Abstract: Systems and methods for implementing over-current protection include reducing a clip level while an over-current condition is being detected. Once the over-current condition is no longer detected, the clip level is maintained for a specified period before allowing the clip level to be increased. In an embodiment, the specified period, for which the clip level is maintained before the clip level is allowed to be increased, starts when the over-current condition is no longer detected, and ends when each of N immediately preceding sample(s) of the audio signal are not clipped to the clip level, where N is an integer ?1. After an over-current condition is no longer detected, and after the clip level has been maintained for the specified period, the clip level can be increased if an over-current condition is not detected for a sample and the clip level is below a specified maximum clip level.

Abstract: Systems and methods for minimizing startup transients in digital audio controllers that may result in audible artifacts in the output of an audio amplification system. One embodiment comprises a digital PWM amplifier that includes a mechanism for controlling the amount of dead time in the audio output signal. When the amplifier starts up, the PWM signals provided to the output stage are simultaneously deasserted (i.e., there is dead time) for most of each switch period. The amount of dead time is gradually reduced over a series of switch periods until a nominal operating amount of dead time in each switch period is reached. Thus, the PWM signals are slowly ramped up from having a very large percentage of dead time (e.g., nearly 100%) to having a very small percentage of dead time (e.g., 1-2% to prevent shoot-through.

Abstract: Systems and methods for implementing over-current protection in amplifiers are provided, including systems, methods and devices for specifying a clip level at which to clip an audio signal in response to an over-current condition being detected. In an embodiment, the clip level is reduced while the over-current condition is being detected. Once the over-current condition is no longer detected, the clip level is maintained for a specified period before allowing the clip level to be increased. In an embodiment, the specified period, for which the clip level is maintained before the clip level is allowed to be increased, starts when the over-current condition is no longer detected, and ends when each of N immediately preceding sample(s) of the audio signal are not clipped to the clip level, where N is an integer, and N?1.

Abstract: Systems and methods for minimizing startup transients in digital audio controllers that may result in audible artifacts in the output of an audio amplification system. One embodiment comprises a digital PWM amplifier that includes a mechanism for controlling the amount of dead time in the audio output signal. When the amplifier starts up, the PWM signals provided to the output stage are simultaneously deasserted (i.e., there is dead time) for most of each switch period. The amount of dead time is gradually reduced over a series of switch periods until a nominal operating amount of dead time in each switch period is reached. Thus, the PWM signals are slowly ramped up from having a very large percentage of dead time (e.g., nearly 100%) to having a very small percentage of dead time (e.g., 1-2% to prevent shoot-through.

Abstract: A low delay corrector (LDC) unit includes a non-linear function generator and a filter. The nonlinear function generator receives a first signal and outputs a second signal in dependence on the first signal and a transfer function of the nonlinear function generator. The filter is fed in dependence on the second signal output by the nonlinear function generator. The first signal received by the nonlinear function generator is derived in dependence on an input signal provided to an input of the LDC unit and an output of the filter. An output of the LDC unit is derived in dependence on the first signal received by the nonlinear function generator and the second signal output by the nonlinear function generator.

Abstract: Power control systems generate electromagnetic interference (EMI). In at least one embodiment, a power control system includes a switching power converter and a controller that utilizes a spread spectrum strategy to reduce peak EMI values of the power control system. The controller generates a power regulation, switch control signal to control an input voltage to output voltage conversion by the switching power converter. The controller modulates the period of the control signal in accordance with the spread spectrum strategy. The spread spectrum strategy is an intentional plan to spread the spectrum of the control signal to reduce peak EMI values, and, thus, reduce the potential for degradation in performance, a malfunction, or failure of an electronic circuit caused by the EMI. The controller also modulates a pulse width of the switch control signal in response to modulation of the period of the control signal to provide power factor correction.

Abstract: Systems and methods for minimizing startup transients in digital audio controllers that may result in audible artifacts in the output of an audio amplification system. One embodiment comprises a digital PWM amplifier that includes a mechanism for controlling the amount of dead time in the audio output signal. When the amplifier starts up, the PWM signals provided to the output stage are simultaneously deasserted (i.e., there is dead time) for most of each switch period. The amount of dead time is gradually reduced over a series of switch periods until a nominal operating amount of dead time in each switch period is reached. Thus, the PWM signals are slowly ramped up from having a very large percentage of dead time (e.g., nearly 100%) to having a very small percentage of dead time (e.g., 1-2% to prevent shoot-through.

Abstract: In at least one embodiment, a controller allows triac-based dimmer to properly function and dim a load whose voltage is regulated by a switching power converter. In at least one embodiment, the switching power converter includes a switch to control voltage conversion of an input voltage to the switching power converter, wherein phase delays are introduced in the input voltage by a triac-based dimmer during a dimming period. In at least one embodiment, the controller is configured to control the switch of the switching power converter to establish an input resistance of the switching power converter during a dimming portion of the input voltage, wherein the input resistance allows the triac-based dimmer to phase modulate a supply voltage to the dimmer so that an output voltage of the dimmer has a substantially uninterrupted phase delay during each half-cycle of the supply voltage during the dimming period.

Abstract: A scan including data and shift inputs, and input selection circuitry for selecting between the data and shift inputs during normal, capture, and shift modes in response to only a first control signal and a second control signal. The input selection circuitry includes a first storage element for storing a bit representing a state of the first control signal in response to a change in state of the second control signals and multiplexing circuitry. The multiplexing circuitry is operable in the normal mode to select the data input in response to a first state of the second control signal, in the capture mode to select the data input when the bit stored in the first storage element represents a first state of the first control signal, and in the shift mode to select the shift input when the bit stored in the first storage element represents a second state of the first control signal.

Abstract: Systems and methods for performance improvements in digital switching amplifiers using low-pass filtering to reduce noise and distortion. In one embodiment, a digital pulse width modulation (PWM) amplifier includes a signal processing plant configured to receive and process an input audio signal. The amplifier also includes a low-pass filter configured to filter audio signals output by the plant. The filtered output of the plant is added to the input audio signal as feedback. The plant may consist of a modulator and power switch, a noise shaper, or any other type of plant. An analog-to-digital converter (ADC) may be provided to convert the output audio signal to a digital signal. Filtering may be implemented before or after the ADC, and a decimator may be placed after the ADC if it is an oversampling ADC.

Abstract: Systems and methods for ensuring proper phase alignment of audio signals which are processed by separate hardware channels in an audio amplification system. In one embodiment, the phase alignment is controlled by determining the number of audio data samples which are stored in the input buffers of multiple audio amplification units and controlling reads from the input buffers to minimize the difference between an actual read-write pointer differential and a target differential. In a master unit, the target differential is a predetermined target value corresponding to a desired delay in the buffer. The actual pointer differential of the master unit is passed to one or more slave units. The actual pointer differential of the master unit is used as the target differential of the slave units. The pointer differentials of the slave units are thereby driven to track the pointer differential of the master unit, keeping the units synchronized.

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.

Abstract: A low delay corrector (LDC) unit includes a non-linear function generator and a filter. The nonlinear function generator receives a first signal and outputs a second signal in dependence on the first signal and a transfer function of the nonlinear function generator. The filter is fed in dependence on the second signal output by the nonlinear function generator. The first signal received by the nonlinear function generator is derived in dependence on an input signal provided to an input of the LDC unit and an output of the filter. An output of the LDC unit is derived in dependence on the first signal received by the nonlinear function generator and the second signal output by the nonlinear function generator.

Abstract: Systems and methods for synchronizing multiple digital audio controller chips, wherein one of the chips is designated as a master and the other chips are designated as slaves. A common line connects all of the chips and is used to transmit synchronization signals from the master to the slaves. Each of the chips listens for an appropriate signal and, when the signal is detected, all of the chips simultaneously begin operation. In one embodiment, the synchronization signal comprises a transition on the shared line to an active state. The transition is repeated at fixed intervals and maintained in the active state for a fixed period in order to enable the chips to determine whether synchronization is being maintained. The signal may be sampled and/or filtered to improve reliability. The chips may be able to drive the shared line active to indicate that synchronization has been lost.

Abstract: Systems and methods for performance improvements in digital switching amplifiers using a low delay corrector. In one embodiment, a digital pulse width modulation (PWM) amplifier includes a signal processing plant configured to receive and process an input audio signal. The amplifier also includes a low delay corrector configured to receive signals output by the plant. The output of the low delay corrector is added to the input audio signal as feedback. The plant may consist of a modulator and power switch, a noise shaper, or any other type of plant. An analog-to-digital converter (ADC) may be provided to convert the output audio signal to a digital signal. Filtering may be implemented before or after the ADC, and a decimator may be placed after the ADC if it is an oversampling ADC.

Abstract: Systems and methods for implementing over-current protection in amplifiers are provided, including systems, methods and devices for specifying a clip level at which to clip an audio signal in response to an over-current condition being detected. In an embodiment, the clip level is reduced while the over-current condition is being detected. Once the over-current condition is no longer detected, the clip level is maintained for a specified period before allowing the clip level to be increased. In an embodiment, the specified period, for which the clip level is maintained before the clip level is allowed to be increased, starts when the over-current condition is no longer detected, and ends when each of N immediately preceding sample(s) of the audio signal are not clipped to the clip level, where N is an integer, and N?1.

Abstract: Systems and methods for improving the stability of feedback and/or feed-forward subsystems in digital amplifiers. One embodiment comprises a digital pulse width modulation (PWM) controller. The controller includes an input for receiving a digital audio input signal and is configured to generate a PWM output signal based on the input signal at an output. The controller also has control inputs for receiving external audio correction signals such as feedback and power supply feed-forward signals. The controller has correction circuitry for processing the received external control signals and modifying the input signal based on these signals. Fault detectors monitor fault conditions at various locations within the correction circuitry, and a protection control unit receives fault signals from the fault detectors and modifies operation of the controller in response to the fault signals.

Abstract: Systems and methods for minimizing startup transients in digital audio controllers that may result in audible artifacts in the output of an audio amplification system. One embodiment comprises a digital PWM amplifier that includes a mechanism for controlling the amount of dead time in the audio output signal. When the amplifier starts up, the PWM signals provided to the output stage are simultaneously deasserted (i.e., there is dead time) for most of each switch period. The amount of dead time is gradually reduced over a series of switch periods until a nominal operating amount of dead time in each switch period is reached. Thus, the PWM signals are slowly ramped up from having a very large percentage of dead time (e.g., nearly 100%) to having a very small percentage of dead time (e.g., 1-2% to prevent shoot-through.

Abstract: Systems and methods for performance improvements in digital switching amplifiers using a low delay corrector. In one embodiment, a digital pulse width modulation (PWM) amplifier includes a signal processing plant configured to receive and process an input audio signal. The amplifier also includes a low delay corrector configured to receive signals output by the plant. The output of the low delay corrector is added to the input audio signal as feedback. The plant may consist of a modulator and power switch, a noise shaper, or any other type of plant. An analog-to-digital converter (ADC) may be provided to convert the output audio signal to a digital signal. Filtering may be implemented before or after the ADC, and a decimator may be placed after the ADC if it is an oversampling ADC.

Abstract: Systems and methods for performance improvements in digital switching amplifiers using low-pass filtering to reduce noise and distortion. In one embodiment, a digital pulse width modulation (PWM) amplifier includes a signal processing plant configured to receive and process an input audio signal. The amplifier also includes a low-pass filter configured to filter audio signals output by the plant. The filtered output of the plant is added to the input audio signal as feedback. The plant may consist of a modulator and power switch, a noise shaper, or any other type of plant. An analog-to-digital converter (ADC) may be provided to convert the output audio signal to a digital signal. Filtering may be implemented before or after the ADC, and a decimator may be placed after the ADC if it is an oversampling ADC.