Patent ID: 7804339
Filing Date: 2010-09-28
Classification: G06F

Abstract:
1. An interface circuit for a serial bus, the interface circuit comprising: a receiving terminal for receiving an input signal having a first signal level and a second signal level; an output terminal for outputting a first voltage signal; a first switching circuit coupled to the receiving terminal, the output terminal and a grounded terminal, for determining a coupling relationship between the output terminal and the grounded terminal according to difference between the input signal and a grounding voltage provided by the grounded terminal; a voltage source for producing a voltage drop based on a driving voltage to provide a first voltage, the driving voltage driving the serial bus interface circuit; a second switching circuit coupled to the receiving terminal, the first switching circuit, the output terminal and the voltage source, for determining a coupling relationship between the first switching circuit and the voltage source according to difference between the input signal and the first voltage; a first switch coupled between the voltage source and the second switching circuit, for determining a coupling relationship between the voltage source and the second switching circuit according to a first control signal; a second switch coupled to the second switching circuit, for determining a coupling relationship between the driving voltage and the second switching circuit according to a second control signal; and a controlling unit coupled to the output terminal, for generating the first control signal and the second control signal according to the first voltage signal; wherein the first switching circuit eliminates generation of a first current flowing from the voltage source to the grounded terminal when the input signal is at a steady state of the first signal level, and the second switching circuit eliminates the generation of the first current when the input signal is a steady state of the second signal level.