zlash
Newbie level 1
Hello!
I'm trying to teach myself some basic electronics and this is giving me several brain damage because of the little knowledge I have.
In most of the circuits involving an IC driving a LED, a resistor is usually used between the IC's output and the LED: The explanation given is that the resistor is needed to protect both the IC and the LED from becoming a nice puff of magic smoke. I can believe that this is true, but I really want to understand it.
After some research, I understand why a LED should not be connected directly to a power source: When the LED is operating it has a very small resistance so the current gets very high and it burns the LED.
The problem comes when an IC is added to the circuit, and I'll talk precisely about a PIC because its what concerns me.
Most PIC schematics I've seen don't use a resistor to power it making it seem that the PIC don't suffer the same fate as the LED when directly connected to a power source. This lead me to deduce that the PIC is offering some resistance. Immediately I went to this PIC's data sheet and found an "Unit Resistor Value" of 2k.
So, If the PIC is working as a 2k resistor, why do I need to use resistors at its outputs?
Thanks in advance, and sorry for my poor English.
I'm trying to teach myself some basic electronics and this is giving me several brain damage because of the little knowledge I have.
In most of the circuits involving an IC driving a LED, a resistor is usually used between the IC's output and the LED: The explanation given is that the resistor is needed to protect both the IC and the LED from becoming a nice puff of magic smoke. I can believe that this is true, but I really want to understand it.
After some research, I understand why a LED should not be connected directly to a power source: When the LED is operating it has a very small resistance so the current gets very high and it burns the LED.
The problem comes when an IC is added to the circuit, and I'll talk precisely about a PIC because its what concerns me.
Most PIC schematics I've seen don't use a resistor to power it making it seem that the PIC don't suffer the same fate as the LED when directly connected to a power source. This lead me to deduce that the PIC is offering some resistance. Immediately I went to this PIC's data sheet and found an "Unit Resistor Value" of 2k.
So, If the PIC is working as a 2k resistor, why do I need to use resistors at its outputs?
Thanks in advance, and sorry for my poor English.