How to generate Negative powser supply from +5V ?

[octal]

Hi,
I would like to use a controller-less LCD. I have to supply (-19V) (negative power) to LCD controller. How can I generate it ? my circuits is powered by +5V regulated supply (I'm using a PIC microcontroller).

Best regards

 

[Nigel Goodwin]

Easy answer! - DON'T use a controllerless LCD, it's far too much work for too little gain.

But to get -19V it would be easiest to get it from the transformer if it's a mains project, for a battery project either an inverter and transformer, or inverter and voltage multiplier (assuming current requirements are low).

Depending on the PIC, you may even be able to use it's PWM module to generate a suitable voltage, check how the PICKit1 generates Vpp.

 

[octal]

Easy answer! - DON'T use a controllerless LCD, it's far too much work for too little gain.

But to get -19V it would be easiest to get it from the transformer if it's a mains project, for a battery project either an inverter and transformer, or inverter and voltage multiplier (assuming current requirements are low).

Depending on the PIC, you may even be able to use it's PWM module to generate a suitable voltage, check how the PICKit1 generates Vpp.

Thank you Nigel ... but my project is TO create a cheap intelligent controller to this kind of LCD. I have found a set of about 250 LCD at a very very low price (about 3 euro each) and they are 240 x 220 Pixels ... Actually I'm using an external negative power source, and my controller is almost working now. I just need to generate a negative power supply from 5 volt ...
Best regards

 

[Hero999]

It's called a buck-boost converter.
https://www.google.com/search?q=Buck-boost+converter&ie=UTF-8&oe=UTF-8

 

[justDIY]

if the -19v is just a micro-current bias voltage, a capacitor charge pump inverter might work too, eliminating the need to rely on magnetics