| Michael Karas 07/01/09 09:58 Read: 249 times Beaverton Or USA Msg Score: +2 +1 Good Answer/Helpful +1 Informative |
#166622 - Concept seems fine... Responding to: Lukas Valecky'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... | Lukas Valecky | 07/01/09 07:35 |
| looks good to me but ... | Erik Malund | 07/01/09 07:58 |
Concept seems fine...  | Michael Karas | 07/01/09 09:58 |
| re: relay control | Andy Peters | 07/01/09 14:57 |
| NPN and standard '51? | Jan Waclawek | 07/01/09 15:03 |
| standard 8051 | Andy Peters | 07/01/09 16:32 |
| Ye standard 8051 and the C8051Fxxx ... | Michael Karas | 07/02/09 01:15 |
| two times only... | Steve M. Taylor | 07/02/09 02:40 |
| Relay Drive: Previously, on 8052.com | Andy Neil | 07/02/09 03:02 |
| 'ED2 is "biblical" as far as ports are concerned | Jan Waclawek | 07/02/09 03:04 |
| snubber | Lukas Valecky | 07/02/09 04:03 |
| At both needed! | Kai Klaas | 07/02/09 07:04 |
| AC opener... | Lukas Valecky | 07/02/09 07:22 |
| 12V AC? | Kai Klaas | 07/02/09 07:49 |
| yes... | Lukas Valecky | 07/02/09 08:22 |
| I would drive it by a DC source! | Kai Klaas | 07/02/09 08:32 |
| Just have seen... | Kai Klaas | 07/02/09 16:01 |
a little information | Lukas Valecky | 07/03/09 01:36 |