STMicroelectronics SMC30J188A

Overview

SMC30J188A from STMicroelectronics is a unidirectional transient voltage suppression (TVS) diode designed for high-energy surge protection in DC power lines and signal interfaces. It delivers 3000 W peak pulse power (10/1000 µs), clamps at 328 V (max) under 9 A surge current, and operates up to 175 °C junction temperature - enabling robust protection in industrial motor drives, telecom power supplies, and solar inverters.

For engineers reviewing the SMC30J188A datasheet, SMC30J188A pinout, SMC30J188A application, or SMC30J188A equivalent, key selection criteria include its 188 V standoff voltage, 0.2 µA leakage at 25 °C, JEDEC-registered SMC package, and IEC 61000-4-2 ±30 kV ESD compliance - all critical for high-reliability overvoltage protection design.

Technical Context

This planar-junction TVS diode uses silicon avalanche technology to provide fast response (<1 ns) to transients while maintaining low dynamic resistance (1963 mΩ) and stable clamping behavior across temperature. Its unidirectional configuration supports DC-biased circuits where reverse conduction must be blocked.

The device meets IEC 61000-4-4 Level 4 (4 kV), exceeds IEC 61000-4-2 Level 4 (±30 kV air/contact discharge), and complies with J-STD-020 MSL Level 1 - confirming suitability for lead-free reflow assembly without moisture sensitivity concerns.

Key Specifications

Pinout & Package

SMC30J188A is housed in a JEDEC-standard SMC (DO-214AB) surface-mount package with matte tin-plated leads, optimized for thermal dissipation on FR4 PCBs with recommended 3.14 cm² copper area per lead. The package measures 7.75–8.15 mm × 5.55–6.25 mm × 2.45 mm max height.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar transient voltage suppression applications.

Compared with SMAJ188A and SMF188A, SMC30J188A uniquely combines 3000 W surge capability, 188 V standoff, and 175 °C operation - making it the sole option among the three qualified for industrial-grade DC bus protection where both energy and thermal robustness are mandatory.

Availability

SMC30J188A is available at Aetrix Electronics and suitable for industrial motor drives, telecom power supplies, solar inverter DC inputs, and automotive on-board chargers requiring stable component supply and long-term lifecycle continuity.

Supply support for SMC30J188A includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in power management, analog, MEMS, and microcontrollers for industrial, automotive, and consumer markets.

SMC30JxxA belongs to ST's high-power TVS diode product line, engineered specifically for ruggedized overvoltage protection in harsh-environment power conversion systems - emphasizing thermal resilience, surge energy handling, and standards-compliant ESD robustness.

FAQ

What is the maximum clamping voltage of SMC30J188A under a 10/1000 µs surge?

The maximum clamping voltage (VCL) is 328 V at 9 A for a 10/1000 µs waveform, measured at 25 °C. This value increases with junction temperature due to the αT coefficient of 10.8 × 10⁻⁴/°C, reaching approximately 345 V at 125 °C junction temperature - a critical factor in thermal design margining.

Is SMC30J188A suitable for bidirectional signal line protection?

No - SMC30J188A is unidirectional and conducts only in reverse bias. For bidirectional protection (e.g., RS-485, USB), the complementary part SMC30J188CA must be used. Using SMC30J188A on AC-coupled or bipolar signal lines risks forward conduction and circuit malfunction.

Does SMC30J188A require derating at elevated ambient temperatures?

Yes - its 3000 W peak pulse power is specified at Tj initial = 25 °C. At 125 °C junction temperature, the derated PPP drops to ~1800 W (per Figure 3), and at 175 °C it falls to ~1200 W. PCB copper area and airflow must be designed to maintain Tj ≤ 150 °C during repeated surge events.

Can SMC30J188A be used in place of SMC30J170A without circuit redesign?

Yes - both share identical SMC package, pinout, and thermal characteristics. However, SMC30J188A has higher VRM (188 V vs. 170 V) and VBR (209 V min vs. 190 V min), resulting in ~19 V higher clamping voltage. Redesign is unnecessary if the protected circuit tolerates this increased clamping level.