SMCJ33A - 1500W 33V Uni-Directional TVS Diode | Littelfuse
料号： SMCJ33A ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $0.62 | $0.62 |
| 10 | $0.54 | $5.40 |
| 100 | $0.41 | $41.00 |
| 500 | $0.33 | $165.00 |
| 1,000 | $0.27 | $270.00 |
| 3,000 | $0.22 | $660.00 |
SMCJ33A 概述
A TVS diode is a solid-state avalanche device engineered to remain non-conductive at normal circuit voltages and to conduct sharply above its breakdown threshold, shunting transient energy away from sensitive downstream components. The 1500W SMCJ family belongs to the broader class of voltage-clamp suppressors, which sit between linear regulators and Zener diodes in a power-tree-of-compromise breakdown hierarchy. SMCJ parts are the 1500W successors to the older 600W SMBJ and 400W SMAJ series, sharing identical DO-214 family footprints but offering 2.5x to 3.7x higher surge handling.
Key features include a glass-passivated die for stable leakage characteristics, low incremental surge resistance, fast response time of less than 1 ps from 0 V to Vbr minimum, and a low profile suitable for pick-and-place assembly. The DO-214AB package provides a flat heatslug and built-in strain relief that improves board-level reliability under thermal cycling. The Littelfuse variant is halogen-free and RoHS compliant, with a typical reverse leakage below 1 µA at the working voltage.
The SMCJ33A uses a uni-directional avalanche junction fabricated in a single-polarity die construction. Because the device is uni-directional it must be oriented correctly with the cathode connected to the protected node, otherwise forward conduction will occur on negative transients. The 33V standoff is the optimal match for 24V industrial buses (with ±20% tolerance) and 28V avionics rails, clamping before downstream components reach their 40-50V absolute-maximum ratings.
Typical applications include 24V industrial PLC input protection, telecom equipment -48V rectifier side protection (paired with a bidirectional part), automotive 24V truck body controller protection, RS-485/Profibus transceiver protection, and PoE port protection on the secondary side. The DO-214AB footprint allows reuse of existing land patterns designed for the SMCJ series. The wide operating temperature range of -55°C to +150°C supports both outdoor industrial and under-hood automotive deployments.
When designing with the SMCJ33A, observe maximum lead soldering temperature, and place the device as close as possible to the input terminal or connector to minimize parasitic inductance in the protected loop. For applications exposed to negative surges, select the SMCJ33CA bidirectional variant instead. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
直接替换替代料： SMCJ33A ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
本系列中的变体
可与以下型号直接替换的同系列型号： SMCJ33A （相同外形与封装尺寸） ——差异在于 Halogen-Free, Response Time, Polarity, Manufacturer, Operating Temperature.
快速对比工具——选择替代料号进行并排对比：
SMCJ33A
✅ 直接替换✓ 有现货
$0.22 / 个
查看数据手册 →SMCJ33A-Q
✅ 直接替换📋 参考替代料（不在目录中）
5.0SMDJ33A
✅ 直接替换📋 参考替代料（不在目录中）
SMCJ33A
✅ 直接替换✓ 有现货
$0.22 / 个
查看数据手册 →SMCJ33A
✅ 直接替换✓ 有现货
$0.22 / 个
查看数据手册 →SMCJ33CA
✅ 直接替换📋 参考替代料（不在目录中）
SMCJ33A-13-F
✅ 直接替换📋 参考替代料（不在目录中）
SMCJ33A 最大额定值与电气特性
| Peak Pulse Power (Ppp) | 1500 W (10/1000 µs waveform) |
| Working Standoff Voltage (Vrwm) | 33 V |
| Breakdown Voltage (Vbr) | 36.7 V to 44.0 V (test current It = 1 mA) |
| Maximum Clamping Voltage (Vc) | 53.3 V at Ipp = 28.2 A |
| Peak Pulse Current (Ipp) | 28.2 A (10/1000 µs) |
| Reverse Leakage (Ir) | 1.0 µA at Vrwm |
| Directionality | Uni-directional |
| 封装 | DO-214AB (SMC) |
| 安装类型 | Surface Mount |
| Response Time | < 1 ps (0 V to Vbr min) |
| 工作温度范围 | -55 °C to +150 °C |
| Repetition Rate (duty cycle) | 0.05% |
| Diode Construction | Glass-passivated junction |
| RoHS 状态 | Compliant |
| 无卤 | Yes (Littelfuse variant) |
| Lead-Free Finish | Yes |
SMCJ33A 引脚配置
| 引脚 1 | Cathode — Cathode terminal (marked with colored band) - connect to protected node / positive supply |
| 引脚 2 | Anode — Anode terminal - connect to ground / return path |
典型应用
SMCJ33A 适用于 6 应用s: 24V Industrial PLC Input Protection, Automotive 24V Truck Body Controller Protection, RS-485 / Profibus Fieldbus Protection, Telecom -48V Rectifier Side Protection, PoE Port Secondary-Side Protection, Building Automation / HVAC Control.
24V Industrial PLC Input Protection
The SMCJ33A protects 24V industrial PLC digital inputs from lightning-induced transients, inductive load switching, and ESD events on factory floor wiring. Its 33V working standoff is sized for a 24V nominal rail with +20% tolerance (28.8V max steady state), and the 53.3V clamping voltage remains below the 60V absolute-maximum of typical 24V opto-isolator and TVS-protected front-end ICs. The 1500W peak pulse rating comfortably exceeds IEC 61000-4-5 level 2 (1kV/2kA) surge requirements when the device is placed at the field-side connector. In a typical implementation, the SMCJ33A is mounted between the 24V field wire and chassis ground, with the cathode toward the protected node. The DO-214AB package allows direct replacement of older SMCJ5.0A parts and shares land patterns with the entire 5V-170V SMCJ family, simplifying multi-rail protection BOMs.
推荐
Automotive 24V Truck Body Controller Protection
The SMCJ33A provides secondary transient suppression on 24V commercial truck body controllers, agricultural machinery ECUs, and construction vehicle control units. Its 33V standoff covers the 28V nominal rail with peak load-dump-residual transients, and the 1500W rating handles the secondary pulse after a primary high-energy TVS or active clamp. For under-hood AEC-Q100/AEC-Q101 requirements, the Bourns SMCJ33A-Q automotive-qualified variant is a drop-in upgrade. In a typical truck body controller, the SMCJ33A is placed near the battery input connector in parallel with a higher-energy primary suppressor; this two-stage architecture provides both energy absorption and tight clamping. The -55°C to +150°C operating range supports cold-start cranking at -40°C and under-hood summer temperatures without derating. The DO-214AB package survives the thermal cycling of the automotive environment and is MSL-1 rated for unlimited floor life.
推荐
RS-485 / Profibus Fieldbus Protection
The SMCJ33A is widely deployed on RS-485 and Profibus transceiver protection circuits in industrial fieldbus nodes, where it shunts ESD and surge events from long cable runs to chassis ground before they reach the transceiver IC. Its 33V standoff exceeds the 12V common-mode voltage of RS-485 networks with adequate margin, and the sub-picosecond response time clamps fast ESD events (per IEC 61000-4-2 level 4) before transceiver damage occurs. The DO-214AB package is small enough to place directly at each connector pin pair without consuming valuable PCB area. A typical Profibus node uses three SMCJ33A devices: one on the +5V transceiver supply rail and two on each data line (A and B) to chassis ground. The 1500W rating exceeds the 1.5kV / 1kA surge levels typical of fieldbus installations in motor control cabinets. For intrinsically safe installations, the SMCJ33A's tight breakdown tolerance (±5%) ensures consistent protection coordination with safety barriers.
推荐
Telecom -48V Rectifier Side Protection
The SMCJ33A provides secondary transient protection on the -48V rectifier side of telecom equipment, where it clamps induced transients from lightning strikes on outdoor cabling before they propagate to the DC-DC converter and battery management circuits. Although the -48V rail is negative-referenced, the SMCJ33A is typically placed on the positive return (RTN) side and is paired with a higher-voltage bidirectional TVS (such as the SMCJ58CA) on the -48V feed for complete coverage. The 33V standoff is chosen to clamp below the 60V absolute-maximum of typical 48V hot-swap controllers. The 1500W rating handles the residual surge after the building entrance protector (BEP) and primary board-level TVS. The DO-214AB package allows automated pick-and-place with no special tooling, and its glass-passivated junction provides stable leakage over decades of continuous -48V operation. Operating temperature rating of -55°C to +150°C supports both outdoor cabinet and uncontrolled indoor deployments.
推荐
PoE Port Secondary-Side Protection
On the secondary (low-voltage) side of Power-over-Ethernet (PoE) PD interfaces, the SMCJ33A protects downstream DC-DC converters and PD controller ICs from line-cross events and ESD surges that couple through the PoE transformer. The 33V standoff is well-matched to PoE+ (25.5W) output rails of 12V, 24V, and 48V at the DC-DC input. The 1500W peak pulse handling exceeds the 1.5 kV / 8/20 µs surge levels specified in IEEE 802.3at for outdoor-rated PoE deployments. In a typical PoE PD design, the SMCJ33A is placed between the transformer's secondary winding return and chassis ground, in parallel with a smaller signal-line TVS for the data pairs. The DO-214AB package fits in the tight space available alongside the PD controller and the input bulk capacitor. The 0.05% maximum duty cycle rating supports the worst-case lightning-induced ringing seen in IEEE 802.3at outdoor installations without thermal runaway.
推荐
Building Automation / HVAC Control
The SMCJ33A protects 24V HVAC control boards, building automation gateways, and security panel inputs from inductive kickback of motors and solenoids, as well as from lightning-induced transients on long cable runs through the building. The 33V standoff matches 24V HVAC actuators with ±20% tolerance, and the 53.3V clamp protects downstream MCU I/O pins and relay drivers with 40V absolute-maximum ratings. A typical HVAC controller board uses SMCJ33A on the 24VAC rectified supply (after the bridge rectifier), the thermostat communication lines, and the relay coil flyback nodes. The DO-214AB package is small enough to place on the relay footprint already tab-stop-mount, simplifying BOM consolidation. The glass-passivated junction maintains stable leakage over the 10+ year lifetime of typical HVAC installations, and the -55°C to +150°C operating range covers outdoor rooftop unit and unconditioned mechanical room environments.
推荐
推荐产品汇总
工程参考数据： SMCJ33A ——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 | SMCJ33A (Taiwan Semi) | SMCJ33A-Q | 5.0SMDJ33A | SMCJ33A (Vishay) | SMCJ33A (Diodes Inc) |
|---|---|---|---|---|---|---|
| Brand | Littelfuse | Taiwan Semiconductor | Bourns | Littelfuse | Vishay | Diodes Incorporated |
| Package | DO-214AB (SMC) | DO-214AB (SMC) - same | DO-214AB (SMC) - same | DO-214AB (SMC) - same | DO-214AB (SMC) - same | DO-214AB (SMC) - same |
| Peak Pulse Power | 1500 W | 1500 W | 1500 W | 5000 W (+233%) | 1500 W | 1500 W |
| Working Standoff Voltage | 33 V | 33 V | 33 V | 33 V | 33 V | 33 V |
| Max Clamping Voltage | 53.3 V | 53.3 V | 53.3 V | 53.3 V | 53.3 V | 53.3 V |
| Peak Pulse Current | 28.2 A | 28.1 A | 28.2 A | 93.9 A (+233%) | 28.1 A | 28.2 A |
| Directionality | Uni-directional | Uni-directional | Uni-directional | Uni-directional | Uni-directional | Uni-directional |
| Automotive Qualified | No | No | Yes (AEC-Q101) | No | No | No |
关键差异点
- Industry-standard DO-214AB footprint with second-source availability from five major manufacturers （对比 P6SMB33A (DO-214AA, only 600W))
- Sub-picosecond avalanche response time preserves downstream semiconductor reliability （对比 Generic MOV (metal-oxide varistor))
- Glass-passivated junction with stable leakage over decades of continuous bias （对比 Unpassivated TVS (obsolete design))
- Drop-in upgradability to 5000W 5.0SMDJ series in same footprint （对比 P6KE33A (axial-leaded through-hole))
设计说明
Place the SMCJ33A as close as physically possible to the input connector or terminal block being protected. Lead and PCB-trace inductance of even 1 µH can develop 10-20 V of additional overshoot during an 8/20 µs surge, defeating the TVS clamping. Keep the trace from the connector to the TVS anode short and direct, and route the protected-side trace away from the connector trace to minimize coupling. For through-hole chassis-mounted connectors, place the TVS within 5 mm of the connector body.
Do NOT mount the SMCJ33A reversed. Because it is uni-directional, reverse mounting (cathode to ground) will forward-conduct any negative transient to the protected load through the low forward voltage drop (~1 V), defeating suppression and potentially destroying downstream components. Always verify the cathode band orientation against the schematic before powering the board. For applications with negative transients, choose the SMCJ33CA bidirectional variant instead.
Estimated: at maximum rated peak pulse power of 1500W for the 10/1000 µs waveform (1 ms pulse width), the SMCJ33A dissipates approximately 1.5 J per event. The thermal resistance junction-to-ambient is approximately 50 C/W on a standard JEDEC 1 sq inch copper pad. The repetitive rating (0.05% duty cycle) limits continuous surge events to one every 20 seconds to avoid thermal runaway. For high-repetition environments, derate or use the 5.0SMDJ33A.
Estimate the worst-case peak pulse current using Ipp = Ppp / Vc. For SMCJ33A: Ipp = 1500W / 53.3V = 28.1A, matching the datasheet. For a clamping voltage 20% below the maximum (Vc_min = 42.6V), the peak current could reach 35A if the source impedance is low. Select PCB trace widths of at least 0.5mm per ampere of surge current (12 mils per ampere) to prevent fusing during surge events.
The SMCJ33A's avalanche junction adds no significant EMI by itself. The most common EMI pitfall is using a TVS with too-high capacitance (such as the SMAJ family) on high-speed data lines - the SMCJ33A is designed for power-rail protection and may have higher capacitance than signal-line TVS parts. For RS-485/Profibus data lines, use a dedicated low-capacitance TVS (such as the PESD series) in parallel with the SMCJ33A on the supply rail.
合规信息
RoHS and halogen-free compliant per Littelfuse product page. The standard SMCJ33A is NOT AEC-Q100/AEC-Q101 qualified - choose the Bourns SMCJ33A-Q or Diodes Incorporated automotive-compliant variant for automotive applications. Lead-free reflow profile per JEDEC J-STD-020.