Digital Delay Signal Output Circuit for Mute and Shutdown Timing
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Solution Overview
Problem
Conventional audio amplifier circuits require separate shutdown and mute signals, increasing the number of external pins and imposing a processing load on the controller, which can lead to inaccurate timing control and noise output when activating the amplifier.
Innovation Solution
A signal output circuit that uses a digital delay circuit to delay the control signal, allowing for accurate timing control of both shutdown and mute functions with a single external control signal, reducing the need for separate mute and shutdown signals and minimizing chip size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate shutdown and mute signals are used, then the shutdown and mute functions can be controlled independently, but the number of external pins increases and the processing load on the controller increases
Solution Approach 1:
The patent combines the shutdown and mute functions into a single integrated control mechanism. The shutdown signal is reused for both functions: when the shutdown signal is active, both the shutdown function and mute function are activated simultaneously. This eliminates the need for separate external pins while maintaining independent controllability through signal timing and internal circuit design.
Solution Approach 2:
The shutdown signal is designed to serve multiple purposes: it controls both the shutdown function (cutting power to the amplifier circuit) and the mute function (blocking the audio signal). This multi-functionality reduces the number of external pins required while maintaining the ability to independently control both functions through the single shutdown signal.
2Reliability
If separate shutdown and mute signals are used, then the shutdown and mute functions can be controlled independently, but the processing load on the controller increases
Solution Approach 1:
The patent merges the control of shutdown and mute functions into a single processing task. The controller only needs to manage one shutdown signal instead of two separate signals, reducing the processing load while maintaining independent functional control through internal signal distribution and timing mechanisms.
Solution Approach 2:
The internal circuit automatically distributes the single shutdown signal to control both shutdown and mute functions. The circuit includes internal switches and control logic that autonomously manage the signal routing, reducing the burden on the external controller while maintaining precise independent control of both functions.
3Device complexity
If shutdown and mute functions are controlled simultaneously by a single signal, then the number of external pins is reduced, but the timing control accuracy decreases leading to noise output
Solution Approach 1:
The patent implements preliminary action by ensuring the mute function is activated before the shutdown function when the shutdown signal is asserted. The internal circuit is designed so that the mute switch closes first to block the audio signal, then the shutdown switch opens to cut power. This sequential activation within the single signal response prevents noise by ensuring the audio path is already blocked before power cutoff.
Solution Approach 2:
The patent uses inverted control logic for the shutdown and mute functions. When the shutdown signal transitions to the active state (e.g., high level), the mute function is activated first (switch closes), and then the shutdown function is activated (switch opens). This inverted sequence ensures proper timing without requiring separate signals, preventing noise output during the transition.
4Area of stationary object
If the chip size is minimized by reducing external pins, then the device becomes more compact, but the timing control precision may be compromised
Solution Approach 1:
The patent merges multiple control functions into a single external pin interface, reducing chip size while maintaining timing precision through internal circuit design. The internal control logic and switch timing mechanisms are optimized to ensure precise sequential operation of the mute and shutdown functions despite using a single external signal.
Data Source
AI summary
A signal output circuit for controlling output of an input signal is disclosed. The signal output circuit includes an internal circuit, a digital delay circuit delaying by digital processing a control signal for controlling the operation of the internal circuit, and a switch muting the input signal in accordance with the output of the digital delay circuit.