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In addition to this, the LED is being driven by AD8618 for CN0312 which forms a simple constant current source. the current source is being defined by the resistor divider that generates certain bias voltage derived from Vref.
The schematics as published in the article on EDN shows the power connection of the AD8618 at the source of the MOSFETs (output ORed node). The AD8619 is a quad op-amp, so only 1 power connection is shown.