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TRAVEO™ T2G

WoHa_955446
Contributor

Dears,

 

We are looking for the suitable required specification of External Crystal Oscillator for the stable implementation of Traveo II CAN communication 500kbps speed.

If you have, we would like you to give us your feedback.

 

Thanks and regards,

Kevin Han.

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1 Solution
Kavya
Moderator
Moderator

Hello Kevin,

 

We do not have one or a set of specific recommendations for External Crystal Oscillator for TVII device. It depends on the application's needs. However, below are some important considerations which might help you choose the right External Crystal Oscillator to support CAN FD communication in your application.

 

The max CAN clock tolerance should be +/-1.58% for baud rates up to 125kpbs and 0.5% for higher baud rates.

There are two major considerations in TVII to meet above CAN clock requirement:

1) Tolerance of External Crystal Oscillator you choose for TVII

2) Tolerance added by PLL which takes input from ECO and provides clock to CANFD peripheral block in TVII

 

When PLL output frequency and CAN FD speed are known, then the tolerance added by PLL circuitry in TVII can be estimated based on the clock jitter specifications given in the device datasheet. The maximum speed you can achieve with CAN FD in TVII is 8 Mbps. Even with the maximum CAN FD speed chosen, the  tolerance added by PLL is sufficiently less to achieve the CAN clock tolerance requirements.

 

OEMs may have even more stringent CAN clock requirement than 1.58% or 0.5%. The better approach to know what is the allowed maximum  External Crystal Oscillator tolerance is to:

i) Understand the max CAN FD clock to tolerance as per your requirements (these may be inputs from your customer or OEM)

ii) Know the required CAN FD speed (In your case it is 500kbps)

iii) Estimate PLL tolerance based on CAN FD speed, PLL output frequency and PLL jitter specifications given in the datasheet (We can help you estimate the PLL tolerance in TVII)

iv) The max tolerance of the External Crystal Oscillator that you can choose will be: max CAN FD clock tolerance - tolerance added by PLL

 

I hope the above explanation enables you choose the right crystal oscillator for your application requirements. If you want any further clarification, please feel free to post here.

 

Thanks,

Kavya

 

 

View solution in original post

2 Replies
Kavya
Moderator
Moderator

Hello Kevin,

 

We do not have one or a set of specific recommendations for External Crystal Oscillator for TVII device. It depends on the application's needs. However, below are some important considerations which might help you choose the right External Crystal Oscillator to support CAN FD communication in your application.

 

The max CAN clock tolerance should be +/-1.58% for baud rates up to 125kpbs and 0.5% for higher baud rates.

There are two major considerations in TVII to meet above CAN clock requirement:

1) Tolerance of External Crystal Oscillator you choose for TVII

2) Tolerance added by PLL which takes input from ECO and provides clock to CANFD peripheral block in TVII

 

When PLL output frequency and CAN FD speed are known, then the tolerance added by PLL circuitry in TVII can be estimated based on the clock jitter specifications given in the device datasheet. The maximum speed you can achieve with CAN FD in TVII is 8 Mbps. Even with the maximum CAN FD speed chosen, the  tolerance added by PLL is sufficiently less to achieve the CAN clock tolerance requirements.

 

OEMs may have even more stringent CAN clock requirement than 1.58% or 0.5%. The better approach to know what is the allowed maximum  External Crystal Oscillator tolerance is to:

i) Understand the max CAN FD clock to tolerance as per your requirements (these may be inputs from your customer or OEM)

ii) Know the required CAN FD speed (In your case it is 500kbps)

iii) Estimate PLL tolerance based on CAN FD speed, PLL output frequency and PLL jitter specifications given in the datasheet (We can help you estimate the PLL tolerance in TVII)

iv) The max tolerance of the External Crystal Oscillator that you can choose will be: max CAN FD clock tolerance - tolerance added by PLL

 

I hope the above explanation enables you choose the right crystal oscillator for your application requirements. If you want any further clarification, please feel free to post here.

 

Thanks,

Kavya

 

 

View solution in original post

WoHa_955446
Contributor

Hello Kavya. 

I really appreciate your feedback and it's very helpful  to take into account ECO for CAN.

 

Best regards, 

Kevin.