Analysis of common problems in TWS headset design

Today we summarize some common problems that are more likely to occur during the design process.

1. The two CC1 and CC2 pins of the TYPE-C USB charging case cannot be short-circuited together, and each must be connected to a pull-down resistor independently:

If CC1 and CC2 are short-circuited, the PD adapter will not charge the battery, because the PD device has a detection mechanism.

2. The distance between the Hall device and the magnet on the charging box should be controlled within 3MM. If it exceeds this distance, detailed reliability verification is required, because the magnet will demagnetize after high temperature. If the distance between the two is too far, the Hall sensor may fail.

3. The bottom of the charging ejector pin needs to have a PCB through hole, so that the reliability of the design is more guaranteed.

4. The MIC structure of the headset must have a sealed design, especially for projects with ANC and ENC functions.

5. The charging pins and pads on the headset PCB are recommended to be designed according to the following ratios:

Because if the ejector pin is larger than the PCB pad, the reliability will not pass, and there may be a risk of falling off during the barrel test.

6. The speaker of the headset should not be placed too close to the battery. The two are very likely to interfere with each other, especially some highly sensitive speakers, which are more likely to be interfered with, such as hearing noise. So be especially careful.

7. The length of the battery cable should be controlled well, as it will have some impact on RF.

8. Antenna: The stability of RF signal is the most core hard indicator. The antenna types are mainly ceramic antenna and FPC antenna. The performance indicators of the antenna and the location of the antenna must be verified before the mold is opened. Once the structural mold is finalized, it is difficult to change. The RF performance of PCBA is relatively easy to verify. The most troublesome thing is the coordination between PCBA and structure, and the coordination between antenna and structure is the most time-consuming.