Since the USB-IF organization released the USB type-c standard in 2013 and LeEco released the first USB type-c interface phone in 2014, the popularity of the USB c interface has become an irreversible trend. Up to now, there are only two types of interfaces left in mobile phones: USB type-C and Lighting. In the future, there is even hope of unifying it to only one USB C interface, and even the 3.5mm headphone jack will be unified into the USB C interface. But this raises a question, what if users want to use wired headphones to listen to music while charging their phones? So, the USB type-C interface adapter emerged.

This adapter transforms one C port into two C ports, with one side connected to a charger and the other side connected to USB C headphones, greatly facilitating consumer use. However, many engineers have found that in the design of products, in the USB C interface, if you want to achieve charging while listening to music, it is not like the previous micro USB interface, which only needs to provide both power and audio interfaces and utilize the OTG function of the phone to achieve it. But it requires a USB PD chip to communicate with the phone in order to achieve simultaneous charging and listening. Otherwise, either you can only listen to music or you can only charge.

We purchased various listening and charging adapters on Amazon and Taobao for disassembly and learning, and found that. There is a similar USB PD control chip LDR6023C inside. After consulting the chip manufacturer Shenzhen Ledrui Technology Co., Ltd., we obtained the development information and contact information of the original factory for this chip. You can see that this chip is like this:

This chip can communicate with both the phone and the charger in PD mode, allowing the phone to enter USB HOST mode (by default, the phone is in USB device mode) while charging, thus smoothly achieving the function of listening while charging. It is commendable that this chip can support both digital and analog earphones (detected through pin3), with excellent compatibility. The following is the application circuit diagram of this chip:

From the circuit diagram, it can be seen that the peripheral of this chip is very simple. While providing analog headphone detection function, it can also be configured for power through pin4. Limit the maximum voltage to within 9V to reduce the voltage resistance requirements for other components on the board, reduce volume and cost.

Source: Charging head network