So I have the following circuit, which is a bi-directional level converter:
I am using it to convert a 5v logic signal (which at high is actually 4.2v and low is ~0.2v) to a 3v3 logic signal. I have already tried my own, one directional level converter, like this:
simulate this circuit – Schematic created using CircuitLab
The problem is, when I use the one directional converter, the 5v input is connected directly (except for 3K Ohms of resistors) to ground, which causes the signal [from the 5v] to drop to 0v. Also, an LED on the board that the signal is coming from turns on. The board that I am using is this board and the output/signal I am using is the LB (Low Battery) pin, which is pulled to BAT, which is anywhere from 4.7v-3.2v, unless the battery drops below 3.2v, then LB drops to about 0.2v.
So my question is: Will the bi-directional converter have this problem? Will the input ever be connected directly to ground?
If so, how can I do this so that the 5v signal can be used as 3v3, I was thinking of using a MOSFET, where the base is the 5v from here.
How can I convert this ~4.7v signal (which is pretty much 5v logic even though it's really analog) to a 3v3 digital signal?
Finally, I am really REALLY dumb when it comes to circuitry, so try to dumb things down a lot please, thanks.
Best Answer
An open-drain/open-collector output is only pulled low and does not have a defined high level. Therefore, to get the desired high signal level, simply connect a pull-up resistor to that:
