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TCAN1057A-Q1: The communication rate issue

Zhang Liang
Genius 4925 points

Part Number: TCAN1057A-Q1

Hi,

When I used the TCAN1057A-Q1 chip to develop PCAN, the chip could only run up to 4M speed and could not

 communicate at 5M and above. The 4M speed communication waveform edge was slow during testing,

and the chip specification stated that it supports up to 8M. Replacing the NXP chip in the same testing environment

 worked normally, and the communication waveform edge was normal during testing. Is there any related case or

 possible reason for this?

The below is our schematic diagram:

151606d3e5a5b80df3ce1189352bd9d7.jpg

The below is our waveform for 4Mbps speed rate:

  1. RX;
  2. TX;
  3. CANH;
  4. CANL

d25f2798bbb8c1bd3c1a2f0bc2639216.jpg

 

  • 0
    TI__Guru 69647 points

    Hi Zhang,

    No known related case. However, the possible reason would most likely be due to the bus topology as described in 8.2.2.1 of the data sheet.

    Please help confirm which factor from 8.2.2.1 is applicable to your case while showing the 5M and above waveform (ours vs competitor showing which edge was slow - RXD? CANH / CANL?) for additional clarification. If RXD, may reduce the 100 ohms series resistor to confirm.

    Also note that CMC should be placed closer to the IC pin in general, similar to figure 8-7 of the data sheet, thanks.

    Best Regards,

    Michael.