Mute Control Circuit for Power-On and Power-Off Pop Suppression
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Solution Overview
Problem
Existing audio devices generate unwanted pop sounds during power-on and power-off due to uncontrolled coupling capacitor charging and discharging, which can damage the device and negatively impact user experience.
Innovation Solution
A low-cost and easily controlled mute control circuit is implemented, using a charge/discharge module and switch modules to output a high voltage level to the mute circuit during power-on and power-off, ensuring the mute circuit is activated and eliminating the pop sound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If software control is used to control the voltage level of enable pins, then the system can be controlled in normal operations, but the IO port becomes uncontrollable upon system power-on and power-off, causing pop sounds
Solution Approach 1:
The hardware control circuit is designed to automatically activate the mute function during power-on and power-off sequences before the software control system becomes operational or loses control. This preliminary hardware-based intervention ensures the mute circuit is engaged at the critical moments when pop sounds occur, resolving the reliability issue while preserving software control during normal operations.
2Reliability
If hardware control is implemented to control the voltage level of enable pins during power-on and power-off, then pop sounds can be eliminated, but the device complexity increases
Solution Approach 1:
A dedicated hardware control circuit acts as an intermediary between the power supply system and the mute circuit. This intermediary circuit automatically detects power-on and power-off states and triggers the mute function accordingly, eliminating the need for complex software intervention during these critical transitions while maintaining overall system simplicity.
Solution Approach 2:
The hardware control circuit is designed to autonomously detect power state changes and activate the mute function without requiring external control signals or complex coordination with the software system. This self-service capability simplifies the overall control architecture while ensuring reliable pop sound elimination during power transitions.
3Productivity
If the mute circuit is not activated during power-on and power-off, then the system operates normally during these processes, but pop sounds are generated that can damage the device and degrade user experience
Solution Approach 1:
The hardware control circuit implements preliminary anti-action by pre-activating the mute circuit during power-on and power-off sequences before any harmful pop sounds can be generated by the coupling capacitors. This proactive muting prevents the harmful acoustic output while allowing the power transition processes to complete normally.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively eliminates pop sounds during power-on and power-off, improving user experience and ensuring the reliability of the audio device by controlling the mute circuit through a high voltage level output.
Implementation Method 1
Due to the existence of a micro central unit (MCU), the software can control the voltage level of enable pins via an input/output (IO) port in normal operations of the system; however, the IO port is uncontrollable upon system power-on and power-off.
Implementation Method 2
the second switch module outputs a high voltage level to the mute circuit to control the mute circuit to be activated
Data Source
Figure 1~2
Figure 3~5
AI summary
A mute control circuit used upon power-on or power-off comprises a charge/discharge module, a first switch module and a second switch module. Upon power-on or power-off, charging or discharging is performed between the charge/discharge module and a power supply end. Upon charging or discharging, the charge/discharge module outputs a first level to the first switch module to control turning on of the same, and the first switch module outputs a second level to the second switch module to control turning on of the second switch module, such that the second switch module outputs a high level to a mute circuit to activate operation of the mute circuit. Also provided are a control method and an audio device.