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TCAN1042HGV: TCAN1042HGV: Power-up behaviour not clear

Nobbi1707
Prodigy 100 points
Part Number: TCAN1042HGV


Hello to all,

in our application out box must be silent during power up and during the power-up phase existing communication shall be not disturbed or corrupted.

In case of this the data sheet describes not clearly the power-up behaviour of this CAN-Transceiver (or I have not found the chapter).

The question is;

a) during power up of the 5V supply source how is the reaction of the external transceiver I/O's CANH and CANL  in the supply voltage range from 0V to  < Vcc_min ?
     Can we expect that these IO's will not impact the CAN bus?

b) during power up of the VIO supply source, how is the behaviour of the transceiver IO's CANH and CANL in the supply voltage range from 0V to <VIO_min ?

     Can we expect that these IO's will not impact the CAN bus?

My concern is, that the data sheet defines only when Vcc = VIO = 0V the then only the max. leakage current is flowing. But for the range between 0V and the min. supply voltage exists no statement.

Would be happy to get soon a reliable answer about my problem.

Thank you in advance

Norbert

  • 0
    TI__Guru 62920 points

    Hi Norbert,

    As VCC powers up, the CANH/CANL leakage will be very low <4.8 uA for VCC voltages ranging from 0 V to about 0.6 V.  Above that, there will be an increase in leakage (typically within 5~20 uA) as the VCC ramps up to its minimum value (UVVCC).  This is due to the receiver circuit becoming active and loading the bus via its input resistances which are biased to ground (see Figure 14 in the datasheet for reference).  Above UVVCC, the input resistances would either bias to GND (i.e., if VIO is not present or if VIO is active but STB is high) or to VCC/2 (i.e., if VIO is active and STB is low).

    Max