I understand what a pull-up resistor is for, when it is needed, and why they are important, but I am a little shakey on the theory behind how they work (my Analog skills are a little on the low side). Can anyone share a good explanation?
The load, whatever it is, requires a positive current (current into the load) in order for the voltage to rise. The pullup resistor provides that current. I=V/R as always. The open collector is able to sink current and pull the voltage down.
It depends entirely on the load - think of the open-collector output as a simple switch, it can be on or off - when it's off it's as if it's not there at all. The pull up resistor has to provide enough current for whatever it's feeding - one example would be an LED, the open-collector gate is connected across the LED (which goes to ground), the top of the LED goes to +ve via a resistor as normal. When the gate is turned off the LED lights, as usual, fed from it's current limiting resistor - when the gate is turned on, it bypasses the current round the LED, extinguishing it.
I would like to point out that M means milli as in .001. There is probably no confusion in this case, but another could be confusing. Megohm has to be spelled out as in 1Meg.
I would like to point out that M means milli as in .001. There is probably no confusion in this case, but another could be confusing. Megohm has to be spelled out as in 1Meg.
whats really annoying is when I found a capacitor that had an M for micro. Imagine my disappointment when I discovered that my newly found 100 megafarad cap was a measly .1 milli I coulda been rich...
whats really annoying is when I found a capacitor that had an M for micro. Imagine my disappointment when I discovered that my newly found 100 megafarad cap was a measly .1 milli I coulda been rich...