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SN65HVD251D at > 1Mbit/s

R. Scalick
Prodigy 160 points

Hi,

I have done the following investigations regarding SN65HVD251D at high speed.

I have tested with two SN65HVD251D (one as the transmitter and one as the receiver) with a square wave generator at the D pin with the following input frequ.:

100kHz, 500kHz, 1MHz and 3MHz, I found out that the duty cycle is up to 500kHz (1Mbit/s) 50:50, but if I am increasing the frequ, the duty cycle will change to 35:65. Is this a normal behaviour ?

Additional I would like to ask, If we can use the  SN65HVD251D connected to the UART of the controller (as levelshifter without CAN functionality) with a higher datarate (2 up to 3Mbit) ? see above mentioned duty cycle behaviour....

many thanks and kind regards

Rudi

 

 

  • 0
    TI__Mastermind 21801 points

    Hi Rudi,

    Are you saying that even though you drive a 50% duty cycle waveform into the device, the bus duty cycle is not keeping up?

    Either way the device is only rated for speeds up to 1MBPS, per the ISO18898-2 & -5. This device was not designed for 3MBPS.

    CAN transceivers are usually controlled by a processor with a built in CAN controller. You can think of the controller as a sort of MAC that does protocol level bit-stuffing and error checking in hardware. Therefore, a standard UART will not be able to do these same functions that a CAN controller is designed to handle.

    Thanks,

    John