Even though 90% of the schematic was complete there was still 1 part which wasn't complete. I've been pushing it forward ever since I started on the GBA2. Today was the day; I put on some good music, got myself a cup of coffee and got to work. And...
well it didn't really go as planned, I think I wrote dozens of notes and possibly even more schematics. My Spotify playlist was already nearing the end of its 2nd round. Before I decided to quit the idea of a DDS/PWM driven Charge pump. It would just use too much space.
So aside from
- DDS/PWM driven Charge Pump
There were the other options:
- Just picking a random Step Up and hooking a simple charge pump inverter to it
- a SIMO ic (Single Inductor Multiple Ouputs)
- Make my own switching regulator and hooking a simple charge pump inverter to it
After reading the upper part of the log, you're probably wondering. 'What the heck was he trying to achieve?' good question, it's very simple. The 2 voltages specifically used by the original GBA LCDs. Hah! well if money grew on trees I wouldn't even have added support for it.
You probably went on a re-read, if you're actually interested at least or didn't quiet get the whole story.
So I had 3 options left, looking back at it. Well to be honest the 3rd one was never gonna work. Let's be honest.. So the 1st and 2nd were the ones I was deciding between in the end. I drew both schematic and PCB design.
and option 2
I liked both options, both used almost the same amount of space and both used parts that were easy to get my hands on. But well.. option 2 costed a bit more. The unit price of option 1 was €0,29 for the SU and €0,40 for the other parts. While option 2 the IC alone already costed €2.
So I decided to go with option 1 for the prototype, and if something were to go wrong with option 1; unstable voltage, noise, not being able to even reach the voltage etc. etc. Then I'll swap it with option 2 for the next revision