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Kai Klaas
02/18/06 06:54
Modified:
  02/18/06 06:57

Read: 587 times
Germany


 
#110269 - There ARE!!
Responding to: Suresh R's previous message
Suresh said:
i went through the Bible (Chapter - Hardware Description) but couldn't find enough description regarding the transient conditions (from logic 1 to 0)in port(1,2,3).

THERE ARE ENOUGH DETAILS, but you must also think a bit!!
Read the chapters "Writing to a Port", "Port Loading and Interfacing" and have a look at figure 5 of this 'bible' chapter:

http://www.semiconductors.philips.com/acrobat_d...WARE_1.pdf

Think about what happens, if the input inverter skips, when input voltage sinks to less than about 2V. Which pull-up turns-off then? Which pull-up still delivers current? Why does the current flowing out of the port pin decreases from about 650ľA to only about 50ľA?

Supporting questions: What potential needs a PMOS-FET at gate to turn-on? What needs a NMOS-FET?

Kai

List of 19 messages in thread
TopicAuthorDate
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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