As many have noticed, I’ve stopped offering my Simple iPad LCD Adapter for sale. The reason I’ve given is that I am working on an improved version of the board. Well, as of today I’ve gotten far enough on the design that I’d like to share it.
The most drastic change for this design is the integration of buck and boost power supplies to drive the panel and backlight respectively. I was not happy with telling people they’d need to provide their own regulated power – the panel isn’t THAT sensitive to voltage wobble, but it can be a problem with particularly long power leads, despite the large hold-up capacitor. Now the board should be able to take between 5 and 18 volts and spit out well-regulated rails.
Several other things have changed as well. I’ve changed the full-size DisplayPort connector to a miniDP connector, because for as small as the board is, the full-size connector was a waste of space. I’ve added a proper connector for power – while handing out boards with bare wires soldered on was functionally workable, it’s not exactly as clean a solution as I prefer. There is no longer a diode OR between external and DisplayPort power, because cables that carry DP_PWR are so uncommon that it is unnecessary. And there’s a fuse, to limit catastrophic failure in the event of a solder bridge or improper installation.
Now, the added components will increase BOM cost – I’m not sure by how much, but I know it will. However, I have designed in jumpers that will allow users who still want to feed in their own 3.3V and who don’t need a backlight supply to use this board in the same way as the old one. Hopefully this will make the design more accessible to people who want a more compact, all in one design without alienating those who like it how it was.
The design is a day or two from completion. As per typical, I’ll be building a board up and debugging it before I release the design documents, so that I don’t release something that won’t work. So keep an eye out in the coming weeks.