Lpc2000

I had the same problem with a seiko lcd screen.
The simplest solution, is to use one of the most common chips on the
market. MAX232 or MAX3232 for 3.3V. It generates -12V.

If you take a look in the datasheet, you will find all the info there.


--- In lpc2000@yahoogroups.com, Onestone <onestone@b...> wrote:
>
> After messing with this one for years I finally went to Winstar and get 
> mine on baord for free, however prior to that for digital control I
used 
> the MAX686, not a cheapest solution but solid, and not too expensive. 
> The other cheap way might be to use an MC34063, they are only $1,
but no 
> digital control, or ON/OFF control without a bit of messing. I used an 
> MC14051 ($0.38) and a variety of resistors to get numerous voltage
steps.
> 
> Cheers
> 
> Al
> 
> Sean wrote:
> 
> >Sorry for the OT post, but I figure that since this is something
common to 
> >embedded projects you guys might have an elegant solution.
> >
> >I'm looking to create a contrast voltage (typ -13V 10mA) and a LCD
Drive 
> >voltage (min -23V 10mA), onboard I have +5V, +3.3V and Vin which is 
> >typically +12V.  Ideally the contrast should be digitally controllable.
> >
> >The big part of the problem: it needs to be relatively cheap.
> >
> >I've been having a hard time trying to figure out the best way to do 
> >this.  The best way that I can think of so far is going to be via
voltage 
> >multipliers.  I.e. take 3.3, invert and quadruple to get -13.2V for
the 
> >contrast, and then double again to get -26.4V for the LCD Drive.  I
don't 
> >know however if I can handle 10mA this way after octupling the voltage.
> >
> >I'm trying to stay away from switched regulators, as they can get
expensive.
> >
> >Thanks for any suggestions that you may have.
> >
> >-- Sean
> >
> >
> >
> > 
> >Yahoo! Groups Links
> >
> >
> >
> > 
> >
> >
> >
> >
> >  
> >
>