Hi
I have attached a image I saw on the web. The transistor is used to drive a relay module by inverting the logic, which ensures that the relay PNP is switched off too.
Why is the 10K required pull down from base of transistor?
How is this value calculated?
If the input of the transistor (say from a GPIO) at 3.3V, is it because the micro I may float?
I thought that there would be a pull up internally on the micro side, so it can't be because of leakage current?
Can anyone help?
Thanks in advance
I have attached a image I saw on the web. The transistor is used to drive a relay module by inverting the logic, which ensures that the relay PNP is switched off too.
Why is the 10K required pull down from base of transistor?
How is this value calculated?
If the input of the transistor (say from a GPIO) at 3.3V, is it because the micro I may float?
I thought that there would be a pull up internally on the micro side, so it can't be because of leakage current?
Can anyone help?
Thanks in advance