Avoiding Clipping in Audio Power Transfer by Predicting Available Source Energy

Abstract

The power output circuit provides an audio power output signal, which is adjusted based on an estimate of the available energy from the power supply of the power output circuit when needed to prevent clipping. The power output circuit can be an audio power output circuit that generates an audio power output signal from samples of an audio program stored in a buffer. A processing block determines the energy requirements for generating the audio power output signal from the audio program and adjusts the amplitude of the audio power output signal according to the determined energy requirements and the available energy determined for the power supply so as to reproduce the audio power output signal without clipping occurring in the audio power output signal.

Description

Technical Field

[0001] Representative embodiments of the present disclosure pertain to audio or other power output methods, circuits, and systems having limited power capabilities and / or restricting the current / power supplied to one or more power output circuits. Background Art

[0002] An audio output stage that delivers power to an acoustic output transducer (e.g., a micro speaker or a speaker) is often a large energy consumer in energy-constrained devices such as mobile phones and other personal audio devices. If there is not enough voltage to provide an instantaneous audio power output signal corresponding to a full linear-scaled voltage waveform of the input program material, the result is distortion, i.e., "clipping". Various techniques have been provided to prevent such distortion, such as schemes for instantaneously boosting the power supply voltage, e.g., the so-called "Class G" and "Class H" amplifiers, so as to accurately reproduce the peak of the output waveform while the instantaneous energy demand increases. In some embodiments, when the boosting action raises the power supply voltage, the amplitude of the output waveform decreases.

[0003] However, such power-only or amplitude-only solutions only consider the current state of the available voltage and current, without considering the future state of the power supply voltage, resulting in inaccuracies.

[0004] Therefore, it would be advantageous to provide improved performance in an audio power output circuit, particularly when the audio power output circuit shares a power supply with other circuits. Summary of the Invention

[0005] Improved operation of audio circuits and systems can be achieved in an amplifier / signal processing system and an amplifier circuit and their operating methods.

[0006] The method, system, and circuit provide a power output signal from an output circuit. The power output circuit generates the power output signal from samples of an input program stored in a buffer. A processing block determines the energy demand for generating the power output signal from the input program and adjusts the amplitude of the power output signal based on the determined energy demand and the available energy determined for the power supply, so as to reproduce the power output signal without clipping in the audio power output signal. The power output signal can be an audio signal, and the input program can be an audio input program. Alternatively, the power output signal can be a signal for driving another electromechanical output transducer (e.g., a haptic feedback device).

[0007] The above summary is provided for brief description only and does not limit the scope of the claims. The following description sets forth example embodiments in accordance with the present disclosure. Further embodiments and implementations will be apparent to those of ordinary skill in the art. Those of ordinary skill in the art will recognize that various equivalent techniques may be applied in place of or in combination with the embodiments discussed below, and all such equivalent techniques are included in the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a block diagram of a system in which techniques according to embodiments of the present disclosure are implemented.

[0009] Figure 2 is a block diagram showing Figure 1 processing within signal processing block 20.

[0010] Figure 3 is a block diagram showing Figure 1 processing within capacitance estimator 30.

[0011] Figure 4 is a block diagram of a system in which techniques according to embodiments of the present disclosure are implemented.

[0012] Figure 5 is a graph depicting the operation of the system shown herein. DETAILED DESCRIPTION

[0013] The present disclosure includes methods, systems, and circuits for controlling the generation of an audio power output signal based on energy measurements associated with a power supply to prevent clipping or other distortion of the audio power output signal waveform. The technique uses measurements of the power supply output voltage, the power supply input voltage (e.g., battery terminal voltage), the current limit value provided by the power supply, and the power supply output capacitance value to calculate the available energy as the sum of the energy stored in the power supply output capacitance and the energy delivered through the power supply. Based on samples of the audio program input stored in a buffer of a delayed audio input program, the available energy is compared with the calculated energy required to deliver the output voltage waveform to one or more connected audio output transducers. If the available energy is insufficient to meet the output voltage waveform requirements of the samples in the buffer, the amplitude of the audio input program is reduced to generate an output voltage waveform that does not cause the demand to exceed the available energy, thereby preventing clipping of the output voltage waveform. The value of the power supply output capacitance can be updated through a calculation based on power conservation between the power supply input, the power provided to generate the audio power output signal, and the power resulting from the removal of energy from the output capacitance. The techniques described herein can be applied to other power output circuits, such as circuits that drive electromechanical devices (e.g., haptic feedback devices).

[0014] Figure 1A block diagram of an example amplifier system and circuit 10 is shown, in which techniques according to embodiments of the present disclosure are implemented. A power converter 14 delivers an operating voltage V SUPPLY to an amplifier 16, which generates an output voltage waveform 18 that is ultimately delivered to an audio output transducer, such as a micro speaker or speaker SPKR. Alternatively, the audio output transducer can be a haptic feedback device, such as a linear resonant actuator (LRA) or an eccentric rotating mass (ERM). The output of the power converter 14 is an output capacitor C O , which represents the total parallel output capacitance at the output of the power converter 14, including the effective output capacitance of any switching circuitry in the power converter 14 and any externally connected filter capacitance, etc. The input of the power converter 14 is shown connected to a battery 12, but the techniques herein can be applied to any power source suitable for providing an input voltage / current to the power converter 14. A series resistance R S represents the series internal resistance of the battery 12 and associated external circuit resistance, which results in a reduction in the battery terminal voltage V BATT , thereby resulting in a reduction in the energy / power delivered from the battery 12 to the power supply 14. In the illustrated system, if the terminal voltage V BATT of the battery 12 is reduced by the effective current limit provided by the power converter 14, the current consumed by the battery-powered circuit including the power converter 14 may decrease, which may result in a reduction in the output voltage V SUPPLY (which is the voltage across the output capacitor C O ) of the power converter 14. The above may occur when the output power delivered by the amplifier 16 is greater than the input power provided to the power converter 14. If the voltage V SUPPLY is lower than the supply voltage required to reproduce the output voltage waveform at the speaker SPKR, which is typically the amplitude of the output voltage waveform 18 plus the voltage drop due to the output resistance of the transistors generating the output of the amplifier 16, then the output voltage waveform 18 will be clipped at its maximum amplitude until the amplitude of the input signal decreases such that the output voltage waveform 18 can be generated again at full peak voltage.

[0015] To prevent clipping of the output voltage waveform, a signal processor 20 provides a processing subsystem that controls the amplitude of the signal V OUT provided to the input of the amplifier 16 such that when the signal processor 20 determines that the energy required for full reproduction of the input signal V IN is greater than a measured value of the available energy, the signal processor 20 reduces the amplitude of the signal V OUT , such that clipping of the output voltage waveform 18 does not occur. For clarity, the details of the signal processor 20 are omitted but will be described in further detail below with reference to other figures. This reduction reduces the amplitude applied to the input signal V INeither increases the gain or increases the attenuation, i.e., the signal processor relative to signal V OUT compresses signal V uniformly in both polarities OUT amplitude, thereby preventing clipping and asymmetric distortion. The signal processor 20 receives the battery terminal voltage V from the power converter 14 BATT value. It should be understood that the above technique can also prevent non-linear distortion from the amplifier 16 when the output voltage V SUPPLY of the power supply 16 approaches the voltage that the output voltage waveform 18 would present without reducing the gain in the signal processor 20 by including an offset in the required energy to accommodate any additional voltage required at the power input of the amplifier 16. The signal processor 20 requires the value of the output capacitance C O to determine the portion of the available energy stored in the output capacitance C O which can be a predetermined value, but in some embodiments of the present disclosure includes a capacitance estimator 30 which determines the value of the output capacitance C based on Figure 1 measurements within the circuit of O and will be further described in detail below with reference to Figure 3 . The capacitance estimator 30 also receives the input signal provided to the signal processor 20, which will be further disclosed in detail below and has been omitted from Figure 1 for clarity.

[0016] Although the following description is provided with reference to block diagrams, it should be understood that the descriptions and calculations included therein apply to processes that can be implemented by a digital signal processor of a computer program product executing embodiments of the present disclosure as further described in detail below. Additionally, the disclosed embodiments are discrete-time embodiments that calculate energy values and power values as sequences based on voltage measurements and sequential values of input samples. As used herein, "continuous" includes discrete-time sampling processes that are typically updated periodically at a predetermined sampling rate as a sequence of values.

[0017] Figure 2 is a block diagram depicting the gain control process applied to signal V Figure 1 by the signal processor 20 in the circuit. The power converter 14 receives the power input current I OUT and generates the power converter output voltage V amp provided to the amplifier 16. The calculation of the available energy E SUPPLY is performed by a summation operation 23 which sums the calculated value of the stored energy E AVAIL determined by the E STORE calculation block 22A with the energy E STORE available for the power converter calculated by the E IN calculation block 22B INThe calculated values of the maximum energy inputs are added. From E OUT Calculation block 22C calculates the required energy E required to generate the output voltage waveform 18 at full scale on the samples x[n] of the audio input V stored in the buffer 25 IN and, by dividing the available energy E OUT by the energy requirement E AVAIL calculates the energy ratio G OUT . Since the energy of the output voltage waveform 18 over time is proportional to the square of the voltage of the output voltage waveform 18, a square root calculation 26 is performed on the energy ratio G enrgy to obtain the voltage ratio G enrgy , which is the ratio of the desired amplitude of the output voltage waveform 18, to avoid clipping to the full scale amplitude of the output voltage waveform based on the audio input V voltage . To avoid expanding the output voltage waveform 18 beyond unity gain, a ceiling calculation 27 is performed to obtain the voltage ratio G IN and the minimum of unity: MIN(1, G voltage ), such that the output gain is never greater than unity. The gain control block is provided by multiplier 28, which scales the samples x[n] of the audio input V by the output gain from the ceiling calculation 27 VOLTAGE so as to reduce the amplitude of the output voltage waveform 18 when the available energy E IN is less than the energy requirement E AVAIL . OUT When the value of the power converter output voltage V

[0018] The energy calculations performed by the energy calculation blocks 22A - 22C are based on measured values and provided values. E STORE is not the total energy stored in the output capacitor C O but rather the difference between the total energy stored in the output capacitor C SUPPLY when the value of the power converter output voltage V O equals the value required to produce the instantaneous value of the output voltage waveform 18 without clipping and the energy stored in the output capacitor C O . Thus, the E STORE calculation block 22A calculates the stored energy as:

[0019]

[0020] E IN Calculation block 22B calculates the maximum available input energy that the power converter 24 can extract from the input power source based on a predefined current limit value I LIMIT and the actual terminal voltage V of the battery or other power source supplying energy to the power converter 24 BATT . E OUTThe calculation block 22C calculates the required energy E from the samples x[n] of the audio input V by integrating the power corresponding to a single sample on a continuous basis, i.e., IN where R OUT is the load impedance of the load connected to the output of the amplifier 16, and k is any gain or attenuation factor between the sample x[n] and the amplifier output waveform 18. Given the above values calculated by the energy calculation blocks 22A - 22C, the ratio of the available energy E

[0021]

[0022] to the required output energy E O is calculated, and the gain / attenuation factor gain is set as described above. AVAIL OUT

[0023] Figure 3 Shows Figure 1 the calculation details within the capacitor estimator 30 in the exemplary amplifier system and circuit 10. During the period when power conservation is accurate, the output capacitance C Figure 1 is estimated using power calculation according to the power conservation within the exemplary amplifier system and circuit 10 in O , which is during the period when the power converter 14 is in current limit as described below in the disclosed embodiments. During and across the above periods, the value of the estimated output capacitance C O is continuously updated to track the estimated output capacitance C O as it changes over time and temperature. The power P O provided by the output capacitance C CAP is calculated by the P CAP calculation block 32A and provided to the power converter 24, and the power P IN [n] is calculated by the P IN calculation block 32B and is given by:

[0024] P IN [n] = V BATT [n] I LIMIT [n].

[0025] The output power P OUT [n] provided by the amplifier 16 is calculated by the P OUT calculation block 32C and can be calculated as:

[0026] P OUT [n] = V OUT 2 / R L ,

[0027] where, R L ​​is the load impedance at the output of amplifier 16, and

[0028] P OUT [n] = V OUT 2 / R L = (gain x[n]) 2 / R L .

[0029] The subtraction operation 33B calculates the power removed from the output capacitor C by subtracting the input power P OUT [n] of the power converter 14 from the output power P IN [n], and the subtraction operation 33A calculates the power error P O due to the error in the estimation of the output capacitor C by subtracting the calculated power P O provided from the output capacitor C CAP . The accumulator 34 accumulates the calculated power error P O to produce the energy error E ERROR . As described in more detail below, since the power converter input power P ERROR [n] is determined based on the power supply current limit value I ERROR , the accumulator 24 is enabled for update by the control signal calculate_enable, which ensures that the capacitance estimator is updated only when the input of the power converter 24 is current-limited. The energy error E IN is scaled by the scaling operation 35, and the adder 36 scales the calculated error by a factor (k + 1). The error factor is multiplied by the nominal estimated starting capacitance value c_nominal by the multiplier 32, thereby producing the corrected capacitance value C LIMIT , which can be used in further calculations of the E ERROR calculation block 22A correted . Figure 2 of the E STORE .

[0030] The power calculations performed by the power calculation blocks 32A - 32C are based on measured values and provided values. As described above, the actual output power sequence P OUT is calculated by the P OUT calculation block 32C according to the input sample x[n] and the load resistance at the output of the amplifier 16. As described above, the input power sequence is calculated by multiplying the current limit value I LIMIT by the terminal voltage V BATT of the battery or other input power supply. The power provided by the energy consumed from the output capacitor C O is calculated as follows:

[0031]

[0032] It can be calculated by the finite difference between the sampled value of the output voltage V of the power supply and the instantaneous estimated value of the output capacitor C SUPPLY : C[n]. O

[0033] Now refer to Figure 4 , which shows a digital signal processing system that can be used to implement the technology of the present disclosure. A digital signal processor (DSP) 42 (or a suitable general-purpose processor) executes program instructions stored in a non-volatile memory 44 and forming a computer program product according to the present disclosure. The DSP 42 receives an audio input signal V IN at the input terminal INPUT from a program source (e.g., CODEC). The DSP 42 also receives samples of the output voltage V SUPPLY of the power converter 24 from the ADC 41B serving as a voltage measurement circuit, and receives the current limit I LIMIT of the battery 12 and the value of the battery terminal voltage V BATT from the power converter 14. A digital-to-analog converter (DAC) 43 receives the output value corresponding to the processed amplifier output signal V OUT , which represents the audio input samples that have been processed according to the process described in reference Figure 2 and Figure 3 to prevent clipping or other distortions due to insufficient available energy from the power converter 14 and the output capacitor C O . The DAC 43 provides the output signal V OUT to the amplifier 46 that generates the output voltage waveform 18. Alternatively, the DSP 42 can provide samples to a pulse width modulator (PWM) (class D) type amplifier, or generate a PWM signal directly provided to a conversion circuit, and the conversion circuit is supplied with the power supply voltage V O provided by the power converter 14 and the output capacitor C SUPPLY .

[0034] Refer to Figure 5 , the graph shows an example operation of the amplifier described above with reference Figure 1-4 . The available energy E AVAIL is shown to occasionally drop below the required energy E OUT , and the value of gain is reduced by the actions of the above-described processing of these intervals, so that clipping of the output voltage waveform 18 does not occur.

[0035] ​As described above, some or all of the disclosed processes can be implemented by executing a set of program instructions that form a computer program product stored on a non-volatile memory, but it also exists in a tangible storage form as a computer-readable storage medium outside the non-volatile memory. The computer-readable storage medium can be, for example, but not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. Specific examples of the computer-readable storage medium include the following: hard disks, semiconductor volatile and non-volatile storage devices, portable compact disc read-only memories (CD-ROMs) or digital versatile discs (DVDs), memory sticks, floppy disks, or other suitable storage devices not specifically enumerated. The computer-readable storage medium used herein should not be construed as a transient signal, such as a transmission line or a radio wave or an electrical signal transmitted through a wire. It should be understood that the blocks of the above block diagrams can be implemented by computer-readable program instructions. These computer-readable program instructions can also be stored in other storage forms as described above and can be downloaded into the non-volatile memory for execution therefrom. However, a set of instructions stored on a medium other than the non-volatile memory of the above system also constitutes a computer program product, which is a manufactured article including instructions for implementing aspects of the functions / actions specified in one or more of the block diagrams.

[0036] In summary, the present disclosure discloses a power output circuit that provides a power output signal, which is adjusted based on an estimate of the available energy from a power supply for an amplifier when needed to prevent clipping. The power output circuit generates the power output signal from program samples stored in a buffer. A processing block determines the energy requirements for generating the power output signal from the program and adjusts the amplitude of the power output signal according to the determined energy requirements and the available energy determined for the power supply so as to reproduce the power output signal without clipping of the power output signal. The system provides the power output signal to an output transducer based on the program and includes a power supply, a buffer for storing program samples, a power output circuit that generates the power output signal from the program samples, and a processing subsystem that determines the energy requirements for generating the power output signal from the program and adjusts the amplitude of the power output signal according to the determined energy requirements and the available energy determined for the power supply so as to reproduce the power output signal without clipping of the power output signal. The program can be an audio program, and the power output signal can be an audio power output signal. Alternatively, the power output signal can be a signal for driving another electromechanical output transducer (such as a haptic feedback device).

[0037] The processing subsystem may determine the available energy of the power output circuit by determining the stored energy in the output storage capacitor of the power supply, determining the available input energy at the input end of the power supply, and the available input energy at the input end of the combined power supply circuit and the stored energy in the output storage capacitor, and determine the available energy from the power supply circuit. The processing subsystem adjusts the amplitude of the power output signal according to the determined available energy of the power output circuit. The processing subsystem may calculate the energy demand based on the sample of the input signal stored in the buffer, and compare the energy demand with the available energy of the power output circuit to determine the gain or attenuation value applied to the power output signal. The processing subsystem may also estimate the capacitance value of the output storage capacitor, and use the estimated capacitance value to determine the energy stored in the output storage capacitor. The processing subsystem may calculate the capacitance value based on the conservation of the power provided from the output storage capacitor, the power provided to the input end of the power supply, and the power provided to the power output circuit. The system may also include a voltage measurement circuit for measuring the voltage on the output storage capacitor, and determining the power provided from the output storage capacitor according to the calculated capacitance value and the change in the measured voltage. When the input of the power supply is in a current limiting state, the processing subsystem can calculate the power provided to the power input terminal based on the current limit value of the power supply and the voltage on the power input terminal, and the capacitance value can be calculated only when the power supply is in a current limiting state. Based on the estimated capacitance, the processing subsystem can also determine the error in the estimated capacitance value by subtracting the power provided to the power input terminal and the power provided from the capacitor from the power value representing the power delivered to the power output circuit. The processing system can then accumulate the results of the subtraction to produce an energy error value and update the estimated capacitance value based on the energy error value. The processing subsystem can update the estimated capacitance value so that when determining the available energy from the power supply, the change in capacitance of the output storage capacitor over time is modeled and compensated.

[0038] Although the present disclosure has shown and described particular embodiments of the technology disclosed herein, it will be understood by those skilled in the art that the foregoing and other changes in form and detail may be made without departing from the spirit and scope of the present disclosure. For example, the technology of the disclosed embodiments may be combined with other compression algorithms (e.g., equal loudness curves) to provide a combined reduction in volume when required due to power limitations or for signal enhancement.

Claims

1. A method for preventing clipping in a power output circuit that provides a power output signal, the method comprises: determining available input energy at an input terminal of the power supply by determining stored energy in an output storage capacitor of the power supply; and determining available energy from the power supply that provides the power output circuit by combining the available input energy at the input terminal of the power supply circuit and the stored energy in the output storage capacitor to determine the available energy of the power output circuit; calculating an energy requirement for generating the power output signal; and adjusting an amplitude of the power output signal according to the energy requirement and the determined available energy of the power output circuit so as to reproduce the power output signal without clipping occurring in the power output signal.

2. The method according to claim 1, wherein the power output circuit is an audio power output circuit for providing an audio power output signal to an electroacoustic output transducer.

3. The method according to claim 1, further comprising buffering samples of an input signal reproduced by the power output circuit to provide the power output signal, and wherein the calculating the energy requirement is based on the samples of the input signal in the buffer to calculate the energy requirement.

4. The method according to claim 1, further comprising comparing the energy requirement with the available energy of the power output circuit to determine a gain or attenuation value applied to the power output signal.

5. The method according to claim 1, further comprising estimating a capacitance value of the output storage capacitor, and wherein the determining the stored energy in the output storage capacitor of the power supply is using the estimated capacitance value to determine the stored energy.

6. The method according to claim 5, wherein the estimating the capacitance of the output storage capacitor is calculated according to the conservation of power provided from the output storage capacitor, power provided to the input terminal of the power supply, and power provided to the power output circuit.

7. The method according to claim 6, further comprising measuring a voltage across the output storage capacitor, wherein the power provided from the output storage capacitor is determined according to the estimated capacitance value and a change in the measured voltage.

8. The method according to claim 7, wherein when the input terminal of the power supply is in a current limiting state, the power provided to the input terminal of the power supply is calculated according to a current limit value of the power supply and a voltage across the input terminal of the power supply, and wherein the estimating the capacitance of the output storage capacitor is calculated only when the power supply is in the current limiting state.

9. The method according to claim 6, further comprises: determining an error in the estimated capacitance value by subtracting, according to the estimated capacitance value, the power provided to the input terminal of the power supply and the power provided from the capacitor from a power value representative of the power delivered to the power output circuit; accumulating the result of the addition and subtraction to generate an energy error value; and updating the estimated capacitance value according to the energy error value.

10. The method according to claim 9, wherein Perform the determining of the error and the updating to model and compensate for changes in the capacitance of the output storage capacitor over time when determining the available energy from the power supply.

11. A system for providing a power output signal to an output transducer based on a program, the system comprising: A power supply; A buffer for storing samples of the program; A power output circuit that generates the power output signal from the samples of the program; and A processing subsystem that determines the energy requirements for generating the power output signal from the program and adjusts the amplitude of the power output signal based on the determined energy requirements and the available energy determined for the power supply so as to reproduce the power output signal without clipping of the power output signal, wherein the processing subsystem determines the available energy by determining the stored energy in the output storage capacitor of the power supply, determining the available input energy at the input terminal of the power supply, and combining the available input energy at the input terminal of the power supply circuit and the stored energy in the output storage capacitor to determine the available energy for the power output circuit, and wherein the processing subsystem adjusts the amplitude of the power output signal based on the energy requirements and the determined available energy.

12. The system according to claim 11, wherein, The power output circuit is an audio power output circuit for providing an audio power output signal to an electroacoustic output transducer, and wherein the program is an audio program.

13. The system according to claim 11, wherein, The processing subsystem calculates the energy requirements based on samples of an input signal stored in the buffer.

14. The system according to claim 13, wherein, The processing subsystem compares the energy requirements with the available energy of the power output circuit to determine a gain or attenuation value to be applied to the power output signal.

15. The system according to claim 11, wherein, The processing subsystem estimates the capacitance value of the output storage capacitor and uses the estimated capacitance value to determine the stored energy in the output storage capacitor.

16. The system according to claim 15, wherein, The processing subsystem calculates the capacitance value based on the conservation of power provided from the output storage capacitor, the power provided to the input terminal of the power supply, and the power provided to the power output circuit.

17. The system according to claim 16, further comprising a voltage measurement circuit for measuring the voltage across the output storage capacitor, wherein, The power provided from the output storage capacitor is determined based on the calculated capacitance value and the change in the measured voltage.

18. The system according to claim 17, wherein, The processing subsystem calculates the power provided to the input terminal of the power supply based on the current limit value of the power supply and the voltage at the input terminal of the power supply when the input terminal of the power supply is in a current limiting state, and wherein the processing circuit calculates the capacitance value only when the power supply is in a current limiting state.

19. The system according to claim 16, wherein, The processing subsystem also determines an error in the estimated capacitance value by subtracting the power supplied to the input of the power supply and the power supplied from the capacitor from a power value representative of the power delivered to the power output circuit, based on the estimated capacitance, wherein the processing subsystem accumulates the result of the addition and subtraction to produce an energy error value and updates the estimated capacitance value based on the energy error value.

20. The system according to claim 19, wherein, the processing subsystem updates the estimated capacitance value to model and compensate for the change over time of the capacitance of the output storage capacitor when determining the available energy from the power supply.

21. A system for providing an audio power output signal to an audio output transducer based on an audio program, the system comprising: a power supply; a buffer for storing samples of the audio program; an audio power output circuit that generates the audio power output signal from the samples of the audio program; and a processing subsystem that determines the energy requirements for generating the audio power output signal from the audio program and adjusts the amplitude of the audio power output signal based on the determined energy requirements and the available energy determined for the power supply, so as to reproduce the audio power output signal without clipping of the audio power output signal, wherein the processing subsystem determines the available energy by determining the stored energy in an output storage capacitor of the power supply, determining the available input energy at the input of the power supply, and combining the available input energy at the input of the power supply circuit and the stored energy in the output storage capacitor to determine the available energy for the audio power output circuit, and wherein the processing subsystem adjusts the amplitude of the power output signal based on the energy requirements and the determined available energy.

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