Self-Powered Analog Multiplexor Voltage Sensing Feedback
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Solution Overview
Problem
Conventional power management integrated circuits (PMICs) face challenges during the initial ramp-up stage due to the analog multiplexor being uncontrollable when the supply voltage is below a threshold, leading to uncertainty in output voltage and requiring an independent supply voltage, which complicates the feedback loop and increases die real estate usage.
Innovation Solution
A bypass switch is implemented in parallel with the analog multiplexor to short the supply voltage to its output when it's below the threshold, ensuring stable operation by directly feeding back the PMIC output, and automatically turning off once the supply voltage exceeds the threshold, allowing the multiplexor to select gated supply voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an independent supply voltage is provided to the analog multiplexor, then the multiplexor becomes controllable during ramp-up, but die real estate increases and ESD protection is required
Solution Approach 1:
The patent merges the supply voltage input and the control signal input by using the same CVDD supply for both the analog multiplexor operation and the control logic. This eliminates the need for a separate independent supply voltage, reducing die real estate while maintaining controllability during ramp-up through the self-powered control logic.
Solution Approach 2:
The CVDD supply voltage serves multiple functions simultaneously: it powers the analog multiplexor, drives the control logic, and enables the feedback function. This multi-functionality eliminates the need for dedicated independent supply voltage, reducing die area while ensuring the multiplexor remains controllable during the ramp-up phase.
2Reliability
If an independent supply voltage is provided to the analog multiplexor, then the multiplexor becomes controllable during ramp-up, but ESD protection and additional solder bumps are required
Solution Approach 1:
The patent combines the control signal generation and multiplexor operation into a single self-powered unit using CVDD. This integration eliminates the need for separate ESD protection circuits and additional solder bumps that would be required for an independent supply voltage, reducing device complexity while maintaining reliability.
3Loss of information
If the analog multiplexor is used during ramp-up, then voltage feedback is provided, but the output is unknown when supply voltage is below threshold
Solution Approach 1:
The patent implements preliminary action by ensuring the control logic is powered by CVDD before the multiplexor switching occurs during ramp-up. This preliminary power availability ensures that control signals are valid and deterministic from the start, eliminating unknown output states while providing accurate voltage feedback throughout the ramp-up phase.
Data Source
AI summary
A system and method are provided for regulating a supply voltage of a device. The method includes the steps of determining whether a supply voltage for an analog multiplexor is below a threshold voltage. If the supply voltage for the analog multiplexor is below the threshold voltage, then the method includes the step of shorting the supply voltage to an output of the analog multiplexor. However, if the supply voltage for the analog multiplexor is above or equal to the threshold voltage, then the method includes the step of transmitting at least one input signal coupled to the analog multiplexor to the output of the analog multiplexor. A system configured to implement the method may include a power management integrated circuit configured to generate a supply voltage for a device and a device that includes a self-powered analog multiplexor with voltage sensing bypass switch.