Rectifier circuit for monitoring DC offset of a single-supply audio power amplifier
An audio power amplifier arrangement includes an audio power amplification integrated circuit having two loudspeaker outputs. A rectifier circuit includes a first diode having a cathode connected to one of the two loudspeaker outputs and an anode connected to a rectifier output node. A second diode has an anode connected to the one loudspeaker output. A first resistor has a first end connected to a cathode of the second diode and a second end connected to the rectifier output node. A capacitor has a first end connected to the rectifier output node and a second end connected to electrical ground. A second resistor has a first end connected to the rectifier output node and a second end connected to electrical ground.
1. An audio power amplifier arrangement, comprising:
power amplifier arrangement, comprising:
an audio power amplification integrated circuit having two loudspeaker outputs; and
a rectifier circuit including:
a first diode having a cathode connected to one of the two loudspeaker outputs and an anode connected to a rectifier output node;
a second diode having an anode connected to the one loudspeaker output;
a first resistor having a first end connected to a cathode of the second diode and a second end connected to the rectifier output node;
a capacitor having a first end connected to the rectifier output node and a second end connected to electrical ground; and
a second resistor having a first end connected to the rectifier output node and a second end connected to electrical ground.
2. The arrangement of claim 1 further comprising a microcontroller connected to the rectifier output node.
3. The arrangement of claim 2 wherein the microcontroller includes an integral analog-to-digital converter.
4. The arrangement of claim 2 wherein the microcontroller is configured to place the audio power amplification integrated circuit in a low power stand by mode in response to detecting that a voltage at the rectifier output node is above a threshold level.
5. The arrangement of claim 4 wherein the threshold level is above two Volts.
6. The arrangement of claim 1 further comprising a comparator circuit connected to the rectifier output node.
7. The arrangement of claim 1 wherein a value of the capacitor is approximately between two microfarads and ten microfarads, and a value of the first resistor is approximately between 100,000ohms and 200,000ohms.
8. An audio power amplifier arrangement, comprising:
an audio power amplification integrated circuit having a loudspeaker output;
a rectifier circuit including:
a first diode having a cathode connected to the loudspeaker output and an anode connected to a rectifier output node;
a second diode having an anode connected to the loudspeaker output;
a resistor having a first end connected to a cathode of the second diode and a second end connected to the rectifier output node; and
a capacitor having a first end connected to the rectifier output node and a second end connected to electrical ground; and
means for detecting that a voltage at the rectifier output node is above a threshold level.
9. The arrangement of claim 8 further comprising means for removing voltage from the loudspeaker output in response to the detecting means detecting that the voltage at the rectifier output node is above the threshold level.
10. The arrangement of claim 9 wherein the removing means comprises a microcontroller.
11. The arrangement of claim 8 wherein the resistor comprises a first resistor, the rectifier circuit further comprising a second resistor having a first end connected to the rectifier output node and a second end connected to electrical ground.
12. The arrangement of claim 8 wherein the detecting means comprises a microcontroller.
13. The arrangement of claim 12 wherein the microcontroller includes an integral analog-to-digital converter.
14. The arrangement of claim 8 wherein the detecting means comprises a comparator circuit.
15. A method of processing an audio signal, comprising the steps of:
inputting the audio signal into a power amplification integrated circuit having a loudspeaker output;
connecting a rectifier circuit to the loudspeaker output, the rectifier circuit including:
a first diode having a cathode connected to the loudspeaker output and an anode connected to a rectifier output node;
a second diode having an anode connected to the loudspeaker output;
a resistor having a first end connected to a cathode of the second diode and a second end connected to the rectifier output node; and
as capacitor having a first end connected to the rectifier output node and a second end connected to electrical ground; and
detecting that a voltage at the rectifier output node is above a threshold level.
16. The method of claim 15 comprising the further step of removing voltage from the loudspeaker output in response to the detecting that the voltage at the rectifier output node is above the threshold level.
17. The method of claim 15 wherein the wherein the resistor comprises a first resistor, the rectifier circuit further comprising a second resistor having a first end connected to the rectifier output node and a second end connected to electrical ground.
18. The method of claim 15 comprising the further step of placing the power amplification integrated circuit in a low power stand by mode in response to the detecting that the voltage at the rectifier output node is above the threshold level.
19. The method of claim 15 comprising the further step of muting an associated audio channel in response to the detecting that the voltage at the rectifier output node is above the threshold level.
20. The method of claim 19 comprising the further steps of:
charging the capacitor through the second diode and the resistor; and
discharging the capacitor through the first diode.