About the pull up resistor in LIN PHY on S12ZVL

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About the pull up resistor in LIN PHY on S12ZVL

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ikkishingu
Contributor II

Hello,

Could you tell me about the pull up resistor in LIN PHY on S12ZVL?

We can select the internal pull up(34kohm/330kohm) in LIN PHY, then what is the purpose of this selectable implementation?

For buildup against the bus noise or surges?

Ikki

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iggi
NXP Employee
NXP Employee

The 34K is the typical pull-up resistor on LIN module. The 330K pull-up option is used to decrease leakage current in shutdown mode and to decrease current consumption in standby mode.

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iggi
NXP Employee
NXP Employee

Hi,

Actually you cannot select. You can just enable internal pull-up.

As per datasheet:

"The LIN physical layer is in shutdown mode... the bus line is held in its recessive state by a high ohmic (330KOhm) resistor"


Regards,

iggi

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ikkishingu
Contributor II

Dear iggi,

I am sorry for delaying my reply a long time.

I have overlooked your response.

Is pull up resistor "not" selectable?

I think what you told would be as below,

LIN Control Register(LPCR) bit3 LPE:

0 : The LIN Physical Layer is in shutdown mode. None of the LIN Physical Layer functions are available, except

     that the bus line is held in its recessive state by a high ohmic (330kΩ) resistor. All registers are normally accessible.

So this description is only for shutdown mode.

On the other hand, we can select pullup resistor 330kΩ/34kΩ by setting/clearing LPPUE bit in my understanding.

If my understanding is correct, could you tell me the purpose of this selectable implementation?

Best Regards,

Ikki

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iggi
NXP Employee
NXP Employee

The 34K is the typical pull-up resistor on LIN module. The 330K pull-up option is used to decrease leakage current in shutdown mode and to decrease current consumption in standby mode.

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ikkishingu
Contributor II

Dear iggi,

Thank you!!

Ikki

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