The PS9122 is an optical coupled high-speed, active low type isolator containing a GaAlAs LED on the input side and a photodiode and a signal processing circuit on the output side on one chip. The PS9122 is a high-speed digital output type photocoupler designed specifically for low circuit current. The PS9122 is in 5-pin plastic SOP (Small Outline Package) and is suitable for high density application.