Hi, i use opt101 to measure blood flow.
I make circuit bipolar supply +-5V with 0.1uF bypass cap, common pin to GND.
Light source is 250Hz PWM.
when I use 1M ohm internal resister, 60Hz noise is not occur.
But, when I use series resistor (datasheet 4.(a)) 5M ohm with 10pF 60Hz noise is occur.
How can i reduce this 60Hz noise? (use not notch filter, only OPT101)