8 Leds

[leonel]

Today I decided to use PIC16F57 because it´s cheaper than PIC16F872. PIC16F57 has a max. output current sourced/sunk by a single I/O port (PORTA, B or C) of 50 mA. If i use a 270R resistance from 5V, i´ll have 18mA that´s quite enough for my led brightness.
I wonder if ULN2003A or other component make my project "cleaner". If i only use the PIC16F57 i can trust in my project? In normal conditions I´ll not have problems?
My project it´s making a cooling machine, that has led´s to advise in what point of the machine goes.
Regards

[Bruce]

You'll have <18mA for each LED with a 270-ohm series limiting resistor at 5V.

LED current = Vcc - Vled/R. Vled is the voltage drop of the LED. R is the series limiting resistor.

With Vcc = 5V, Vled = 1.2V and R=270, then (5V-1.2V)/270 = ~14mA.

8 x 14mA = ~112mA total for 8 LED's. Should be fine. Most LED's will glow pretty good with just 8-10mA.

[BigWumpus]

You know, there are LEDs burning with 3mA ?
I think they will be better to connect directly to a PIC.