I'm having trouble figuring out the name of this circuit.
It needs to delay turning "on" a 12V circuit and a 120VAC circuit, after a 5V circuit has been turned on.
Example:
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Turn on 1x power switch, which turns on a microcontroller (5V), a DC motor circuit (12V) and a large AC motor (120VAC).
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The sequence of switching "on" should be 5V, 12V, then 120VAC
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Without that sequence the 12V motors and 120VAC motor turn on wildly (for ~1 sec) as the microcontroller is "powering on".
Ideally a passive circuit.
Best Answer
You can use two or three power-on reset chips with different delay times. Here is one example of what I am talking about: TI LP3470.
http://www.ti.com/lit/ds/symlink/lp3470.pdf
There are other vendors and other chips with different features. On first application of power, these hold their reset output low, and keep it that way until after some delay time has expired, then they release it.
If you use three of them with different delays, you can get your three sequencing signals. You just need to work out the part where the release of reset causes your power rail to turn on. Let me know if you need help with that part. I suggest that you use a PFET to turn on 12V, and use the 12V to energize the coil of a relay for 120V.
I have one warning for you. With sequenced power come all sorts of potential problems. If there is any IO connection between 5V and 12V stuff, you should try to make sure that IO is held low by the 5V system until after the 12V system is powered on. Otherwise high current may flow from 5V IO into inputs of the 12V system (through power rail clamp diodes). If the 12V system is motors only, then I don't think there will be any problem.