| ??? 02/20/06 14:19 Read: times |
#110335 - Weak and very weak pull-ups Responding to: ???'s previous message |
Suresh said:
How could i know about the current and voltage being delivered by that weak pullup (pFET2). The internal active pull-ups are current sources. Their current depends on the potential you force at port pin by an external driver. The weak pull-up (PMOS-FET3) delivers up to 650µA - 50µA = 600µA in your example. Up to 50µA is delivered by the very weak pull-up (PMOS-FET2). Suresh said:
Also, if i need to bring it low with an external device (a switch), i think i dont need to worry about this transition current and voltage. Exactly, as Jan already mentioned. Kai |
| 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 |