Power Regulators (PC Engine LT)
The power circuit of the PC Engine LT consists of a few voltage rails, all stemming from the 9V input.
There are several paths the DC input takes. Initially it needs to become the 9V rail when only switched on.
The path to the switching regulator goes like so:
- 9V DC IN > X500 > + Diode - > Power Switch Middle Pin > 9V Switched
The 9V Switched rail is the output after the power switch is turned on.
In short the DC 9V comes in, goes through an inductor noise filter, then a diode (for reverse polarity protection), through the power switch (closest to inside middle pin) then out of the bottom right pin (when looking at the power switch from underneath), back up through the 1.25A fuse, and that forms the 9V Switched Rail.
The 9V switched rail fed into a switching step-down regulator with over-current protection. It steps the 9V down to approximately 6.5V.
This 6.5V output is then fed into the 5V LDO regulator. The 6.5V is the lowest the 5V regulator operates at so allows for minimal waste as heat.
The 9V from the DC jack also travels through the Matsushita TK1-6V.
This is a mechanical relay and switches the 9V DC power to the rest of the system when the
TODO: Finish where this relay circuit goes
