CPC G01R 19/0069 (2013.01) [H03F 3/217 (2013.01); H04R 3/00 (2013.01)] | 20 Claims |
1. A current detection circuit for a loudspeaker, applied to a loudspeaker connected to a class-D audio power amplifier, comprising: a first detection resistor, a second detection resistor, a sampling selection circuit, an input selection circuit, and a processing circuit, wherein,
one end of first detection resistor is connected to a first input end of the input selection circuit, a connection point of the one end of the first detection resistor and the first input end of the input selection circuit is functioned as a first input end of the current detection circuit for the loudspeaker, and the one end of the first detection resistor is connected to a source of a low-end NMOS transistor of an output stage VON of the class-D audio power amplifier;
one end of the second detection resistor is connected to a second input end of the input selection circuit, a connection point of the one end of the second detection resistor and the second input end of the input selection circuit is functioned as a second input end of the current detection circuit for the loudspeaker, and one end of the second detection resistor is connected to a source of a low-end NMOS transistor of an output stage VOP of the class-D audio power amplifier;
another end of the first detection resistor, another end the second resistor, and a third input end of the input selection circuit are all connected to ground;
a first output end of the input selection circuit is connected to a first input end of the processing circuit, and a second output end of the input selection circuit is connected to a second input end of the processing circuit;
an output end of the processing circuit is functioned as an output end of the current detection circuit for the loudspeaker;
three input ends of the sampling selection circuit are connected to a sampling clock, the output stage VOP, and the output stage VON respectively;
an output end of the sampling selection circuit is connected to a switch control end of input selection circuit; and
the sampling selection circuit is configured to: control, when a potential difference between the output stage VOP and the output stage VON is in a positive half period, the first input end of the input selection circuit to be electrically connected with the first output end of the input selection circuit, and the third input end of the input selection circuit to be electrically connected with the second output end of the input selection circuit; and control, when the potential difference between the output stage VOP and the output stage VON is in a negative half period, the third input end of the input selection circuit to be electrically connected with the first output end of the input selection circuit, and the second input end of the input selection circuit to be electrically connected with the second output end of the input selection circuit.
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