Amplifier speaker drive current sense

A speaker drive and current measurement system, comprising:

• a transistor bridge comprising:
• two high-side switching transistors;
• a first low-side switching transistor;
• a second low-side switching transistor;
• a first sense resistor that connects the first low-side switching transistor to a low-side reference voltage;
• and
• a second sense resistor that connects the second low-side switching transistor to the low-side reference voltage;
• a sigma delta analog to digital converter (ΣΔ ADC) coupled to the bridge, the ΣΔ ADC comprising:
• a first digital to analog converter (DAC) dedicated to measurement of voltage across the first sense resistor;
• and
• a second DAC dedicated to measurement of voltage across the second sense resistor.

An audio amplifier, comprising:

• a driver configured to drive a speaker;
• and
• a current monitoring system configured to measure the current output by the driver;
• wherein the driver comprises:
• two high-side transistors and two low-side transistors connected as a bridge to drive the speaker;
• a first sense resistor connected between a first of the low-side transistors and a low-side reference voltage;
• a second sense resistor connected between a second of the low-side transistors and the low-side reference voltage;
• wherein the current monitoring system comprises a sigma delta analog to digital converter (ΣΔ ADC) coupled to the driver to measure voltage across the first sense resistor and the second sense resistor, the ΣΔ ADC comprising:
• a differential amplifier;
• a first switch to switchably connect one of a positive side of the first sense resistor or a negative side of the second sense resistor to a first input of the differential amplifier;
• a second switch to switchably connect one of a positive side of the second sense resistor or a negative side of the first sense resistor to a second input of the differential amplifier;
• a first digital to analog converter (DAC) dedicated to measurement of voltage across the first sense resistor;
• and
• a second DAC dedicated to measurement of voltage across the second sense resistor.