SN65HVDA100-Q1 and a K-LINE standard

Masami-san,

I moved this thread to the appropriate forum to be answered.

BR,

Frank

Thanks Frank for moving the thread.

Masami-san,

The ISO9141 standard for K-line existed before the LIN standard was created, and the physical layer for the LIN standard was based on this. The major difference between the LIN standards and the n K-Line (ISO 9141 and ISO14230 with the data link layer) standard is that the slave nodes usually have a high impedance pull up resistor >200kΩ in K-line, but have a much stronger pull-up resistor in LIN. LIN transceivers have a built in pull-up resistance on the order of 20-60kΩ. 

Also, the LIN standard specifies data rates from 1kbps to 20kbps, whereas K-Line can go as low as a few bits per second. Therefore, most of the LIN transceivers we sell have a feature called dominant state timeout on them so that the bus cannot get permanently stuck dominant in the case of a fault. If you plan to be using data rates lower than 1KBPS, I would recommend looking at the SN65HVDA195-Q1 which does not have this dominant state timeout feature.

Thanks,

John

John-san and Frank-san,

Thank you for your reply.
I answer it to the customer.

Thanks, Masami M.

Hi, John-san

Please let me know by addition.
When a circuit configuration is a master node, it is indicated for the example of a circuit (datasheet P14 Figure 8.) which appears in the datasheet of SN65HVDA195-Q1 that the pull-up resistor and diode of 1kOhm are indispensable.
Are the pull-up resistor and diode of 1kOhm indispensable in regulation of ISO9141 (K-Line)?
Does connecting with the same part have indispensable pull-up resistor and diode of 200kOhm in the case of a slave node?

Thanks, Masami M.

Hi Michino-san,

The ISO9141 standard outlines two types of node, the diagnostic tester (master) and ECU (slaves). The master node is required to have a pull-up resistance of 510Ω for a 12 volts system for a logic "1" state, and have a pull-down strength capable of making the output less than 10% of the supply voltage with a maximum sink current of 2A (the resistance is not specified for the pull down strength).

The slave nodes are stated to act as a resistance to ground of at least 5kΩ*N, where N is the number of nodes on the network. This ensures that the overall pull-down strength on the bus does not get too strong.

Therefore, an external resistor should be placed on the master node so that the pull-up strength is stronger than the typical 20-60kΩ.

Thanks,

John

Hi, John-san

Thank you for your reply.
I understood this resistance.
Please let me know one more in a master node.
Is the diode connected to resistance in series needed in regulation of ISO9141 (K-Line)?

Thanks, Masami M.

Hi Masami-san,

The purpose of the diode is to block any positively going transient on the LIN or K-Line bus from getting onto the supply pin. I would recommend using a diode as well.

Thanks,

John

Hi, John-san

Thank you for your reply.
I understood the necessity for a diode.
Please let me know whether finally it is written to the regulation document of ISO9141 (K-Line) that a diode is required.
'LIN Specification Package Revision 2.1' is indicated to be 'The serial diode is mandatory.' in the clause of 6.5.4 at the portions of Rmaster and Rslave.

Thanks, Masami M.

Hi Masami-san,

I only have the 1st edition of the ISO 9141-1 standard (dated 1989). Looking at http://www.iso.org/ it looks like a -2 version was published 5 years later (in 1994) that I do not have. With that being said, I just went through the -1 version that I have and there are no requirements for a diode.

Please let me know if you have any other questions,

John

Hi, John-san

Thank you for your reply.
I answer it to the customer.

Thanks, Masami M.