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Suresh R
02/20/06 03:39
Read: 500 times

#110320 - maintaining low source impedence?
Responding to: Kai Klaas's previous message
Suresh said:

Logical 1 to 0 Transition Current(ITL) (Ports 1,2,3) = -650 A when VIN = 2V, VCC = 5V 10%
HOw this should be taken care of while connecting the driver circuit to the port.

Kai Klaas said:

This means, that if you want to force a port pin, which was programmed as input by writing '1s' into according SFR, to logic low, that you must take care that source impedance is not too high. Here, less than 2V / 650A = ca. 3kOhm. Otherwise the potential at port pin will never fall down to less than 2V, which is needed to detect logic low state.

Can i know how, the source impedence could be maintained low, so that the port pin could fall to logic low state.


List of 19 messages in thread
AT89s52 Port pin clarifications:      Suresh R      02/16/06 02:14      
   nice copy, where is the question      Erik Malund      02/16/06 06:30      
   output characteristics      Jan Waclawek      02/16/06 06:53      
      most confusing post      Jez Smith      02/16/06 07:34      
   Answers      Kai Klaas      02/16/06 10:35      
      Logic 1 to 0 transition      Suresh R      02/17/06 05:01      
         You haven't read the 'bible' chapter...      Kai Klaas      02/17/06 08:38      
            no details about transition from logic 1      Suresh R      02/18/06 03:27      
               other way 'round      Jan Waclawek      02/18/06 04:21      
               There ARE!!      Kai Klaas      02/18/06 06:54      
                  pFET2      Suresh R      02/19/06 07:29      
                     Weak and very weak pull-ups      Kai Klaas      02/20/06 07:19      
      maintaining low source impedence?      Suresh R      02/20/06 03:39      
         by making thje driver a sink............      Abhishek Singh      02/21/06 10:02      
         Pull-downs create problems      Kai Klaas      02/22/06 08:00      
            Maximum IOL per port pin: 10 mA ?      Suresh R      02/23/06 04:43      
               IOL      Kai Klaas      02/23/06 06:22      
                  IOL = 10mA or 1.6mA? in port 1      Suresh R      02/23/06 22:26      
                     Depends on load      Kai Klaas      02/25/06 07:40      

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