MOC3021 Reference Tables, Pins & Specifications

Pin reference

Signal names, electrical functions and connection guidance

DIP-6

Physical pin numbers6 pins

Scroll within the table to see all columns and rows.

MOC3021 pin functions and connections
Signal	Type	Function & connection
A	Infrared LED anode	Positive terminal of the optical input emitter. Connection guidance Use a buffered 5 V source through 220 Ω. Drive above the required trigger current with temperature and tolerance margin.
K	Infrared LED cathode	Input-side return for the emitter current. Connection guidance Return to GND_A. Do not join the input return to the isolated output domain.
NC	Not connected	No intended internal connection. Connection guidance Leave unconnected.
MT	Main output terminal	One terminal of the light-triggered bilateral switch. Connection guidance Connect to the isolated AC source return in the example. This is a triac driver, not a high-power load switch.
DNC	Do not connect	Internal triac substrate lead. Connection guidance Leave open; do not route a signal through this pin. NC in the manufacturer symbol does not authorize connecting this substrate lead.
MT	Main output terminal	Other terminal of the light-triggered bilateral switch. Connection guidance Connect through the pulse/load resistor to the isolated AC source. No zero-cross detector: trigger timing follows the optical input and available output voltage.

Selected onsemi family

Manufacturer-referenced values5 parameters

Scroll within the table to see all columns and rows.

Parameter	Value	Conditions / notes
Through-hole / surface-mount	MOC3021M / MOC3021SR2M	646BX / formed 646BY
Input	1 anode · 2 cathode	Current limiting required
Output	Main terminals 4 and 6	Bilateral triac-driver output
Leave open	Pin 3 NC · pin 5 substrate	Never use pin 5 as a wiring junction
Trigger type	Random-phase	No built-in zero-cross detector

Read the selected manufacturer’s variant rather than assuming all similar part names match.

Ambient 25°C unless noted

Manufacturer-referenced values6 parameters

Scroll within the table to see all columns and rows.

Parameter	Value	Conditions / notes
Emitter continuous / reverse	60 mA / 3 V	Separate stress limits
Output blocking	400 V peak	Either direction
Output surge	1 A, 100 µs at 120 pulses/s	Not continuous load current
Input / detector dissipation	100 / 300 mW	Derate above 25°C
Total dissipation	330 mW	Combined input and detector limit
Ambient / junction max.	−40 to +85°C / +100°C	Storage −40 to +125°C

A driver output must not be used as a mains power switch.

TA 25°C; selected device

Manufacturer-referenced values6 parameters

Scroll within the table to see all columns and rows.

Parameter	Value	Conditions / notes
LED forward voltage	1.15 V typical; 1.5 V maximum	IF 10 mA
LED trigger current	15 mA maximum	Main-terminal voltage 3 V
Peak on-state voltage	1.8 V typical; 3 V maximum	ITM 100 mA; IF at rated trigger
Holding current	100 µA typical	Either direction
Off-state leakage	10 nA typical; 100 nA maximum	Rated blocking voltage; input off
Static dV/dt	1000 V/µs minimum	Input off; specified rated-voltage test

The low-current demonstration uses an explicit drop assumption.

Device certification does not certify the assembled board

Manufacturer-referenced values6 parameters

Scroll within the table to see all columns and rows.

Parameter	Value	Conditions / notes
Input-output dielectric test	4170 Vrms · 1 minute	Test condition, not continuous working voltage
External creepage / clearance	≥7 mm / ≥7 mm	Selected standard package; check installed board
Body	8.51 × 6.35 mm nominal	2.54 mm pitch; 3.40 mm nominal mould height
DIP footprint	7.62 mm rows	Original 1 mm holes, 1.8 mm pads
SMD recommended lands	1.525 × 1.78 mm	9.015 mm rows; 10.54 mm outer span
Isolation layout	Keep both domains separate	Slots, copper, contamination and enclosure affect the system

Use the relevant safety approval option and complete system insulation design.

Buffered input and separate isolated output source

Manufacturer-referenced values7 parameters

Scroll within the table to see all columns and rows.

Parameter	Value	Conditions / notes
Input source / resistor	5 V_A / 220 Ω	Input switch or buffer must source the LED current
Nominal LED current	17.50 mA	Assumed VF 1.15 V
At 1.5 V LED drop	15.91 mA	Nominal supply/resistor only; temperature and tolerance remain
Output source / load	12 V RMS isolated / 2.2 kΩ	Resistor ≥0.25 W
Approximate peak load	6.90 mA	(12√2−1.8)/2200; assumed output drop
Resistor power upper bound	65.5 mW	12²/2200; neglects device drop
Returns	GND_A isolated from AC_B	No wire crosses the barrier

Calculated teaching values, not a measured switching waveform.