USB Physical Layer Wake-Up for Low-Power Reconnection
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Solution Overview
Problem
Existing USB peripheral devices maintain high power consumption in sleep mode due to the presence of a power-on area, which is not conducive to power-saving.
Innovation Solution
An electronic apparatus with a low power wake-up mechanism that utilizes a physical layer circuit to detect logic state transitions in differential signal lines of a USB interface, restoring power to an upper layer circuit and modifying voltage states to detect plug-in and pull-out events, allowing for an initialization and enumeration process with the host apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a power-on area is maintained to store previous state information for quick reconnection, then the reconnection speed is improved, but the power consumption in sleep state increases
Solution Approach 1:
The patent extracts the state storage function from the upper layer circuit's power-on area and relocates it to the physical layer circuit's register. This allows the upper layer circuit to be fully powered off in sleep state while the physical layer circuit maintains minimal power operation to preserve state information, thus resolving the contradiction between quick reconnection and low power consumption.
Solution Approach 2:
The physical layer circuit acts as an intermediary between the upper layer circuit and the host apparatus. It stores state information in its register and manages the wake-up process by detecting USB bus events, enabling the upper layer circuit to be fully powered off while still supporting quick reconnection through the intermediary's state preservation capability.
2Use of energy by moving object
If the upper layer circuit is fully powered off in sleep state, then power consumption is reduced, but the wake-up and reconnection process becomes more complex
Solution Approach 1:
The patent segments the USB device into two independent functional parts: the physical layer circuit that remains partially active to monitor USB bus events and store state information, and the upper layer circuit that can be fully powered off. This segmentation allows the upper layer to achieve low power consumption while the physical layer handles the wake-up complexity through event detection and state management.
Data Source
AI summary
The present disclosure discloses an electronic apparatus having low power wake-up mechanism that includes an upper layer circuit and a physical layer. The upper layer circuit is powered off in a sleep state. The physical layer wakes up the upper layer circuit in the sleep state according to a logic state transition event that switches a pair of differential signal lines of a USB interface from a sleep logic state to a wakeup logic state such that a power of the upper layer circuit is restored. The physical layer modifies a voltage state of the differential signal lines to drive a host apparatus to detect a pull-out event and a plug-in event in series. The physical layer controls the upper layer circuit to perform initialization and enumeration process with the host apparatus to reconnect with the host apparatus.