| ??? 02/09/14 17:00 Read: times Msg Score: +1 +1 Good Question |
#190268 - Interfacing 12V relay with AT89C51 |
1. I have to interface 12V relay & used circuit used is:
http://www.dnatechindia.com/Tutorial/...oller.html I have used R2=1K & R3=4.7K. Relay is operating fine but I have seen my pin gets loaded. Link says R2 can be avoided also. but i used for safety. When logic is +5V at AT89C51, due to loading voltage across it reduces to 1V or less. What should be correct values I should select. 2. I have to connect relays to PORT0 also. Now for using port0, first I needed external 10K sip after which I will connect the circuit. Is this correct?? Because I think this created two pull-ups across port0. One is 10K from sip & other is 4.7K(R3). Should I remove 10K sip from port0 in this case. 3. What should be max IOH & IOL for AT89C51. I was reading: http://www.atmel.com/images/doc0265.pdf On Page 10, maximum Iol per 8 bit port is 26mA(port 0) & 15mA other ports. What should be Ioh per port or per pin |
| Topic | Author | Date |
| Interfacing 12V relay with AT89C51 | 01/01/70 00:00 | |
| Mostly there | 01/01/70 00:00 | |
| Then what do to avoid loading?? | 01/01/70 00:00 | |
Pin doesn't pull up | 01/01/70 00:00 |