VOM452T & VOM453T High Speed Optocouplers Vishay Semiconductors VOM452T and VOM453T High Speed Optocouplers each consist of a GaAlAs infrared emitting diode, optically coupled with an integrated photo detector and a high speed transistor. The photo detector is junction isolated from the transistor to reduce miller capacitance effects. Vishay Semiconductors VOM452T and VOM453T High Speed Optocouplers have open collector output and very high common mode transient immunity. The open collector output function allows circuit designers to adjust the load conditions when interfacing with different logic systems such as TTL, CMOS, etc.