Slew-Rate Controlled Supply Voltage Switching for Glitch-Free Analog Modules
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Solution Overview
Problem
Electronic devices face disruptions when switching between power sources, such as batteries and AC adapters, due to supply voltage glitches and sudden changes, which can affect sensitive analog modules like phase locked loops and oscillators, leading to partial or full resets.
Innovation Solution
Implementing a slew rate regulation mechanism that controls the transition of the supply rail voltage when switching between power sources, using a controller circuit and slew rate regulator to manage the voltage change, thereby minimizing glitches and maintaining system stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If supply voltage switching is performed rapidly between power sources, then switching speed and responsiveness are improved, but supply voltage glitches and sudden changes occur that disrupt analog modules
Solution Approach 1:
The slew rate regulator is activated before the actual power source switching occurs to prepare the supply rail for controlled voltage transition. This preliminary action ensures that when switching happens, the voltage changes follow a controlled rate profile rather than occurring abruptly, thus preventing glitches while maintaining fast switching capability
Solution Approach 2:
The patent changes the temporal parameter of voltage transition by controlling the slew rate (rate of change of voltage with respect to time). By dynamically adjusting this parameter during switching transitions, the system achieves both fast switching and glitch-free operation, as the slew rate regulator ensures voltage changes occur within safe limits while still being rapid
2Reliability
If a dedicated IC pin is used for capacitor coupling to suppress voltage glitches, then reliability is improved, but device complexity and pin usage increase
Solution Approach 1:
The slew rate regulator is designed to serve multiple functions: it controls voltage transition rates during power source switching, suppresses supply voltage glitches, and protects analog modules. This multi-functionality eliminates the need for dedicated glitch suppression circuits and additional IC pins, reducing device complexity while maintaining reliability
Solution Approach 2:
The patent merges the power source switching control function with the voltage glitch suppression function into a single integrated slew rate control mechanism. By combining these functions rather than implementing them separately, the system achieves reliable glitch-free switching without requiring additional dedicated pins or components
Data Source
AI summary
An apparatus includes a slew rate regulation circuit, a plurality of switches and a controller circuit. The controller circuit controls the plurality of switches to decouple a first source supply voltage from a supply rail; control the plurality of switches to couple a second source supply voltage to the supply rail to replace the first source supply voltage with the second source supply voltage; and control the slew rate regulation circuit to regulate a slew rate of a voltage of the supply rail during a time interval in which the first source supply voltage is being replaced with the second source supply voltage.