MOC3021S-TA1-A - 400V Random-Phase TRIAC Optocoupler SMD-6
料号： MOC3021S-TA1-A ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $0.5 | $0.50 |
| 10 | $0.39 | $3.90 |
| 100 | $0.27 | $27.00 |
| 500 | $0.2 | $100.00 |
| 1,000 | $0.15 | $150.00 |
| 5,000 | $0.11 | $550.00 |
MOC3021S-TA1-A 概述
A TRIAC-driver optoisolator is an optocoupler whose output stage is a photo-triggered bilateral thyristor (TRIAC), used to bridge low-voltage logic and a mains- or AC-line-driven TRIAC while providing galvanic isolation. In the component taxonomy, MOC3021S-TA1-A belongs to the optocoupler family, then to TRIAC/SCR-output optoisolators, then to signal/power isolation devices, and finally to discrete semiconductors / isolation components.
Key features include random-phase triggering (no zero-crossing detection), an input forward current (IF) of typically 10-15 mA for guaranteed trigger, a peak off-state voltage of 400 V minimum, a holding current (IH) of about 100 uA, and a 6-pin SMD footprint that supports automated assembly. The non-zero-crossing behavior means it can trigger at any point on the AC sinusoid, making it well suited to phase-angle control circuits such as lamp dimmers and motor-speed controllers.
Optically, the device pairs a high-efficiency GaAs IR LED with a photosensitive TRIAC chip mounted on a ceramic isolation substrate inside a clear epoxy body. The 5000 Vrms isolation barrier (Viso function) exceeds IEC 60747-5-2-style reinforced isolation requirements for line-voltage interface circuits, and the minimum 100 V/us dV/dt ensures the output TRIAC will not latch on falsely due to fast AC-line transients.
Typical applications include solid-state relay (SSR) front-ends, AC lamp dimmers, small AC motor drivers, solenoid drivers, and interface circuits for microcontrollers driving line-voltage TRIACs. Designers choose this part when they need a non-zero-crossing (random-phase) trigger so phase-angle modulation becomes possible.
When designing with this part, place a buffer resistor and snubber network across the output TRIAC, and remember that this part triggers at any phase angle - it does not wait for the next zero-cross. For zero-crossing loads, choose a MOC3041/MOC3043 instead. The SMD gull-wing package requires careful solder-pad design for clean reflow.
This synthesis integrates distributor pricing, drop-in alternatives, and practical design notes - information not found directly in the manufacturer datasheet.
直接替换替代料： MOC3021S-TA1-A ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
快速对比工具——选择替代料号进行并排对比：
MOC3020S-TA1
✅ 直接替换📋 参考替代料（不在目录中）
MOC3022S-TA1
✅ 直接替换📋 参考替代料（不在目录中）
MOC3023S-TA1
✅ 直接替换📋 参考替代料（不在目录中）
MOC3021SM
✅ 直接替换📋 参考替代料（不在目录中）
VO3021
✅ 直接替换📋 参考替代料（不在目录中）
MOC3021S-TA1-A 规格参数
| Manufacturer | Lite-On Technology |
| Part Number | MOC3021S-TA1-A |
| 输出类型 | Triac (non-zero-cross / random phase) |
| Number of Channels | 1 |
| Input-to-Output Isolation Voltage (Viso) | 5000 Vrms (min) |
| Repetitive Peak Off-State Voltage (VDRM) | 400 V (min) |
| Critical Rate of Rise of Off-State Voltage (dV/dt) | 100 V/us (min) |
| Input Forward Current (IF, trigger) | 10 mA (typ), 15 mA (max rated) |
| Holding Current (IH) | 100 uA (typ) |
| 封装 | 6-SMD, Gull-Wing (DIP-6 SMD) |
| 安装类型 | Surface Mount |
| 工作温度 | -40C to +100C |
| MSL 等级 | 1 |
| RoHS 状态 | Compliant |
| Tape & Reel Orientation | TA-1 (AEC-Q-style tape orientation) |
MOC3021S-TA1-A 引脚配置
| 引脚 1 | LED Anode (+) — Anode of the input infrared-emitting diode |
| 引脚 2 | LED Cathode (-) — Cathode of the input infrared-emitting diode |
| 引脚 3 | NC — Not connected (per datasheet) |
| 引脚 4 | MT1 — Output photo-TRIAC main terminal 1 |
| 引脚 5 | NC — Not connected (per datasheet, substrate tied to MT1 internally) |
| 引脚 6 | MT2 — Output photo-TRIAC main terminal 2 |
典型应用
MOC3021S-TA1-A 适用于 6 应用s: Solid-State Relay (SSR) Front-End, AC Lamp Dimmer (Phase-Angle Control), Small AC Motor Speed Controller, Solenoid and Valve Driver, Microcontroller AC Line Interface, Temperature / Heater Power Regulator.
Solid-State Relay (SSR) Front-End
The MOC3021S-TA1-A's 5000 Vrms isolation barrier and 400 V VDRM photo-TRIAC output make it the canonical front-end for solid-state relays switching 120-240 VAC loads. The LED input (IF ~10-15 mA) is driven directly from microcontroller GPIO through a current-limit resistor, while the output photo-TRIAC gates an external power TRIAC (e.g., BTA16) for the actual load switching. The random-phase trigger permits zero-cross or phase-angle SSR topologies, with dV/dt >=100 V/us suppressing false triggering on noisy mains.
推荐
AC Lamp Dimmer (Phase-Angle Control)
For incandescent or resistive AC lamp dimmers, the MOC3021S-TA1-A is fired by a microcontroller timed to a zero-cross detector; because it is random-phase (non-zero-cross), it can trigger the external TRIAC at any phase angle on the AC sinusoid, enabling phase-angle modulation of lamp brightness. The 400 V VDRM comfortably covers 230 VAC peak plus margin, and 5000 Vrms isolation lets the low-voltage logic side touch mains safely. The holding current (~100 uA typ) means incandescent lamps stay latched; small LED loads may need a bleed resistor.
推荐
Small AC Motor Speed Controller
The MOC3021S-TA1-A is used to gate an external power TRIAC driving small universal or shaded-pole AC motors (fans, pumps, small tools). Phase-angle control through this optocoupler varies RMS voltage across the motor, giving variable speed. The 5000 Vrms isolation protects low-voltage control electronics from inductive kickback, and the 100 V/us dV/dt minimum plus an external snubber (R-C across MT1-MT2) handles inductive load transients reliably.
推荐
Solenoid and Valve Driver
Industrial solenoid and AC-line valve drivers use the MOC3021S-TA1-A as the isolating gate driver between a 24 V logic controller and the 120-230 VAC solenoid coil. The 5000 Vrms isolation meets reinforced isolation requirements for industrial environments, and the random-phase trigger permits either on/off switching or pulsed-PWM-like phase-angle control for proportional solenoid valves. The MSL-1 rating simplifies high-volume reflow assembly.
推荐
Microcontroller AC Line Interface
Any 5 V or 3.3 V microcontroller driving an AC line load benefits from the MOC3021S-TA1-A's galvanic isolation. The IR LED input (pin 1-2) draws ~10 mA through a current-limit resistor from GPIO; the output photo-TRIAC (pins 4-6) drives the gate of an external power TRIAC through a gate resistor. This isolation topology is industry-standard for safe line-voltage interfaces in IoT, smart-home, and appliance control boards.
推荐
Temperature / Heater Power Regulator
Closed-loop AC heater power regulators use the MOC3021S-TA1-A to phase-angle-modulate the AC mains feeding a resistive heating element, proportional to a temperature sensor's PID output. The 400 V VDRM covers 230 VAC peak, and 5000 Vrms isolation separates the safety-critical mains wiring from the low-voltage sensor and microcontroller. The random-phase behavior is essential here - a zero-cross optocoupler could not deliver proportional heating.
推荐
推荐产品汇总
工程参考数据： MOC3021S-TA1-A ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | MOC3020S-TA1 | MOC3022S-TA1 | MOC3023S-TA1 | MOC3021SM | VO3021 |
|---|---|---|---|---|---|---|
| Brand | Lite-On | Lite-On | Lite-On | Lite-On | onsemi | Vishay Intertechnology |
| Package | 6-SMD, Gull-Wing | 6-SMD, Gull-Wing | 6-SMD, Gull-Wing | 6-SMD, Gull-Wing | 6-SMD, Gull-Wing | 6-SMD, Gull-Wing |
| VDRM (Peak Off-State Voltage) | 400 V (min) | 400 V (min) | 400 V (min) | 400 V (min) | 400 V (min) | 400 V (min) |
| Viso (Isolation Voltage) | 5000 Vrms | 5000 Vrms | 5000 Vrms | 5000 Vrms | 5300 Vrms (typ) | 5300 Vrms (typ) |
| Trigger Type | Random Phase (Non-Zero-Cross) | Random Phase | Random Phase | Random Phase | Random Phase | Random Phase |
| Trigger IF (typ) | 10 mA | 30 mA (max) | 10 mA (max) | 5 mA (max) | 15 mA (max) | 10 mA (typ) |
| dV/dt (min) | 100 V/us | 100 V/us | 100 V/us | 100 V/us | 100 V/us | 100 V/us |
| RoHS / Lead-Free | Yes | Yes | Yes | Yes | Yes | Yes |
关键差异点
- Random-phase trigger supports phase-angle control circuits (lamp dimmers, motor speed, proportional solenoids) （对比 MOC3041 (zero-cross optocoupler))
- Single Lite-On part family covering four IF trigger-current grades (MOC3020/3021/3022/3023) for design flexibility （对比 onsemi MOC3021SM)
- MSL 1 rating simplifies reflow production (no dry-pack bag required) （对比 Vishay VO3021)
设计说明
Always size the input LED current-limit resistor so that IF stays between the trigger-maximum (typically 15 mA) and the trigger-minimum (typically 5-10 mA) for the specific family member. For MOC3021S-TA1-A at 5 V GPIO, a 330 ohm resistor gives ~11 mA IF (5 V - 1.2 V forward drop) / 330 = 11.5 mA. Too low an IF will fail to trigger the photo-TRIAC; too high an IF will accelerate LED aging and may exceed absolute maximum.
Maintain at least the datasheet-recommended creepage and clearance between the input-side traces (pins 1-2) and the output-side traces (pins 4-6) on the PCB. Even with 5000 Vrms internal isolation, a PCB surface arc would defeat the isolation. Keep any external snubber network compact and located within 5 mm of MT1-MT2 pins. Add a TVS or MOV across the mains side for transient protection beyond the 100 V/us dV/dt rating.
The MOC3021S-TA1-A output photo-TRIAC only handles a few hundred mA peak surge - it is intended to GATE an external power TRIAC (e.g., BTA08, BTA16, BTA25), NOT to switch the AC load directly. Driving the load through the MOC's internal TRIAC will exceed IT(RMS) ratings and destroy the part. Always use the MOC3021 as a gate-coupler, with the power TRIAC doing the actual load switching.
Estimated: at 10 mA continuous IF and 1.2 V Vf across the input LED, the input dissipates ~12 mW; output thermal is dominated by the external power TRIAC. The MOC3021S-TA1-A itself does not require a heatsink in normal gate-driver service. If used outside the datasheet's recommended operating area (e.g., driving inductive loads without a snubber), allow at least 200 mil of continuous ground copper under the package for thermal relief.
合规信息
RoHS compliant per Lite-On product page and distributor listings (DigiKey, Mouser, LCSC). MSL 1 per Lite-On datasheet. Halogen-free and conflict-minerals status not explicitly stated in verified web data - marked unknown.
