TCAN4550: TCAN4550 technology issue

Part Number: TCAN4550

Hi,

We have the technology issue for TCAN4550:

1. Pin impedance measurement: Comparing abnormal testing with normal materials, the impedance performance of each pin is completely consistent, preliminarily ruling out physical short circuits, open circuits, or leakage anomalies.
2. Key waveform testing (SPI_CK and CANH/L): 
   Abnormal chip: When sending data for the first time, although the waveform has output, the form is abnormal        (the level cannot be pulled down normally); When sending data again, the waveform is completely lost.
   Normal chip: Under the same testing conditions, both SPI_CK and CANH/L waveforms are normal.
3. Software log analysis: The TCAN4550 chip can be recognized normally when the system is powered on, but an error occurs when the driver reads its internal registers.
   1) Abnormal material, driving probe probability failure: tcan4x5x: probe of spi1.0 failed with error -22
   2) Chasing the driver, it was found that the TCAN driver reads the version register (0x1000) of the M-CAN     during the probe phase. If the read returns 0, the current driver will determine that the version is not   supported, resulting in probe failure and corresponding CAN network interface registration failure
   3) By using a script to cyclically read the M-CAN register 5000 times, there is a probability of approximately   10% for abnormal data to read a value of 0.
   4) Abnormal materials, even if the CAN node is registered normally, sending/receiving tests will still fail.
4. CAN FD speed:
   1) Abnormal material sending, normal material receiving: Data was not received normally
   2) Abnormal material receiving, normal material sending: There is a waveform sent, but the data is not received properly. The waveform on the bus shows an infinite retransmission due to the inability to receive an ACK response
   Classic CAN 1M speed:
   1) Abnormal material sending, normal material receiving: (30% probability) It can be sent and received normally in the first 3-5 occurrences, and abnormal materials cannot be sent thereafter.
   The SPI on the abnormal material side has no waveform, and the CAN bus also has no waveform; At this point, disconnect the bus of can0 and can1 through the command and reconnect them. Resending can send and receive the first 3-5 times, but sending abnormal materials will become abnormal again afterwards
   2) Abnormal material receiving, normal material sending: There is a waveform sent, but it is not received properly (uncertain if it is 100%, confirmation is needed). The waveform on the bus shows infinite retransmission due to the inability to receive ACK response
5. Please help to check the below schematic diagram and advise if there are any solution to solve this issue: