MOC3021

Triac, SCR Output Optoisolators Overview

The MOC3021 is a Triac and SCR output optoisolator manufactured by Lite-On Inc. It features a single channel with a phototriac output and lacks a zero-crossing circuit. The device provides 5000 Vrms isolation voltage and operates within a temperature range of -40°C to 100°C. Key electrical parameters include a maximum continuous output current of 100 mA, an off-state output voltage (VDRM) of 400 V, and a power dissipation of 330 mW. The input side supports a maximum forward current of 50 mA with a typical forward voltage of 1.15 V to 1.2 V.

Triac, SCR Output Optoisolators Feature Summary

• Non-zero-crossing Triac output for random phase control applications
• High isolation voltage capability of 5000 Vrms
• AlGaAs infrared LED coupled with photosensitive Triac

Triac, SCR Output Optoisolators Applications

• Control of resistive, inductive, or capacitive loads
• Motor and solenoid drive circuits
• Isolation for AC line voltage switching

Triac, SCR Output Optoisolators Procurement Notes

Verify the specific package variant required, as the MOC3021 series includes through-hole PDIP-6 and surface-mount SMD options such as the MOC3021S-TA1. Confirm that the non-zero-crossing characteristic aligns with the application requirements, as this distinguishes it from zero-crossing variants like the MOC302x series. Ensure the supplier provides official datasheets confirming the 5000 Vrms isolation rating and operating temperature range.

Triac, SCR Output Optoisolators Selection Notes

Select the MOC3021 when random phase firing is necessary, such as in dimmer controls or speed regulators, rather than for noise-sensitive switching where zero-crossing is preferred. The 400 V off-state voltage limits suitability for higher voltage AC lines without external protection. Consider the 100 mA RMS output current limit when driving larger loads, potentially requiring an external Triac or SCR stage.

Triac, SCR Output Optoisolators Part Context

The MOC3021 belongs to the MOC302x family of Triac and SCR output optoisolators from Lite-On Inc. This family is designed for general-purpose AC load control. Unlike the MOC3021, other members like the MOC3022 feature zero-crossing detection. The component is widely used in industrial and consumer electronics for galvanic isolation between low-voltage control logic and high-voltage AC power stages.

Triac, SCR Output Optoisolators Replacement Considerations

Direct substitutes within the same family include the MOC3022, though it features zero-crossing detection which alters switching behavior. For identical non-zero-crossing functionality, verify equivalent parts from other manufacturers offering 400 V Triac outputs with similar isolation ratings.