I need some tips selecting the right transistor to drive my 7 segment LED displays ( 3 of them )
http://www.lumex.com/specs/LDS-AA14RI.pdf
I am trying to adapt an existing circuit that I made by trial and error, and I am happy with, but I want a different micro controller and I want all surface mount ( except the LED ).
Right now my circuit drives the common anode with the emitter of a 2N3565 transistor with the base to a 100ohm resistor connected to the atmel 2313 IO pin. Collector tied to VCC. This is driving a smaller but older LED ( Kingbright SA08-21 ).
I want to do the same thing with an ATMEGA 8515
http://www.atmel.com/dyn/resources/prod_documents/2512S.pdf
I want to use a surface mount transistor, but I am having trouble figuring out what one to use and what value of resistor to use.
I also notice many circuits out there have resistors on the 7 segments as well. My circuit does not. Are these just current limiting? I may have discarded them because the display was not bright enough, is this OK, how can I make an educated decision.
http://www.lumex.com/specs/LDS-AA14RI.pdf
I am trying to adapt an existing circuit that I made by trial and error, and I am happy with, but I want a different micro controller and I want all surface mount ( except the LED ).
Right now my circuit drives the common anode with the emitter of a 2N3565 transistor with the base to a 100ohm resistor connected to the atmel 2313 IO pin. Collector tied to VCC. This is driving a smaller but older LED ( Kingbright SA08-21 ).
I want to do the same thing with an ATMEGA 8515
http://www.atmel.com/dyn/resources/prod_documents/2512S.pdf
I want to use a surface mount transistor, but I am having trouble figuring out what one to use and what value of resistor to use.
I also notice many circuits out there have resistors on the 7 segments as well. My circuit does not. Are these just current limiting? I may have discarded them because the display was not bright enough, is this OK, how can I make an educated decision.