For an OpAmp circuit, I want to create a small negative voltage to be able to reach 0V on the output.
While it's easy to invert e.g. a 3.3V supply with an ICL7660, MAX660 or some discrete charge pump circuit, this will end in e.g. -3.3V, where I just want -1V.
Problem is that most OPs are specified for 6V (Vdd-Vss), so if the positive supply is 5V, the negative supply most not be smaller -1V.
Using an OpAmp with a wider supply range limits the choices quite a bit and in my case would about twice the cost for slightly worse parameters (like offset voltage).
So I would prefer to get something like -0.5 to -1V from the negative supply. I yes, I know about phantom grounds and virtual grounds, but for the moment, I'd rather use a negative supply.
Now I could use e.g. a LM337 to get a voltage closer to-1V, but it's limited -1.25V. Just slightly out of nominal operation condition for e.g. an MCP607x , but still out.
Also e.g. the MAX660 doesn't work for input voltages smaller than 1.5V, so assuming no losses in the inverter, I can't get -1V by using a voltage regulator before the charge pump either.
I guess I could go on further by using a diode or a voltage divider with a voltage follower, but this seems like adding a hell of complexity for something as simply as a low current -1V supply.
So what would be the best practice approach to create -1V from e.g. a 5V supply (while keeping the 6V difference between 5V and -1V)?