| ??? 07/01/09 14:58 Read: times Msg Score: +2 +1 Good Answer/Helpful +1 Informative |
#166622 - Concept seems fine... Responding to: ???'s previous message |
The circuit concept seems fine. Where the PNP solution as shown starts to fall apart is when the VCC level needed to source power into the relay ends up being higher than the VDD of the MCU. For example the mix of 12V relay supply and 5V MCU supply or the mix of a 5V relay driver and a 3.3V MCU. In both these cases a single PNP cannot be fully turned off by a high level MCU port pin in the circuit configuration.
Michael Karas |
| Topic | Author | Date |
| Relay control - 8051... | 01/01/70 00:00 | |
| looks good to me but ... | 01/01/70 00:00 | |
| Concept seems fine... | 01/01/70 00:00 | |
| re: relay control | 01/01/70 00:00 | |
| NPN and standard '51? | 01/01/70 00:00 | |
| standard 8051 | 01/01/70 00:00 | |
| Ye standard 8051 and the C8051Fxxx ... | 01/01/70 00:00 | |
| two times only... | 01/01/70 00:00 | |
| Relay Drive: Previously, on 8052.com | 01/01/70 00:00 | |
| 'ED2 is "biblical" as far as ports are concerned | 01/01/70 00:00 | |
| snubber | 01/01/70 00:00 | |
| At both needed! | 01/01/70 00:00 | |
| AC opener... | 01/01/70 00:00 | |
| 12V AC? | 01/01/70 00:00 | |
| yes... | 01/01/70 00:00 | |
| I would drive it by a DC source! | 01/01/70 00:00 | |
| Just have seen... | 01/01/70 00:00 | |
a little information | 01/01/70 00:00 |