Can somebody help me understand what the difference between a positive and negative voltage regulator is ?
Does it mean that the output is with respect to VDD or VSS ?
And if it is with respect to VDD is the output device a pmos?
and if it is with respect to VSS, the output device is a nmos?
Can somebody help me understand what the difference between a positive and negative voltage regulator is ?
Does it mean that the output is with respect to VDD or VSS ?
And if it is with respect to VDD is the output device a pmos?
and if it is with respect to VSS, the output device is a nmos?
Instead of going through a long explanation, please note:
Trying to generalize is not the way. Consider them separately and case by case.
Take the positive first and consider that whatever voltage is mentioned, it is referred to common / ground. That is the basic way to reference voltages. Otherwise, the description will explicitly say so (as in the case of internal reference voltages that could / could be not referred to ground). LM317 and MIC29152 have a difference here.
The topology used for an specific regulator does not repeat in others doing the same even if they are positive (or negative ones). Datasheets use to bring simplified schematics showing how they work.
thank you atferrari for your reply.
suppose there is no explicit description, looking at any schematic,
how will I know if a certain voltage is referenced to VDDA or VSSA?
Assuming you mean a negative supply where a positive supply is present as well...
This is one of those instances where it helps when we can see the current direction through the wires. So I made a simulation showing the simplest configuration.
The link below will open the animated simulator at falstad.com/circuit, load my schematic (below), and run it on your computer. (Click Allow to load the Java applet.)
thank you atferrari for your reply.
suppose there is no explicit description, looking at any schematic,
how will I know if a certain voltage is referenced to VDDA or VSSA?