S12ZVC CAN queries

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S12ZVC CAN queries

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NXP Employee
NXP Employee
  1. The maximum rating of CANH, CANL and split pin is as below, would there be a degradation if there is a transient on these pins greater than +60V. Is there any specification on the voltage level and time duration of the transients that the pins can withstand.  
  2. Isn’t the current being limited to 100mA on the CANH and CANL pins ? Over current threshold ?
  3. “A  supply  for  an  external  CANPHY  is  offered  via  external  device  pins  BCTLC  and  VDDC,  whereby BCTLC provides the base current of an external PNP and VDDC is the CANPHY supply (output voltage of the external PNP).”

       

    So,  what is the time that is required for (VDDC) the CAN physical layer to be powdered up after VSUP is supplied to the microcontroller. We need this information to determine the CAN setup time for our application.

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NXP TechSupport
NXP TechSupport

Hello Amit,

1.
This is not specified, the Maximum ratings are -32V; +40V (Table I-1, S12ZVC RM, rev. 2.1)

2.
This is the max. over-current threshold at which the transmitter gets disabled and the module goes to Listen-only mode.
But it can withstand up to 200mA as specified by the Maximum ratings.

3.
This is the same as the VDDX regulator, both are enabled out of POR.

You can refer to the below POR sequence from S12ZVM RM, rev.2.13
The VDDC regulator is enabled at the same time as the VDDX regulator.

pastedImage_1.png

Regards,

Daniel

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NXP Employee
NXP Employee

Hi,

1. Customer would  like to understand what would happen if there are transients that exceed the maximum ratings. I understand that the maximum rating is for continuous operation but will you able to tell us what would happen if there are transients on these pins greater than +/-60V. Will the pins be damaged ?

2. Doesn’t the CAN Physical Layer (S12CANPHYV3), have internal current limiting capability ?

 

Voltage spikes that look as below : Peak voltage would depend on the common mode choke, worst case +68V for time duration 500ns(Approx.)

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NXP Employee
NXP Employee

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NXP TechSupport
NXP TechSupport

Hello Amit,

1.

Besides the max DC voltage, the CANPHY is specified for ESD.

There is no other specification.

pastedImage_1.png

2.

When an over-current condition is detected, the transmitter is turned off which stops the current.

Regards,

Daniel

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