The ILQ74 is an optically coupled pair with a GaAIAs infrared LED and a silicon NPN phototransistor. Signal information, including a DC level, can be transmitted by the device while maintaining a high degree of electrical isolation between input and output. The ILQ74 is especially for driving medium-speed logic, where it may be used to eliminate troublesome ground loop and noise problems. Also, it can be used to replace relays and transformers in many digital interface applications, as well as analog applications such as CTR modulation. the ILQ74 has four isolated channels per package.