how to make a -10V supply...

[kit_714]

Hi all,

i am currently playing the interface between MCU and 128x64 Graphical LCD. However, i need to provide -5V and -10V for two pins of the LCD module.

I would like to ask...How can i provide those -ve voltage?

Remark that i only got a +5V supply on the whole circuit.

Thanks in advanced.

Kit

 

[Old Nick]

https://www.farnell.com/datasheets/85749.pdf

https://www.farnell.com/datasheets/63380.pdf

 

[banjo]

Most LCD require very little current on the negative voltage bias supplies. These are usually supplied by charge pump ICs. The produce a negative voltage by using capacitors and internal switches. First the cap is charged to your positive rail, then internal switches reverse the leads on the cap and connect the positive to ground.

Take a look at MAX864 for an example chip.

Also,

https://en.wikipedia.org/wiki/Charge_pump

has a detailed description.

 

[kit_714]

Hi All,

Thanks!

However, is there any ICs have 2 outputs having -5V and -10V?

Although i can use potential divider on -10V sourve to create -5V source...
it would be better if such IC would exist...

Thanks in advanced first....

 

[Old Nick]

Hi All,

Thanks!

However, is there any ICs have 2 outputs having -5V and -10V?

Although i can use potential divider on -10V sourve to create -5V source...
it would be better if such IC would exist...

Thanks in advanced first....

You can't use a voltage divider to create a -5V power supply from a -10V, (if you want to know why I can explain).

I doubt you'll find a chip with the 2 outputs your looking for.

If you look at my previous post, 2 chips there give you both voltages. If you need to use less space then you'll can use surface mount components

 

[xorcise]

Most KS0108 128x64 GLCD's already have the LCD display voltage converter on-board. It's the Vee pin. Run this voltage through a small pot to the Vo pin and you have all you need.

**broken link removed**
**broken link removed**