[SOLVED] OLED with SSD130X Driver and the different voltage levels

[Sudo_apt-get_install_yum]

Hi all!

So as a continuation on a project of mine I though of stick a cheap OLED on it to display some data. The OLED that I’ve been looking at use the SSD1305 or the SSD1306 driver and I’ll use them in I2C mode.

When looking at the displays datasheet and the technical datasheet for the SSD130X it says that it needs two voltages, one for the logic and one for the panel driving.

Logic voltage(VDD): 1.65V-3.3V
Panel voltage(VCC): 7V-15V

Here is the thing. When looking at complete modules on eBay that use a similar OLED and same driver I noticed that they don’t have any form of regulator to step up the voltage form the 3.3V to 7V-15V and they still work.

If I’m able to skip a second regulator for the panel driving I’d gladly do so, but what would the consequences be and how does it work?

Thanks for any help!

SSD1306: https://cdn-shop.adafruit.com/datasheets/SSD1306.pdf
SSD1305: https://cdn-shop.adafruit.com/datasheets/SSD1305.pdf

eBay module:

[oPossum]

It has a charge pump to provide the panel voltage.

Code: [Select]

2 Charge Pump Regulator
The internal regulator circuit in SSD1306 accompanying only 2 external capacitors can generate a
7.5V voltage supply, VCC, from a low voltage supply input, VBAT. The VCC is the voltage supply to the
OLED driver block. This is a switching capacitor regulator circuit, designed for handheld applications.
This regulator can be turned on/off by software command setting.

[ataradov]

Display controller has internal boost converter, all you need is to provide a few external storage caps.

[Sudo_apt-get_install_yum]

Thanks!
Where in the datasheet/ other documentation can I find this?

[ataradov]

oPossum provided a quote from the datasheet. There is also a typical schematic, which you can just copy 1:1.

[Sudo_apt-get_install_yum]

When looking through the datasheet of the SSD1305 I noticed that there was not mention of a charge pump regulator. So I assume that it’s a SSD1306 and higher exclusive?

Thanks for the help!

[oPossum]

It is an app note at the end of the SSD1306 data sheet you linked to. Looks like the SSD1305 does not have that feature.

[ataradov]

SSD1305 is also not used in any OLEDs commonly available on the market, so you don't have to worry about it.

Another controller you need to be aware of is SH1106, which is very similar to SSD1306, but has slightly different register set. Much better one, actually.

[Sudo_apt-get_install_yum]

A friend’s dad work in a company that creates panels and sells LCD, OLED and other types of screens for embedded computers. He mentioned that they had old stock with 128x64 OLED's with the SSD1305 and he could donate a few. That’s the only reason why it’s mentioned, but I could buy a few cheap OLED's from Digi Key or LCSC in wort case.

What’s the advantage of the SH1106? I could always wright a C driver for it, I can imagine that it wouldn’t be too different from a SSD1306 but that could just be wishful thinking

[ataradov]

He mentioned that they had old stock with 128x64 OLED's with the SSD1305 and he could donate a few.

It is really not worth the trouble unless he has a lot and you have a real project for them. If it is just a hobby, then buy anything based on SSD1306 and spare yourself a pain of building a charge pump.

What’s the advantage of the SH1106?

Just a better register set, a bit more thought went into its design. Pus you can actually read data out of the device in I2C mode. There is very little difference in programming them.

[Sudo_apt-get_install_yum]

Yeah this isn’t for production, it’s just hobby things but I’ll be making a dozen or so.
I really don’t like using the cheap eBay modules and using small wires to rats nest everything together, I prefer to make my PCB's and such.

So skip the SSD1305, aim for the SH1106 and settle with the SD1306 if the SH1106 isn’t available.

Thanks for the help!
Case closed!