PD chip refers to the device that supports USB Power Delivery (USB PD) protocol SN74HC164N Chip, which can realize high power fast charging and data transmission. The OTG mode (On The Go mode) refers to the mode of direct communication and data transmission between two USB devices without a host.
In the traditional USB charging, the charger can only provide a fixed voltage and current, and cannot be dynamically adjusted according to the needs of the charged device. The PD chip can provide appropriate voltage and current according to the needs of the charged equipment through negotiation protocol, so as to achieve more efficient and faster charging. At the same time, the PD chip also supports two-way communication and data transmission, which can realize data transmission while charging without additional data lines.
To realize OTG mode during charging, the PD chip needs the following functions:
1. Support USB PD protocol: The PD chip needs to support USB PD protocol and be able to negotiate power capacity and data. During negotiation, charging equipment and charged equipment will exchange capability information to determine appropriate voltage and current.
2. Support OTG mode: The PD chip needs to support OTG mode. Without a host, it can directly connect two USB devices and realize data transmission.
3. Support two-way communication: The PD chip needs to support two-way communication, and can charge and transmit data at the same time. In OTG mode, the charging device and the charged device can conduct two-way data interaction.
4. Support power switching: The PD chip needs to support power switching function, be able to switch from the charging device to the charged device, and realize data transmission. In the OTG mode, the charging device needs to be switched to the charged device to carry out two-way communication.
5. Support power management: The PD chip needs to support power management functions, which can dynamically adjust the output voltage and current according to the needs of charging devices and charged devices. In OTG mode, the PD chip needs to provide appropriate power output according to the capacity information of charging equipment and charged equipment.
The specific steps of OTG mode during charging are as follows:
1. Connection of charging device and charged device: connect the charging device and charged device to the PD chip via USB cable.
2. The PD chip negotiates the power supply capability: the charging device and the charged device will exchange capability information, including the supported voltage range, current range, etc. The PD chip determines the appropriate voltage and current output based on this information.
3. PD chip switches to the charged device: in OTG mode, the charging device needs to be switched to the charged device, and then the PD chip will switch the power output to the charged device.
4. Data transmission: In OTG mode, the charging device and the charged device can conduct two-way data transmission. The PD chip will provide a data path to support data interaction between the charging device and the charged device.
5. End of charging and data transmission: When charging and data transmission are completed, the PD chip will switch back to the charging device mode and stop power output as required.
To sum up, the PD chip needs to support USB PD protocol, OTG mode, two-way communication, power switching, power management and other functions to realize OTG mode when charging. Determine appropriate voltage and current output through negotiation protocol, and provide data path to realize charging and data transmission. In this way, OTG mode can be used during charging to achieve efficient and fast charging and data transmission.
