chrisspartan
New Member
Hi, my first post so please be gentle.
I am building a fuel gauge with a LM 3914 and have read the data sheet a number of times and read quite a few of the posts on here.
I understand basically how the LM 3914 works - what I dont understand is what voltage is applied across the LED's ie where LED V+ comes from? is it just the supply voltage V+ or is it an independant voltage source just for the LED's?
I understand the current through the LED's is controlled by 10 times current out of pin 7 but as I am planning to use standard 2.5V 20 mA 5mm LED's so I cannot work out how you apply the required 2.5V across the LED's.
I know I may be missing something fundamental but I don't get it?
Thanks
Chris
I am building a fuel gauge with a LM 3914 and have read the data sheet a number of times and read quite a few of the posts on here.
I understand basically how the LM 3914 works - what I dont understand is what voltage is applied across the LED's ie where LED V+ comes from? is it just the supply voltage V+ or is it an independant voltage source just for the LED's?
I understand the current through the LED's is controlled by 10 times current out of pin 7 but as I am planning to use standard 2.5V 20 mA 5mm LED's so I cannot work out how you apply the required 2.5V across the LED's.
I know I may be missing something fundamental but I don't get it?
Thanks
Chris