Pins 5 and 6 should not be used electrically. Leave each on an isolated PCB pad solely for soldering/mechanical stability, as the datasheet specifies.
The diagram shows that these package leads are physically connected to the internal LED cathode/driver nodes, but Maxim does not expose them as supported signals. They may exist for internal manufacturing, wafer/package testing, or package construction, but no user test or application function is specified.
Therefore:
Do not connect them to GND, PGND, a test point, or another net.
Give each pin its own footprint pad.
Do not join pins 5 and 6 together.
Avoid copper pours accidentally connecting to these pads.
The internal LED current path is already controlled by the MAX30102’s LED drivers; external access to the cathodes is neither required nor supported.
There is no supported user scenario for pins 5 and 6—not even calibration. The datasheet explicitly defines them as no-connect pins whose pads exist only for mechanical stability.
They are likely bonded to the LED cathode nodes for factory-only purposes, potentially including:
Production probing or characterization
LED/driver screening before final test
Failure analysis
Package or die-test accessibility
Those possibilities are not documented user functions, so they should not be relied upon. Calibration of the MAX30102 is performed through its I²C registers and software processing—LED current, pulse width, sample rate, ADC range, and signal correction—not through pins 5 or 6.
Connecting external circuitry could disturb the regulated LED-current pulses, corrupt measurements, exceed driver ratings, or cause unpredictable behavior across device revisions. In the footprint, retain separate solder pads but leave both pads electrically isolated.