1. I have to interface 12V relay & used circuit attached.
I have used R2=1K & R3=4.7K. Relay is operating fine but I have seen my pin gets loaded.
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
I have used R2=1K & R3=4.7K. Relay is operating fine but I have seen my pin gets loaded.
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