Charge Pump Audio Amplifier Shutdown for Full Line-In Dynamic Range
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Solution Overview
Problem
Audio amplifiers powered by a single positive voltage supply have limited dynamic range, and when in shut down mode, the dynamic range of connected Line_In signals is further restricted due to the disabling of the charge pump circuit, leading to reduced peak-to-peak swing and potential damage from electrostatic discharges.
Innovation Solution
Separately controlling the operation of an audio amplifier and a charge pump to maintain a negative voltage supply rail, even in shut down mode, using diodes for electrostatic discharge protection and an external interface for digital/analog control, allowing the dynamic range to remain unchanged and preventing damage from electrostatic discharges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the charge pump circuit is disabled in shut down mode to isolate Line_In signals, then power consumption is reduced and isolation is improved, but the dynamic range of connected Line_In signals is limited
Solution Approach 1:
The patent separates the control of the audio amplifier and charge pump circuit into independent shutdown controls. The audio amplifier can be shut down while the charge pump continues operating, maintaining the negative voltage rail for Line_In signal dynamic range even when the amplifier is isolated. This segmentation allows independent optimization of power consumption and signal integrity.
2Use of energy by moving object
If the charge pump circuit is disabled in shut down mode, then power consumption is reduced, but the peak-to-peak swing of Line_In signals is reduced
Solution Approach 1:
The patent implements dynamic control where the charge pump circuit operates in different states based on system requirements. During normal operation, both amplifier and charge pump are active. During shutdown, the amplifier is disabled while the charge pump continues to maintain the negative voltage rail, providing dynamic adaptation to different operational modes while preserving Line_In signal capability.
3Device complexity
If the charge pump circuit is disabled in shut down mode, then device complexity is reduced, but protection from electrostatic discharges is compromised
Solution Approach 1:
The patent maintains the charge pump circuit and negative voltage rail in an active state during shutdown mode, performing preliminary preparation to ensure protection capabilities are already in place before any electrostatic discharge events. This preliminary action ensures that protection diodes remain reverse-biased and functional, ready to immediately protect against ESD without requiring additional activation steps.
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
Maintains a double dynamic range for audio signals by enabling them to swing between both positive and negative voltage rails in both operational modes, while preventing damage from electrostatic discharges and ensuring high impedance isolation from connected electronic devices.
Implementation Method 1
a charge pump circuit to synthesize a negative voltage supply rail (VSS)
Implementation Method 2
using diodes for electrostatic discharge protection
Data Source
AI summary
Separate control of the operation of an audio amplifier and a charge pump that synthesizes a negative voltage supply (VSS) for improving the dynamic range of the audio amplifier. The audio amplifier is typically powered by a single positive power supply (VDD) and the charge pump is arranged to synthesize a negative voltage supply rail (VSS) that enables a greater dynamic range for the amplifier's “on” and “shut down” modes of operation. Also, when the audio amplifier enters its shut down mode of operation to create at least some isolation from Line_In audio signals provided at the amplifier's output by other electronic devices, the amplifier's charge pump stays “on” and continues to provide the negative voltage supply rail (VSS). In this way, the greater dynamic range offered by the presence of both the positive and negative voltage rails is provided even if the amplifier is in a shut down mode.