Type-C PD protocol chip while charging and listening

At present, most mobile phones on the market have been canceled 3.5mm Audio headphone connector , Keep only one Type-C Interface , But users who pursue sound quality and zero delay will still choose 3.5mm Wired headset , Because when playing mobile games , The asynchronous sound and picture really affects the game experience , therefore Type-C turn 3.5mm The interface line came into being .

If there is demand, there is market , This kind of Type-C turn 3.5mm As soon as the interface cable was launched, it became popular in the mobile phone accessories market , It is easy to use and solves the pain points of users , Naturally, there will be no shortage of orders . But after a while , The problem of listening to songs is solved , But the mobile phone can't be charged , This has created new pain points , Many manufacturers soon found this problem , Who can solve this pain first , Who can quickly seize the market , Everyone wants to be the first person to eat crabs , So the second generation audio adapter was quickly developed ！

 

There are three interfaces in the audio adapter , one end type-c Male connected mobile devices , one end type-c Female connection adapter , one end 3.5mm The audio interface connects the headphones , It seems simple, but it integrates many high and new technologies .

 

The original reason for adding charging is that users are playing mobile games , Electricity consumption is particularly fast , You can't charge it when you only connect headphones , So using this audio adapter can realize charging while playing , Audio charging is correct , It solves the user's pain points very well .

 

  When you don't need to recharge , Just plugging in headphones does not affect the use .

Next, let's see how to realize charging while listening to music ？ We studied several products , Open it and find the main IC There are two chips , One is the audio chip, which is responsible for converting digital signals to analog signals to output audio to headphones , The other is PD Protocol chip , Responsible for communicating with mobile phones PD Protocol communication .

 

First of all, let's get to know PD The principle of charging while listening to music in the Protocol , Mobile phones and PD Protocol chips belong to DRP, It is a dual role port . Before switching roles ,sink（ Power receiver ） Can only be UFP（ Slave ）,source（ Power supplier ） Can only be DFP（ host ）, For example, connect your mobile phone U At the time of the dish , Cell phone as source（ Power supplier ）,U Disk as sink（ Power receiver ）, So the cell phone will discharge to U Disk usage .

 

Although it is said that just doing role switching can realize charging while listening to music , But at present, there are a variety of mobile phone models on the market , And many mobile phones PD The agreement is not standardized , There are also many strange problems in the role switching process , At present, there are two conventional practices ：

 

For a more intuitive understanding of , We used the protocol analyzer to grab the mobile phone while charging and listening to music PD The agreement process , It uses cypress PD Protocol Analyzer ：

 

OPPO And vivo Series of mobile phones do role switching while charging while listening to music , If forced PR_Swap It may cause problems such as cell phone crash and restart , So here's the chip choice CC Disconnect and reconnect CC Set high , Let the chip do source（ Power supplier ） and DFP（ host ）, And then do it DR_Swap, Only switch data roles .

summary ：

It's tested here PD The protocol chip is from ledrui Technology LDR6028, This kind of PD The protocol chip is for USB Type-C Standard Bridge Developed for equipment USB-C DRP Interface USB PD Communication chip . Switching can be realized Data Role function , For smart devices ( The computer , Flat , mobile phone ) PDO And REQUEST negotiation , Automatically DR_SWAP To UFP Pattern .

LDR6028 characteristic ：

1. SOP-8 encapsulation , The periphery is streamlined

2. Support USB PD 2.0, compatible USB PD 3.0

3. For smart devices ( The computer , Flat , mobile phone ) 5V PDO And REQUEST negotiation

4. Automatically DR_SWAP To UFP Pattern

Main application scenarios ：

1.USB TYPE-C Adapter

2.USB Type-C HUB

Partial schematic diagram ：