[SOLVED] -20V display Bias voltage

[TechGuy]

Hello, has anyone any idea how to generate -20V bias voltage for a display format 240x128 ?
what chip should I use! and and if any one has used any circuitry already tested that works..

thanks,

 

[BradtheRad]

I imagine someone can recommend an IC containing a boost converter. It is a switched-coil converter which inverts the polarity of the power supply.

If you only need a tiny amount of current, there is the voltage multiplier. It is easily made from a 555 IC, plus a sufficient number of Villard stages.



The 3 ohm resistor is not needed. It is only there to signify some amount of impedance in the 555's output.

 

[TechGuy]

Thanks for your reply mate much appreciated, unfortunately i need more current! is any way to boost the current in that circuitry? though I was after a inverting switching regulator chip...

Cheers

 

[erikl]

i need more current!

You didn't reveal your input voltage nor your output current requirement! You want us to guess?
Perhaps this one could do the job. S. fig. 10

 

[TechGuy]

You want us to guess?

You are right! I should have add more info, Input between 5 to 15V and output max -25V I Max is the only thing I'm not sure about. I think the mc34063 will definitely do the job!
thank you for your help.