Wireless Charging Circuit Bypass Path for NFC Startup
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Solution Overview
Problem
Wireless charging systems with shared antennas for NFC communication face challenges in meeting the 5 ms time requirement for initial communication to start after RF power rises, due to the stabilization time of switching regulators used for voltage reduction.
Innovation Solution
A wireless charging circuit with a voltage step-down circuit that includes a switching regulator and a selection circuit, allowing for a bypass path to supply voltage directly from the rectifier circuit to the communication controller during initialization, and switching to the switching regulator's output path once stabilized, along with a series regulator to reduce voltage in a shorter time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a switching regulator is used to reduce voltage from the rectifier circuit, then power loss is reduced and efficiency is improved, but the output voltage takes a long time to stabilize, making it difficult to meet the 5 ms communication startup requirement
Solution Approach 1:
The patent applies preliminary action by providing a bypass path that can supply voltage to the communication controller before the switching regulator is fully operational. The bypass circuit enables the communication controller to start up and perform initial communication within the 5 ms requirement, while the switching regulator continues to stabilize in the background. Once the switching regulator reaches a predetermined voltage level, the selection circuit switches to use its output, thereby meeting both the time constraint and efficiency requirements.
2Loss of energy
If a switching regulator is used for voltage reduction, then power loss in the IC is reduced, but the time from RF power rise to initial communication becomes excessively long
Solution Approach 1:
The patent applies dynamics by making the power supply path configurable and time-dependent. The selection circuit dynamically switches between the bypass path and the switching regulator output path based on the operational stage. During the initialization phase, the bypass path is active to enable fast communication startup. After the switching regulator stabilizes, the selection circuit transitions to using the switching regulator output, thereby optimizing power efficiency. This dynamic adaptation resolves the contradiction between fast startup and energy efficiency.
3Productivity
If the switching regulator output is used immediately, then power efficiency is improved, but the communication controller cannot start up within the required 5 ms timeframe
Solution Approach 1:
The patent introduces an intermediary solution in the form of a bypass circuit that mediates between the rectifier circuit and the communication controller during the startup phase. This bypass path acts as a temporary power supply that enables the communication controller to operate within the 5 ms requirement. The selection circuit then mediates the transition to the switching regulator output once it is ready, ensuring both startup capability and power efficiency are achieved at different stages of operation.
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
Enables compliance with NFC communication standards by ensuring initial communication can start within 5 ms of RF power rise, while minimizing power loss and heat generation through efficient switching operations.
Implementation Method 1
100 to 200 kHz is used as the carrier frequency for wireless charging which is the mainstream of the electromagnetic induction method
Data Source
AI summary
To satisfy the NFC communication standard in wireless charging with a shared antenna, used for NFC communication. A power supply unit includes a voltage step-down circuit 331, a charge control circuit 332, and a communication controller power supply circuit 333. The voltage step-down circuit includes a switching regulator 200, and a selection circuit 206 and 208 which can select an output path PT1 of the switching regulator and a bypass path PT2 of the switching regulator. The voltage step-down circuit includes a selection control circuit 207. The selection control circuit supplies voltage to the communication controller power supply circuit via the bypass path at the time of activating the communication controller. Since the output voltage of the series regulator stabilizes in a shorter time than the switching regulator, it becomes possible to keep the time from when RF power rises to when initial communication becomes possible, within standards.