Patent ID: 8054107

Claim:
An operational circuit, comprising: a first stage, having a first input terminal for receiving an input signal and a second input terminal for receiving an output signal of the operational circuit, for outputting a first control signal at a first output terminal and a second control signal at a second output terminal according to the input signal and the output signal; a second stage, coupled to the first stage, for generating the output signal according to a first driving current controlled by the first control signal and a second driving current controlled by the second control signal; and a protection circuit, coupled between the first stage and the second stage, for detecting the first driving current to selectively adjust the first control signal, wherein the protection circuit comprises: a first switch control element, for detecting the first driving current to generate a first switching signal; a first adjusting element, having a first terminal coupled to a first supply voltage; and a first switch element, having a first terminal coupled to a second terminal of the first adjusting element, and a second terminal selectively coupled to the first output terminal of the first stage according to the first switching signal, wherein the first adjusting element is operative to adjust the first control signal when the first switch element is switched on.