usually a boost regulator, depending on the stack of LEDs
may go up to 12 to 18 volts

freq keep moving up, was around 1MHz now they're going
around 8 to 10MHz, but very localized near the IC

see Micrel's app notes 

      - Robert -


On Mon, 18 Dec 2006 09:36:56 -0600
 Ken Javor <ken.ja...@emccompliance.com> wrote:
> Forum Members,
> 
> I am evaluating a PDA-like device for EMI/explosive
> atmosphere usage. The
> device has what appears to be an LCD type display, which
> means it has
> back-lighting. While the device runs off 4.2 Vdc
> batteries, which are deemed
> a safe potential, I expect that the back-light potential
> is at a much higher
> level, and that getting from 4.2 Vdc to that higher
> potential can be
> potentially noisy from an EMI point-of-view.
> 
> Any commentary/experience to share?
> 
> Thank you,
> 
> Ken Javor

-

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