Backlight Power Measurement

Paul Fertser fercerpav at
Sat Oct 10 08:56:56 CEST 2009

Paul Fertser <fercerpav at> writes:
> Aaron Carroll <xaaronc at> writes:
>> To determine backlight power, I've got a DAQ sampling the
>> voltage drop across R1763 (Rsense for the PCF50663 LED
>> supply) which gives me the current, and I'm sampling LED+
>> at C1764 for the input voltage.  I was hoping the product
>> of these two would yield the power consumed by the
>> backlight and Rsense.
> ...
> You've got quite puzzling and unexpected results indeed. Could you
> please provide us with the actual measurements data?

OTOH 66.6% efficiency for a boost converter doesn't sound like
something really exceptionally low. And moreover we lack the datasheet
for L1704 to be able to give proper estimates.

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