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    SubjectRe: [PATCH] leds: driver for ab5500 high voltage leds
    On 12/07/2011 04:07 PM, Linus Walleij wrote:
    > On Sat, Dec 3, 2011 at 11:49 PM, Denis Kuzmenko <> wrote:
    >> (snip)
    >>> diff --git a/drivers/leds/leds-ab5500.c b/drivers/leds/leds-ab5500.c
    >> (snip)
    >>> +/*
    >>> + * Driver for HVLED in ST-Ericsson AB5500 analog baseband controller
    >>> + *
    >>> + * This chip can drive upto 3 leds, of upto 40mA of led sink current.
    >> Can't get these are High Voltage or High Current LEDs?
    >> If Voltage why haven't you wrote about supplied voltage but wrote about
    >> max. current?
    > The three channels are indeed high-voltage LEDs, they supply
    > up to 20V from a supply voltage of some standard mobile handset
    > battery at say 3.8 V or so. But there is no register to control the
    > voltage or anything like that.
    > My naive understanding is that you set the current limit and then
    > the HV transformer (I guess this is a buck converter of some kind)
    > will raise the voltage level until it either (A) cannot raise it any more
    > at c:a 20V or (b) the current limit is reached.
    > I suspect this is because for LEDs of this type you get a
    > specified current but the voltage just has to be "high enough"
    > to break through some diode barrier threshold or so. After
    > that intensity is controlled by limiting the current.
    > Does this suffice as explanation...?
    > Yours,
    > Linus Walleij

    Yeah, It does, thank you.
    Does it worth to make additional comment in code to avoid further questions?

    Best regards, Denis Kuzmenko.

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