USB Sink Device CC Terminal Grounding Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In configurations where multiple sink devices are connected to a host device via USB, the parallel connection of pull-down resistors at Configuration Channel (CC) terminals can lead to erroneous detection of power-supplying capability, causing issues such as stopping USB charging due to voltage division.
Innovation Solution
The electronic device includes a control unit that manages the grounding state of pull-up or pull-down resistors at the CC terminals, ensuring accurate detection by disabling the pull-down resistor for one sink device connected directly to the host and enabling it for other sink devices, thereby preventing voltage division and ensuring proper power supply detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple sink devices are connected to a host device via USB with pull-down resistors at CC terminals, then multiple devices can be supported for charging, but voltage division occurs causing erroneous detection of power supplying capability
Solution Approach 1:
The control unit determines the connection state of sink devices before detecting power supplying capability. By checking connection status in advance and selectively connecting or disconnecting pull-down resistors based on the determination result, the system performs preliminary configuration to prevent voltage division during power capability detection.
Solution Approach 2:
The pull-down resistor connection state is dynamically changed based on the connection status of sink devices. The control unit connects or disconnects the pull-down resistor according to whether a sink device is detected, making the electrical configuration adaptive rather than fixed, thereby preventing voltage division when multiple devices are connected.
2Adaptability or versatility
If pull-down resistors are connected in parallel at CC terminals of multiple sink devices, then multiple devices can be connected to host, but voltage division causes stopping of USB charging power supply
Solution Approach 1:
The control unit determines the connection state of sink devices before detecting power supplying capability. By checking connection status in advance and selectively connecting or disconnecting pull-down resistors based on the determination result, the system performs preliminary configuration to prevent voltage division during power capability detection.
Solution Approach 2:
The pull-down resistor connection state is dynamically changed based on the connection status of sink devices. The control unit connects or disconnects the pull-down resistor according to whether a sink device is detected, making the electrical configuration adaptive rather than fixed, thereby preventing voltage division when multiple devices are connected.
Data Source
AI summary
An electronic device that is able to operate by receiving a power supply from a host device through a Universal Serial Bus (USB). The electronic device acts as a first sink device and is connected to a second sink device that is able to operate by receiving a power supply from the host device through the USB and the connection to the first sink device. Each of the first sink device and the second sink device is provided with a CC terminal that obtains power supplying capability information from the host device, a pull-up or pull-down resistor connected to the CC terminal, and a GND terminal that grounds a circuit of the CC terminal and the pull-up or pull-down resistor. The electronic device changes a state of grounding of the pull-up or pull-down resistor to the GND terminal, in one of the first sink device and the second sink device.