The MOC3021SR2M and CT3021S are random-phase optoisolators with a triac driver output, manufactured by Fairchild Semiconductor (now ON Semiconductor). These devices are designed to isolate low-voltage control circuitry from high-voltage AC loads. They are commonly used to control AC power devices such as TRIACs in solid-state relays and other applications.

Applications

• Solid-state relays (SSRs)
• AC motor control
• Lighting control
• Solenoid and valve control
• Temperature control

Features

• Peak Blocking Voltage: 400V
• Isolation Voltage: 7500 Vpk
• On-State Current: 1 Amp
• Trigger Current: 5 mA (typical)
• Package: SMD (Surface Mount Device) - SOIC-6
• Random Phase Operation: No zero-crossing detection
• Compliance: RoHS Compliant

Benefits

• Electrical Isolation: Provides high voltage isolation between the control circuit and the AC load.
• Direct AC Load Control: Enables direct control of AC loads with a low-current DC signal.
• Solid-State Reliability: Offers long-term reliability compared to mechanical relays.
• Compact Size: Small surface mount package saves board space.
• Simplified Circuit Design: Reduces the complexity of AC load control circuits.
• High Isolation Voltage: Ensures a high degree of safety and protection.

Additional Details

The MOC3021SR2M and CT3021S optoisolators consist of an infrared emitting diode (IRED) optically coupled to a TRIAC driver. When current is applied to the IRED, it emits light, which activates the TRIAC driver, allowing current to flow through the TRIAC connected to the AC load. The random-phase operation means that the TRIAC can be triggered at any point in the AC cycle, making it suitable for a variety of applications where precise timing is not critical. The high isolation voltage (7500 Vpk) provides a significant safety margin. Always refer to the manufacturer's datasheet for complete specifications and application guidelines.