| ??? 02/28/10 21:56 Read: times |
#173656 - Barbecue time... Responding to: ???'s previous message |
Sv said:
Is it safe to connect the output pin of LM339 the uC directly? There's a certain chance damaging the micro, when the port output is emitting high level while the LM339 is emitting low level. In my designs I have current limiting resistor of about 330R in series to the port pin. But maybe I'm too paranoid... Sv said:
LM339 has open collector at outputs and uC has internal pull-ups They are too weak to properly pull-high the input when the application is in a noisy ambient. Add a 10k pull-up. There are nice single-in-line resistor arrays on the market to acomplish this. Sv said:
And last yr, i had put it in reverse polarity once by mistake. I still remember, the microcontroller got heated up so quickly when i did that.
Could that be the cause? Of course, it could! A microcontroller isn't desined to withstand such a barbecue! Sv said:
And by the way, is there any improvements in the new pieces by NXP? In that you need not turn on your brain any longer, when plugging the micro into the socket?? Kai Klaas |
| Topic | Author | Date |
| Internal Pull-Up in P89V51RD2BN ? | 01/01/70 00:00 | |
Barbecue time... | 01/01/70 00:00 |