I am testing a BQ500212A board designed myself these days. I've got some problems.
The main issue is that even though the Rx is placed on the Tx coil, it still doesn't start charging. It seems like the Hand-Shaking process has failed. The BQ500212A switches the TLV70033 on and off contently, just like there is no Rx on the coil surface.
I also have some queries
1. Is it possible that the pulse time is too short for the communication between Rx and Tx? I measured the waveform of the RC circuit and found that the pulse time is about 85ms and the interval between two neighboring pulse is about 450ms.
2. Will it influence a lot if I use COMM resistors with accuracy of 5%? The waveform between COMM+ and COMM- shows that the communicating signals is weak, I am not sure is that normal.
3. I imitate the PCB layout from the 500212A EVM board.
My brain is very chaotic. That's all descriptions I can present. I really want and appreciate someone can give me some help. If you want to see the waveform, please inform me where I should measure.
Here are the schematic and gerbe files:
Thank you for your patient!