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TCAN1044AV-Q1: TCAN1044AVDRBRQ1 Schematics check

Kevin Huang8
Genius 3825 points

Part Number: TCAN1044AV-Q1

Hi Team,

(1) When TCAN1044AVDRBRQ1 measures tLOOP1 of TP5 and TP6, there is a problem that it exceeds the data sheet MAX=210ns. The actual measurement is tLOOP1 = 292.2ns.
(2) Try to adjust C9 and C11 from 56pF to 2.2pF, and measure to tLOOP1 = 214.2n, but it still cannot meet the data sheet specification value.
(3) How to adjust the parts of C9 and C11 to see if they are correct? Or what parts should be adjusted to achieve tLOOP1 less than 210ns?

C9 and C11 from 56pF to 2.2pF, measure tLOOP1 = 214.2n

  • 0
    TI__Guru 71792 points

    Kevin,

    An engineer has been assigned this thread and will respond by end of business 03/05/2024.

    Regards,

    Eric Hackett 

  • 0
    TI__Mastermind 19070 points

    Hi Kevin,

    The 210ns loop delay specified in datasheet in based on test condition RL= 60 Ohms and CL = 100pF.

    If you need to test this specification, please use a standard termination of 60 Ohms, remove C9 and C11, and then connect a 100pF capacitive load between CANH/L lines.

    Regards,

    Sean

  • 0 in reply to Sean Guo
    Genius 3825 points

    Hi Sean,

    Because the system will connect other devices (motor controller and battery...etc.),
    Therefore, the terminal resistor cannot be a 60Ohm resistor as recommended in the specification.
    After connecting the entire device, the current measured terminal resistance value is about 120 Ohm. After measurement, tLOOP1 = 497.3ns is as shown below
    How to judge whether tLOOP1 is reasonable or within the reasonable range of use?

  • 0 in reply to Kevin Huang8
    TI__Mastermind 19070 points

    Hi Kevin,

    For me this loop delay time looks reasonable because the termination resistance is 120 Ohm, not the 60 Ohm specified in datasheet. Please note that 60 Ohm is not the recommended value, it's the test condition that our device guarantee to meet the specification. We can't guarantee a max loop delay time if your test condition is different with our datasheet.

    How will this 500ns loop delay affect your system? If the CAN bus can communicate normally it should not be a problem.

    Regards,

    Sean