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Densitron OLED Display question

KennyMillar

Hi

 

I'm designing a product which contains a DENSITRON DD12864YO-3A OLED display.

 

This display requires separate supplies for Logic  and Display

The logic supply is called VDD, and the Display supply is called VCC

 

And the datasheet says this about the VCC supply : This is the most positive voltage supply pin of the chip. It can be supplied externally or generated internally using internal DC/DC voltage convertor.

 

However, the data sheet does not mention how to enable the built in DC/DC convertor or how to select it.

 

Does anyone know how to enable the built in DC/DC for VCC on this device? Do I just leave PIN 23 (VCC) Floating and the device just knows to switch on the internal DC/DC?

 

The DD12864YO-3A display uses a solomon systech SSD1305 controller.

 

Thanks in advance!

 

-Kenny

  • Hi Kenny,

     

    I had a quick look at the datasheet. Sometimes the Densitron displays are difficult to understand due to conversion to English. Looking at the power up and down sequence it would appear that you have to provide the +12.5V VCC supply and you will have to arrange for this to be switched ON and OFF under micro control as it shows that the VDD is powered first, then initialisation and then finally VCC supply on. All quite simple with your micro interface but a little bit of additional hardware to generate the VCC. By the way, this is quite low current so you could generate this with a step up regulator like the Linear Tech LTC3127 which can generate the +12.5V from the 3.3V of the display VDD.

     

    I would also suggest you contact Densitron with your query just to confirm. I have found the UK support to be very good in the past.

     

    Good luck

    Dave...

  • in reply to DaveMcLaughlin

    Hi Dave

     

    Thanks for the reply, and that was the conclusion I came to at first too, which was why I was confused about the reference to internal dc/dc.

     

    However - that module contains an SSD1305 controller, and in the the data sheet for that there is a command to turn on the internal DC/DC convertor :-)

    That also allows me to conform to the start up sequence by bringing up the logic fisrt, and switching on the DC/DC at the appropriate time.

     

    Thanks again,

    -Kenny

  • in reply to KennyMillar

    Excellent. Well found. I didn't actually check for the SSD1305 datasheet.

     

    Have you gotten drivers for this display? I looked around and the best I could find was from Ramtex. I have used their colour TFT drivers and they are so simple to get going andyou get the source code. Not cheap but time is money for some projects unless your's is a hobby job?

     

     

    Good luck with the project.

     

    Dave...

  • in reply to DaveMcLaughlin

    Thanks Dave,

     

    The main micro in this product is a PIC18F46K20-E/PPIC18F46K20-E/P, and thankfully Microchip have a basic set of drivers for this device.

    I only need text and a few primitives like lines and so on, so I don't need a full gui-driver set just now.

     

    The project isn't a hobby project it's part of a full commercial product, but the customer wants everything yesterday as usual.

     

    -K

  • I've used OLEDs before and come across the same issue... on-board DC-DC converter, however no clear information about the feature.

     

    When I did look into the option, it presented as a bad solution.  Having a buck switcher located a great distance from the schotty and inductor is a bad recipe. Particularly for emissions.  You are better off having a small low current buck converter to do the job, like a TPS61041DBVR.  This gives you the option to set the voltage to the display (which can be OLED colour dependant) as well as have the important on/off control to enable correct startup/shutdown procedures.