Quick ? about this uln2803
can i just use it as a replcement for normal transistor.
Like in the schem..
most i think is the pin 10, is that commond ground for all transistors ?

 

As long as you realize that the innards are more complicated than a transistor:



Pin 9 is E (gnd). Pin10 is COM (used as a snubber for inductive loads)

 

Bi-polar Darlington configuration, fairly high impedance input.
Max.

 

Bi-polar Darlington configuration, fairly high impedance input.
Max.

Don't forget those devilish little details - you need double the Vbe to turn them on, and you can't saturate a Darlington.

 

Quick ? about this uln2803
can i just use it as a replcement for normal transistor.
Like in the schem..
most i think is the pin 10, is that commond ground for all transistors ?

It depends on how you intend to use it. Post description and/or schematic please?

eT

 

When you using bjt as a driver then maybe you can using uln2803 to replace it.

The uln2803 provided the collector-current rating of each Darlington pair is 500 mA, and also the total current is the same, in most situations that you just using the current less then I = 500 mA * (1/3) = 166.67mA, whatever each or total, the better way is to using the total current as I = 500 mA * (1/5) = 100 mA for the heat issue, what is the best balance point for the current and heat, when the IC can be touch with fingers and it just has a little warm, but not hot.

 

foforgot the Picture. just think of 5 volt as TTL output

 

Do not ground pin 10. Either tie it to +5V, or let it float.

 

You can see the practical application as below, uln2003 is the same as uln2803 just less one driver, you can let the inputs floating or connected to ground, the common pin of diode can be float or connect to +5V, when the load is relay or coil must be connected to +5V.