BUY QCK3 https://www.utsource.net/itm/p/5030998.html
SLOTTED OPTICAL SWITCH
Description: Quad Comparator Features: Low Supply Current: 0.6mA High Speed: 0.8μs Low Input Offset Voltage: 0.5mV Low Input Bias Current: 0.1nA Low Input Offset Current: 0.1nA Low Input Voltage Noise: 0.1μV/√Hz Low Input Offset Voltage Drift: 0.1μV/°C Low Output Saturation Voltage: 0.2V Application: Battery-Powered Equipment Portable Instruments High-Speed Data Acquisition Systems Automotive Applications Industrial Control Systems (For reference only)