SparkFun Forums

[JonChandler]

What chip are you using for the backlight invertor on the Graphical LCD Carrier Board? I'm working on my design to use it and haven't found anything that looks like a great choice.

Thanks

[riden]

If you are looking for an inverter to drive an EL panel, I've used the Durel 355B device. The QFN package requires ZERO external componets as it has the inductor built into the tiny package.

http://www.rogerscorporation.com/durel/ ... 052A03.pdf

[JonChandler]

Wow, that looks like a winner! Couldn't be any easier. I think this will work well in my design.

Thanks,

Jon

[riden]

It does the job quite nicely.

Just remember that the version having the built in inductor is a QFN package. I glued my chip upside down to the back of the LCD and carefully soldered the connections dead-bug style. Better fabricators than I would have designed a PC board and properly attached the device to it!

[sparky]

We use the HV826MG.

Unfortunately Rogers doesn't answer their phone. I'll try again later today.

-Nathan

[jradomski]

If you are looking for an inverter to drive an EL panel, I've used the Durel 355B device. The QFN package requires ZERO external componets as it has the inductor built into the tiny package.

http://www.rogerscorporation.com/durel/ ... 052A03.pdf

have you tried that chip with the crystal fontz displays.. the frequency listed is lower than the spec..

[jradomski]

We use the HV826MG.

Unfortunately Rogers doesn't answer their phone. I'll try again later today.

-Nathan

I am assuming thats from supertex am I correct??

[riden]

have you tried that chip with the crystal fontz displays.. the frequency listed is lower than the spec..

I've used the Durel chip with other LCDs (2x20, 4x20, etc.) but not with the CrystalFontz display. All of my CrystalFontz units have LED backlights.

You are correct that the CrystalFontz specs want a frequency of 400-1000 HZ and the Durel device delivers 170-300 HZ (240 HZ typical) and the Supertex device 300-450 HZ (375 HZ typical) which puts the Durel device below spec and the Supertex chip on the low end or slightly below spec.

The CrystalFontz unit also seem to want a EL driver voltage between 78-85 volts RMS but both the Durel and Supertex chips deliver a minimum of 120 RMS (Durel) and 106 RMS (Supertex) so both chips seem to be above the CrystalFontz spec.

The drive frequency and voltage contribute to intensity and backlight life and are affected by the reactance of the actual display being used.

From a hobbiest point-of-view, I doubt that it makes a whole lot of difference using either chip, even though both are technically out-of-spec for the CrystalFontz display.

Disclaimer: The previous paragraph is true for the personal projects that I build and your mileage may vary. If I were building a commercial product, I would want to look deeper and see what, if any, consequences there are using these chips with the CrystalFontz display.