SN65C1168E: question of SN65C1168E spice model

Masaharu Takahashi

Expert 4170 points

Part Number: SN65C1168E

Hi, Team .

could you see below?

1. the spice model spec depends on the power supply and load ?

2.in order to get the more real result, should customer re-change the spice model internal spec ?

3.which sentence can customer change (which line should customer change in spice model)?

4.if customer assumes like below , how customer consider about cable for getting more real result ?

(should they write any spice information with cable impedance ? cable distance ?

<customer system+SN65C1168E> connected cable <Load>

5.if customer has to change the output impedance in spice model, does this mean that the I-V characteristic is non linearity ?

6.can you share I-V characteristic data ?

over 5 years ago

0 Hao L over 5 years ago

TI__Mastermind 25705 points

MASA-san,

These answers are based on my understanding about the model. We can confirm them with the modeling expert.

1) The model is dependent on Vcc and designed for 100Ohm load;

2) The customer could change the model to match their application;

3) I think it's the .SUBCKT DRIVER part;

4) Yes, the customer needs to have a model for the cable. Some spice tool has build-in models or some manufactures provide the parameters. Some custom models can be found in the reference.

www.edn.com/.../Improve-and-simplify-cable-simulation

http://www.ti.com/lit/ug/tiduei9/tiduei9.pdf

5) For each loading, the I-V is linear. But the internal impedance is not linear to the load.

6) What's the application? We can provide the I-V characteristic for your specific case.

Regards,

Hao

0 Masaharu Takahashi over 5 years ago in reply to Hao L

TI__Expert 4170 points

Hi, Hao-san

for 3) I think it's the .SUBCKT DRIVER part;

if customer changes the load, should customer change the value on SUBCKT DRIVER part? or any where customer should change ?

0 Hao L over 5 years ago in reply to Masaharu Takahashi

TI__Mastermind 25705 points

MASA-san,

Let me talk to the modeling expert first. I don't want to give you unverified answers.

Another option is that you ask your customer to specify their application. TI generates another model for that specific loading.

Regards,

Hao

0 Hao L over 5 years ago in reply to Hao L

TI__Mastermind 25705 points

MASA-san,

If your customer is confident about changing the model, it's OK to do so. The expected internal impedance of the device can be estimated with external load. Please let me know if it makes sense to you.

Regards,

Hao

0 Masaharu Takahashi over 5 years ago in reply to Hao L

TI__Expert 4170 points

Hi, Hao-san.

please see below

3) I think it's the .SUBCKT DRIVER part;

added Q: is there any example if load condition changes?

ex: if load is 〇〇ohm, how should they change in the sentence ?

6) What's the application? We can provide the I-V characteristic for your specific case.

Answer: application is servo amp and connected with Motor.

0 Hao L over 5 years ago in reply to Masaharu Takahashi

TI__Mastermind 25705 points

MASA-san,

The driver internal impedance can be estimated by the output voltage and the resistive load. For example, with Vcc=5V, the driver generates a 2V on a 100Ohm resistor. Then the driver's impedance is about (5V-2V)/2/(2V/100Ohm)=75Ohm.

As long as the resistive load, pull up/pull down, nodes on the bus are all modelled in simulation, you can use the result to compare with the lab data.

Regards,

Hao

0 Masaharu Takahashi over 5 years ago in reply to Hao L

TI__Expert 4170 points

Hi, Hao-san

when can you make the I-V data ?

my customer waits for it.

is there anything that i have to tell you ?

i believe that i had already addressed on your question on previous post like below.

6) What's the application? We can provide the I-V characteristic for your specific case.

Answer: application is servo amp and connected with Motor.

0 Hao L over 5 years ago in reply to Masaharu Takahashi

TI__Mastermind 25705 points

MASA-san,

I'm sorry I haven't started collecting the data. Can you provide the resistive load in the application?

Regards,

Hao

0 Masaharu Takahashi over 5 years ago in reply to Hao L

TI__Expert 4170 points

Hi, Hao-san.

thanks your reply.

that is 150ohm.

0 Hao L over 5 years ago in reply to Masaharu Takahashi

TI__Mastermind 25705 points

MASA-san,

I'll get the data for your soon.

Regards,

Hao

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SN65C1168E: question of SN65C1168E spice model