MOC3021 Triac Driver: Pinout, Datasheet, Equivalent [Video]

The MOC3021 is a Zero-Crossing TRIAC driven Optocoupler or Optoisolator. As we know, the term Optocoupler/Optoisolator means the same thing that we use light to indirectly couple circuit sets. The speciality of MOC3021 is that it has a Zero-Crossing ability and is driven by a Triac.

This video tells how to make an Arduino based 110/220vac Bulb dimming Control system using MOC3021

Catalog

MOC3021 Pinout

MOC3021	MOC3021 Pinout

MOC3021 Features

• Opto-isolator with Zero-Crossing Triac Driver

• Input LED Diode Forward Voltage: 1.15V

• LED Forward Latch Current: 15mA

• TRIAC output terminal voltage: 400V (max)

• TRIAC peak output current: 1A

• Available as 6-pin PDIP with and without M-suffix

MOC3021 Equivalent

MOC3043

Alternatives Opto-couplers: MCT2E (non-Zero transistor), MOC3041 (Non-Zero Cross TRIAC), FOD3180 (High-Speed MOSFET),

Where to use MOC3021 Phototransistor Optocoupler

Since the output is driven by the TRIAC, we can drive loads up to 400V and the triac can operate in both directions, so controlling the AC loads will not be a problem. Also, since it has a zero-crossing capability, when the AC load is switched on for the first time, the TRIAC will start conduction only after the AC wave reaches 0V, so we can avoid direct peak voltages to the Load and thus prevent it from being damaged. It also has a decent rise and fall time and can therefore be used to control the output voltage.

This feature of the MOC3021 makes it the ideal choice for controlling high voltage AC loads through digital controllers such as MPU/MCU. Since the output is controlled, the intensity of the light or the speed of the AC motor can be controlled. So if you're looking for an opto-isolator to control an AC application through DC, this IC might be the right choice for you.

How to Use MOC3021 Phototransistor Optocoupler

The MOC3021 is normally used to control the AC appliance, such as the brightness of the bulb, the speed of the motor, etc. Either way, due to its limited current rating, an opto-coupler will not be allowed to drive loads directly. In our case, they are normally connected to another power switch like the Triac, this TRIAC will be able to provide enough current to drive the loads and will be controlled using an opto-coupler. A simple circuit diagram in which the AC bulb is controlled by a microcontroller is shown below.

MOC3021 Microcontroller Interfacing Diagram

The MOC3021 can be used to switch loads by simply switching the LED on or off, or we can also use PWM signals to switch the LED and thus the TRIAC. When the TRIAC is switched by using PWM signals, the output voltage across the load can be controlled by controlling the speed/brightness of the load.

It is important to understand the switching speed of the opto-coupler when trying to switch AC loads. This switching speed depends on the voltage amplitude controlled by the TRIAC and the operating ambient temperature. The graph below will give you a good understanding of how long it takes.

MOC3021 Switching Speed Graphic

For example, at 30 degrees Celsius of ambient temperature, the rate of voltage change with respect to time will be 9V per unit time, where the unit time is uS. So we can change 9V in one micro second.

MOC3021 Applications

• AC Light dimmers

• Strode lights

• AC motor speed control

• Noise coupling circuits

• Controlling AC loads using MCU/MPU

• Ac/DC Power control

MOC3021 Package

Component Datasheet

MOC3021 Datasheet

Ordering & Quality

Photo	Mfr. Part #	Company	Description	Package	PDF	Qty	Pricing (USD)
	MOC3021M	Company:ON Semiconductor	Remark:OPTOISOLATOR 4.17KV TRIAC 6DIP	Package:6-DIP (0.300", 7.62mm)	DataSheet	In Stock:2217 Inquiry	Price: 1+: $0.62000 10+: $0.48400 100+: $0.31030 500+: $0.26682 1000+: $0.20601 2500+: $0.18615 5000+: $0.17374 10000+: $0.16754	Inquiry
	MOC3021SR2M	Company:ON Semiconductor	Remark:OPTOISOLATOR 4.17KV TRIAC 6SMD	Package:6-SMD, Gull Wing	DataSheet	In Stock:3000 Inquiry	Price: 1000+: $0.22695 2000+: $0.21182 5000+: $0.20426	Inquiry