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Suresh R
02/16/06 02:14
Read: 3086 times
Chennai
India


 
#110130 - AT89s52 Port pin clarifications:
Hello Everyone,

I would like to check the correctness and also clarify on the details i have mentioned here regarding the port pins of AT89S52 for effective programming.

Initially all ports of AT89S52 are high.

1)a
VOL = Output Low Voltage (Ports 1,2,3) = 0.45 V at each pin
At this condition, sink current (IOL) = 1.6 mA at each pin

port pin in this mode is used to switch 'ON' a PNP Tr
example code: clr p1.x

1)b
VOL1 = Output Low Voltage(1) (Port 0, ALE, PSEN) = .45 V at each pin
At this condition Sink current (IOL) = 3.2 mA at each pin

port pin in this mode is used to switch 'ON' a PNP Tr
example code: clr p1.x

2)a
VOH = Output High Voltage (Ports 1,2,3, ALE, PSEN) at different source current ratings:
source current (IOH) = -60 A, VCC = 5V 10%. VOH = 2.4 V
source current (IOH) = -25 A VOH = 0.75 VCC
source current (IOH) = -10 A VOH = 0.9 VCC

Port pin in this mode is used to switch 'ON' NPN tr.
Eg code: setB p1.x

Doubt:
This shows different o/p high voltage rating. i need to know what does this signify in connecting a Transistor(NPN) to it.
Can this negative current drive the NPN transistors with presence of external pullups.


2)b
VOH1 Output High Voltage (Port 0 in External Bus Mode) at different source current ratings:
Source current (IOH) = -800 A, VCC = 5V 10% VOH = 2.4 V
Source current (IoH) = -300 A VOH = 0.75 VCC
Source current (IOH) = -80 A VOH = 0.9 VCC

same Doubt as in 2)a

3)
Logical 0 Input Current(IIL) (Ports 1,2,3) = -50 A when VIN = 0.45V
I would like to know what the above statement describes, having described the source and sink currents in 1 & 2.

4)
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.

Thanking you all,
-suresh.



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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