In SSD1306 the segment current sets with resistor at IREF pin, and the current depends on VCC.
I have no stabile VCC, because it powered either directly from 9V alkaline battery or external 12V source, and I don't want create my own DC/DC or use internal charge pump (it too big consumption according the OLED's datasheet).
But I already has 3.3V stabile power source. So, can I use the following solution to create stabile IREF ~ 12.5μA (and therefore stabile brightness)?
And second question. Can I get any other trouble because of using not stabile VCC (but in the range from the SSD1306's datasheet)? VDD for logic is stabile 3.3V.