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???
12/17/07 18:49
Modified:
  12/17/07 18:51
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 		 #148401 - No, isnt needed
Responding to: ???'s previous message
Mehdi said:
At spec 2 we have:
At logic "0", in the transmitting state, the device shall have an equivalent sink resistance of not more than 110 ohm between TX_RX and ground. in your mind 100 ohm res isn't needed between drain and k-line?

No, such a resistor isn't needed. Have also a look at the datasheet of Si9241AEY

http://www.vishay.com/docs/70787/70787.pdf

In the last picture "application circuit" you can see that the diagnostic tester pulls down the ISO K-line by 0.4Ohm. So, a 100Ohm resistance isn't needed.

The BS170 shows an impedance of about 5Ohm, when turned-on by a gate source voltage of 5V. The impedance is only critical, if it becomes too high, because then it's more difficult to generate a proper "0" signal.

Kai


List of 56 messages in thread
TopicAuthorDate
I/O Electrical Specification            01/01/70 00:00      
   have a look at J1708            01/01/70 00:00      
      J1708 INTERFACE CIRCUIT            01/01/70 00:00      
         naah            01/01/70 00:00      
   an I/O compatibility.            01/01/70 00:00      
      an I/O compatibility            01/01/70 00:00      
   fet+resistor for TX, resistor + comparator RX            01/01/70 00:00      
      more clarification!            01/01/70 00:00      
         What is the effective communication distance            01/01/70 00:00      
            about 1 meter!            01/01/70 00:00      
               NO, that would be wrong if multimaster            01/01/70 00:00      
                  master and slave            01/01/70 00:00      
                  But we already know what we are Transmitting            01/01/70 00:00      
         more clarification needed            01/01/70 00:00      
            more clarification needed            01/01/70 00:00      
      J1708 Problems            01/01/70 00:00      
         Confusing A-line and B-line in a plug?            01/01/70 00:00      
         90% of J1708 devices            01/01/70 00:00      
   Please tell us which chip you use!            01/01/70 00:00      
      i must simulate ECU behavior,not a single chip            01/01/70 00:00      
         what is the bit rate and will this do            01/01/70 00:00      
            5 bps!            01/01/70 00:00      
               it will make the output 110 ohms            01/01/70 00:00      
                  a positive to you erik.            01/01/70 00:00      
                  DG211?            01/01/70 00:00      
                     you need an analog switch            01/01/70 00:00      
                        4066 /DG211?            01/01/70 00:00      
                           Use an analog Multiplexer instead eg ADG509A            01/01/70 00:00      
   Final Scheme,Any Advice?            01/01/70 00:00      
      some            01/01/70 00:00      
         A positive to you Stefan,            01/01/70 00:00      
         IRF7303            01/01/70 00:00      
         SW1            01/01/70 00:00      
      Link and circuit...            01/01/70 00:00      
         3 Positive to you Kai,            01/01/70 00:00      
         what happens on RX when in+>in-            01/01/70 00:00      
            LM393 is comparator with open collector output            01/01/70 00:00      
               Ok,            01/01/70 00:00      
         some question!            01/01/70 00:00      
            Answers            01/01/70 00:00      
               Tahnks Kai for you valuable time,            01/01/70 00:00      
         thanks again but            01/01/70 00:00      
            No, isnt needed            01/01/70 00:00      
               Thanks            01/01/70 00:00      
               Thanks            01/01/70 00:00      
         Link and circuit...            01/01/70 00:00      
             Link and circuit            01/01/70 00:00      
            Please read "Functional Description" of datasheet            01/01/70 00:00      
               Mehdi why you want to invent the wheel??            01/01/70 00:00      
                  Mehdi why you want to invent the wheel??            01/01/70 00:00      
   no offense, but I think you are off the rocker            01/01/70 00:00      
      lower depth of knoledghe            01/01/70 00:00      
      Its known as progressive evolution            01/01/70 00:00      
      So, you blindly guessed...            01/01/70 00:00      
         what is an ECU?            01/01/70 00:00      
            Engine Control Unit            01/01/70 00:00      

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