing Date: 2012-02-14
Classification: H02M,H05B,Y02B

Abstract:
1. Self-oscillating switch circuit for use in a switching DC-DC converter, the self-oscillating switch circuit comprising: an output terminal (Tout a high-power input terminal (S a low-power input terminal (S a power switch semi-conductor device (Q a control semi-conductor device (Q a sensing circuit coupled to the control semi-conductor device for generating a sensing voltage, the control semi-conductor device being configured to switch the power switch semi-conductor device non-conductive when the sensing voltage has a predetermined control voltage level; wherein the sensing circuit comprises a first sensing resistor (R 1 A) and a second sensing resistor (R 1 B) for generating the sensing voltage, the sensing circuit being configured such that: the sensing voltage has the predetermined control voltage level, when power is supplied to the high-power input terminal and the load current has a predetermined first peak current level, the first peak current level corresponding to the first power; the sensing voltage has the predetermined control voltage level, when power is supplied to the low-power input terminal and the load current has a predetermined second peak current level, the second peak current level corresponding to the second power.