[Arm-netbook] LCD LED driver IC recommendation

[jm]

On Wed, 2013-01-09 at 09:37 +0000, luke.leighton wrote:
> On Wed, Jan 9, 2013 at 8:23 AM, jm <joem at martindale-electric.co.uk> wrote:
> > On Tue, 2013-01-08 at 20:46 +0000, luke.leighton wrote:
> >> hi folks,
> >>
> >> can anyone recommend an LCD backlight driver IC to drive an
> >> HV070WS1-100?  also the datasheet's a bugger: one part of it says it
> >> needs 40V 30mA, and another says it needs 3.7V @ 420mA - anyone know
> >> which is correct?
> >
> > 40V is absolute max rating.
> >
> > Typical is 15.5V / 80mA for decent lit screen.
> 
>  oh, ok.  that should be easier to find.
> 
> > But obviously a switch mode power supply LED driver chip that has dimmer
> > controls is needed to control brightness and that must be able to take
> > the battery voltage and convert it to supply 15.5V (17V max) @ 80mA to
> > light the display properly.
> 
>  yeah, that's why i picked the LM1755, but it turns out it's micro-bga
> grid, and i don't want micro-bga grid parts.
> 
>  i was kinda planning to use the STM32F to do PWM.
> 
>  i think i know of a chip that will do - it's cheap and cheerful but
> it's DIL (which will do fine).
> 
>  any recommendations however would be great.

This link shows a couple of chips that have various input and output
voltages and currents: http://tinyurl.com/bgbdsaq 

>From that list, a device like LM3432 might be what you are looking for.
But I'm no expert on LCD back light.
The LCD supplier should be able to recommend a good back light chip +
circuit, or get support from the factory that made it.
Avoid charge pumps - they are cheap because they don't used inductors,
however, I believe they are not that efficient.
High frequency inductor based switch mode supplies have >80% efficiency
is probably what you need for battery based operation.