SN65C1168E: Is SN65C1168E's input impedance same as realistic situation and simulation situation?

Masaharu Takahashi

Expert 4170 points

Part Number: SN65C1168E

Hi, Team,

This is MASA.

Could you tell me below?

Is SN65C1168E's input impedance same as realistic situation and simulation situation?

the reason why I asked is below.

1 Customer had converted out SPICE model into LT spice to analysis.

2.in case customer changes its impedance as below shown. the result was same as actual measurement and simulation result.

・before

　　RYINT Y YINT 50

　RZINT Z ZINT 50

・after

　　RYINT Y YINT 18

　RZINT Z ZINT 18

so Customer asked me that "before" case is the realistic impedance and simulation impedance.

or should customer change the impedance accordingly ?

over 5 years ago

0 Hao L over 5 years ago

TI__Mastermind 25705 points

Hi, MASA-san,

The spice model is a pseudo model to mimic the device's IO behavior. Therefore 50Ohm is a simulation impedance. Your customer could change it the way they wanted. Please let me know if you have more questions.

Regards,

Hao

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

TI__Expert 4170 points

Hi, Hao-san

in that mean, 50ohm is more nearest impedance for actual IC. isn't it ?

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

TI__Mastermind 25705 points

MASA-san,

Actually the internal resistance could vary with the loading condition. For example, with 5V supply, the driver generates 2V on a 54Ohm load. Therefore the resistance of each side of the driver is about (5V-2V)/2/(2V/54Ohm)=40.5Ohm. If the driver generates 3V on a 100Ohm load, the equivalent resistance becomes (5V-3V)/2/(3V/100Ohm)=33.3Ohm. Please let me know if it makes sense to you.

Regards,

Hao

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SN65C1168E: Is SN65C1168E's input impedance same as realistic situation and simulation situation?