Systems and methods for protection of audio amplifier circuits

• US 20040184627A1
• Filed: 03/19/2004
• Published: 09/23/2004
• Est. Priority Date: 03/21/2003
• Status: Active Grant

• Current Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Original Assignee: D2Audio LLC (Renesas Electronics Corporation)
• Inventors: Andersen, Jack B., Kost, Michael A.
• Granted Patent: US 7,706,545 B2
• Time in Patent Office: Days
• US Class Current: 381/120
• CPC Class Codes: H03F 1/523 for amplifiers using field-effect devices H03F1/526 takes precedence
• CPC Class Codes: H03F 2200/331 Sigma delta modulation being used in an amplifying circuit
• CPC Class Codes: H03F 2200/342 Pulse code modulation being used in an amplifying circuit
• CPC Class Codes: H03F 2200/351 Pulse width modulation being used in an amplifying circuit
• CPC Class Codes: H03F 3/2171 with field-effect devices H03F3/2173 - H03F3/2178 take precedence
• CPC Class Codes: H03G 7/007 of digital or coded signals
• CPC Class Codes: H04L 7/005 Correction by an elastic buffer
• CPC Class Codes: H04L 7/02 Speed or phase control by the received code signals, the signals containing no special synchronisation information H04L7/0075 takes precedence

Abstract

Systems and methods for providing protection from failure events in a digital audio amplification system. One embodiment of the invention comprises a system having a digital amplifier controller, an amplifier output stage coupled to the controller and configured to receive audio signals from the controller, one or more sensors coupled to the output stage and one or more low-pass filters coupled to receive sensor signals from the one or more sensors. The low-pass filter is configured to filter the sensor signals and to provide the filtered sensor signals to the controller, which provides a programmable response to the filtered sensor signals. The response may range from not taking any action, to limiting the amplification of audio signals, to shutting down the system.

Claims

1. A system comprising:

a digital amplifier controller;

an amplifier output stage coupled to the controller and configured to receive audio signals from the controller;

one or more sensors coupled to the output stage ; and

one or more low-pass filters coupled to the one or more sensors and configured to receive sensor signals from the one or more sensors;

wherein the low-pass filters are configured to filter the sensor signals and to provide the filtered sensor signals to the controller; and

wherein the controller is configured to provide a programmable response to the filtered sensor signals.

2. The system of claim 1,

wherein the controller comprises a pulse width modulation (PWM) controller and the output stage comprises a PWM output stage;

wherein the system further comprises one or more comparators coupled to receive analog sensor signals from corresponding ones of the sensors and configured to generate binary sensor signal which are provided to corresponding ones of the low-pass filters;

wherein each low-pass filter comprises an accumulator configured to not assert the filtered sensor signal when a value in the accumulator is below a programmable threshold and to assert the filtered sensor signal when the value in the accumulator is above the threshold;

wherein the one or more sensors comprise at least one current sensor and at least one temperature sensor, and wherein the controller is configured to detect over-current and over-temperature conditions in the output stage; and

wherein the programmable response to the filtered sensor signals is selected from the group of responses consisting of;

shutting down the output stage;

and compressing at least a portion of the audio signals.

3. The system of claim 1, wherein the controller comprises a pulse width modulation (PWM) controller and the output stage comprises a PWM output stage.

4. The system of claim 3, wherein the one or more sensors comprise at least one current sensor, wherein the controller is configured to detect shoot-through current and to responsively adjust delays between a high-side signal and a low-side signal to minimize the shoot-through current.

5. The system of claim 1, further comprising one or more comparators, wherein each comparator is coupled to receive an analog sensor signal from a corresponding one of the sensors and to generate a binary sensor signal which is provided to a corresponding one of the low-pass filters.

6. The system of claim 5, wherein the one or more sensors comprise at east one current sensor.

7. The system of claim 5, wherein the one or more sensors comprise at east one temperature sensor.

8. The system of claim 1, wherein the low-pass filters comprise accumulators.

9. The system of claim 8, wherein the filtered sensor signal corresponding to each accumulator is not asserted when a value in the accumulator is below a threshold and is asserted when the value in the accumulator is above the threshold.

10. The system of claim 9, wherein the threshold is programmable.

11. The system of claim 1, wherein the controller is configured to receive filtered sensor signals from multiple sensors and to provide responses to each of the filtered sensor signals.

12. The system of claim 11, wherein the multiple sensors comprise at least one current sensor and at least one temperature sensor, and wherein the controller is configured to detect over-current and over-temperature conditions in the output stage.

13. The system of claim 1, wherein the programmable response to the filtered sensor signals is selected from the group of responses consisting of:

shutting down the output stage; and

compressing at least a portion of the audio signals.

14. A method comprising:

sensing a condition of an audio amplifier output stage;

providing a sensor output signal corresponding to the sensed condition;

low-pass filtering the sensor output signal to produce a filtered sensor signal;

providing the filtered sensor signal to an audio amplifier controller; and

providing a programmable response to the filtered sensor signal.

15. The method of claim 14, wherein the audio amplifier output stage comprises a pulse width modulated (PWM) output stage and wherein sensing the condition of the output stage comprises detecting a current through a transistor of the output stage.

16. The method of claim 15, further comprising detecting a shoot-through condition in the output stage.

17. The method of claim 16, further comprising adjusting relative delays between a high-side signal and a low-side signal input to the output stage to minimize shoot-through.

18. The method of claim 14, wherein the audio amplifier output stage comprises a pulse width modulated (PWM) output stage and wherein sensing the condition of the output stage comprises detecting a temperature of a transistor of the output stage.

19. The method of claim 14, wherein the audio amplifier output stage comprises a pulse width modulated (PWM) output stage and wherein sensing the condition of the output stage comprises detecting a temperature of a heat sink of the output stage.

20. The method of claim 14, wherein providing a sensor output signal corresponding to the sensed condition comprises sensing a voltage corresponding to the sensed condition, comparing the voltage to a reference value and generating a binary signal based upon the comparison.

21. The method of claim 14, wherein low-pass filtering the sensor output signal comprises incrementing and/or decrementing an accumulator based upon the binary signal and generating a signal indicative of whether a value in the accumulator is above or below a threshold value associated with the accumulator.

22. The method of claim 21, further comprising modifying the threshold value associated with the accumulator.

23. The method of claim 14, further comprising processing filtered sensor signals corresponding to multiple sensors through common logic in the controller.

24. The method of claim 14, wherein providing the programmable response to the filtered sensor signal is selected from the group consisting of:

shutting down the output stage; and

compressing at least a portion of the audio signals.