The final design has the 5V signal coming from elsewhere in the overall circuit. The power supply was just for testing but it provided the proper functioning, so I don't see a hugh issue with that. Am i missing something?
Yes. The power supply is not designed to perform like a TTL chip. It could be used , with an RC low pass filter (resistor and cap)
which results in a stable time controlled rising voltage with a time constant = RC = R X C , so 100k x 10uF = 1 Second. You can play around with the values to change the time constant but this circuit guarantees no "bounce" . A better solution would be a power on reset circuit (POR ) , which can be implemented with a simple 555 one shot timer or you could use a chip specifically designed as a power on reset like the MAX699CPA which delivers a negative (RESET-BAR ) pulse of from 140ms to 500ms duration on power up.
The advantage of this is that you are guaranteed a SINGLE NEGATIVE PULSE (NO MORE, NO LESS) where as with your dc power supply there could be hundreds of spikes or ringing or whatever. A 555 is very cheap. Here's a tutorial on the chip:
[ http://www.instructables.com/id/555-Timer/step2/555-Timer-Monostable-Mode/ ](http:// http://www.instructables.com/id/555-Timer/step2/555-Timer-Monostable-Mode/)
Here's another approach:
http://tradeofic.com/Circuit/4333-POWER_ON_RESET.html
http://ww1.microchip.com/downloads/en/DeviceDoc/31003a.pdf
The old school cheap power on reset circuit is the resistor cap I talked about . Resistor connected to the voltage input (in your case that would be the dc supply) and cap is connected to GND at one end and the other end of the resistor and cap are connected together to create the output signal where they are connected. The signal is a slowly (relatively ) rising voltage with
a curved shape to it . Here's an example of one:
MAX698-MAX699-107107.pdf (179 KB)
