Email: Password: Remember Me | Create Account (Free)

Back to Subject List

Old thread has been locked -- no new posts accepted in this thread
???
02/26/08 13:53
Read: times


 		 #151486 - 80uA is not a maximum specification
Responding to: ???'s previous message
The 80uA specification is the maximum that the chip will provide as a pullup. That does not mean that you must limit the input current to 80 uA.

You have to provide no more than 660uA to force the pin to a zero level. Your sensor could do this easily, since you are already putting 10 mA into R4.

List of 40 messages in thread
TopicAuthorDate
P3.5 input problem            01/01/70 00:00      
   100k is way too large            01/01/70 00:00      
      Yup            01/01/70 00:00      
      ports1-3 vs. port0            01/01/70 00:00      
      a small correction            01/01/70 00:00      
   Page 4 datasheet says            01/01/70 00:00      
      Calculating the maximum resistor            01/01/70 00:00      
         Calculating the ...            01/01/70 00:00      
   80uA is not a maximum specification            01/01/70 00:00      
      re:resistor            01/01/70 00:00      
   Resistor            01/01/70 00:00      
      I would not            01/01/70 00:00      
         Resistor            01/01/70 00:00      
            Resistor ... again ...            01/01/70 00:00      
      basic troubleshooting first            01/01/70 00:00      
         the sensor and its application            01/01/70 00:00      
            Oh, max frequency is ~4kHz :-)            01/01/70 00:00      
         Please ignore the "basic troubleshooting"            01/01/70 00:00      
         pray tell why            01/01/70 00:00      
            Capacitance problems ...            01/01/70 00:00      
   You have totally misunderstood the situation            01/01/70 00:00      
      thank you Kai            01/01/70 00:00      
         maybe it is            01/01/70 00:00      
            Link in original post            01/01/70 00:00      
            datasheet            01/01/70 00:00      
         Being paranoid is a good attitude...            01/01/70 00:00      
            Paranoia medicine            01/01/70 00:00      
               Yes, perfect, i also thought about this...            01/01/70 00:00      
                  the "industrial strength" 485 transciever            01/01/70 00:00      
                     But they gaurantee this            01/01/70 00:00      
      But the micro port shouldn't be driving anything            01/01/70 00:00      
         Missing the boat.            01/01/70 00:00      
            Waving at the boat.....            01/01/70 00:00      
               wrong place (in some instances)            01/01/70 00:00      
            More about the P3.5 pull-up issue            01/01/70 00:00      
               one simple way            01/01/70 00:00      
               AT89S8252            01/01/70 00:00      
         Please read this...            01/01/70 00:00      
   ABS & Safety            01/01/70 00:00      
      safety concerns            01/01/70 00:00      

Back to Subject List