| ??? 02/20/06 10:39 Read: times |
#110320 - maintaining low source impedence? Responding to: ???'s previous message |
Suresh said:
Logical 1 to 0 Transition Current(ITL) (Ports 1,2,3) = -650 µA 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 / 650µA = ca. 3kOhm. Otherwise the potential at port pin will never fall down to less than 2V, which is needed to detect logic low state. Kai Can i know how, the source impedence could be maintained low, so that the port pin could fall to logic low state. suresh. |
| Topic | Author | Date |
| AT89s52 Port pin clarifications: | 01/01/70 00:00 | |
| nice copy, where is the question | 01/01/70 00:00 | |
| output characteristics | 01/01/70 00:00 | |
| most confusing post | 01/01/70 00:00 | |
| Answers | 01/01/70 00:00 | |
| Logic 1 to 0 transition | 01/01/70 00:00 | |
| You haven't read the 'bible' chapter... | 01/01/70 00:00 | |
| no details about transition from logic 1 | 01/01/70 00:00 | |
| other way 'round | 01/01/70 00:00 | |
| There ARE!! | 01/01/70 00:00 | |
| pFET2 | 01/01/70 00:00 | |
| Weak and very weak pull-ups | 01/01/70 00:00 | |
| maintaining low source impedence? | 01/01/70 00:00 | |
| by making thje driver a sink............ | 01/01/70 00:00 | |
| Pull-downs create problems | 01/01/70 00:00 | |
| Maximum IOL per port pin: 10 mA ? | 01/01/70 00:00 | |
| IOL | 01/01/70 00:00 | |
| IOL = 10mA or 1.6mA? in port 1 | 01/01/70 00:00 | |
Depends on load | 01/01/70 00:00 |