| ??? 11/28/08 13:58 Read: times |
#160366 - the thing in the datasheet everybody misses Responding to: ???'s previous message |
But even then, if there are high currents sinked into other ports at the same time, then the internal ground on die can be lifted by some hundreds of mV, leading you to believe that your port output shows a wrong VOL. Make no mistake, if this is the case, i.e., if into another port(s) such a high current is sinked, that your port can no longer emit regular TTL levels, then this current is way too high and you must change your design.
any complete datasheet for a '51 will have a "maximum total current for all ports" (verbiage may differ) exceeding that one can also be the cause. Erik |
| Topic | Author | Date |
| ouput voltage when pin is pulled low | 01/01/70 00:00 | |
| Check the datasheet | 01/01/70 00:00 | |
| Different VOLs? | 01/01/70 00:00 | |
| Why not? | 01/01/70 00:00 | |
| Always variances | 01/01/70 00:00 | |
| Shouldn't be that different! | 01/01/70 00:00 | |
| the thing in the datasheet everybody misses | 01/01/70 00:00 | |
| Within limits but.. | 01/01/70 00:00 | |
| AT 25 mA!!! | 01/01/70 00:00 | |
| Average | 01/01/70 00:00 | |
| Not modulating the pin! | 01/01/70 00:00 | |
| ...any low is a fine low! | 01/01/70 00:00 | |
| 'some' may not be a problem .... | 01/01/70 00:00 | |
| Of course, but... | 01/01/70 00:00 | |
| No, it is not fine! | 01/01/70 00:00 | |
no, it is not | 01/01/70 00:00 |