Taiwan Semiconductor Corporation SMCJ85C

Overview

SMCJ85C from Taiwan Semiconductor is a unidirectional 1500W surface-mount transient voltage suppressor (TVS) diode in DO-214AB (SMC) package, with 85V working stand-off voltage (VWM), 94.4–115V breakdown voltage (VBR), and 151V maximum clamping voltage (VC) at 10.4A peak pulse current-designed for automotive power line surge protection per ISO 7637-2 Pulse 1/2a/2b/3a/3b.

For engineers reviewing the SMCJ85C datasheet, SMCJ85C pinout, SMCJ85C application, or SMCJ85C equivalent, key selection criteria include clamping performance under 10/1000μs surge, junction temperature derating above 25°C, unidirectional polarity marking, and compatibility with automated SMT placement on 12V/24V vehicle subsystems.

Technical Context

The SMCJ85C employs a glass-passivated silicon junction optimized for fast transient response (<1.0 ps rise to VBR), low leakage (<1 μA at 85V), and robust energy handling (1500W peak, 5W steady-state). Its thermal design delivers R_θJA = 55°C/W and R_θJC = 10°C/W, enabling reliable operation up to T_J = +150°C in constrained PCB layouts.

As a unidirectional TVS, it conducts only during reverse overvoltage events-blocking forward conduction until VF ≈ 3.5V (per spec note for SMCJ5.0–SMCJ90 devices). It meets JESD201 Class 2 whisker resistance and UL 94V-0 flammability requirements for automotive-grade assemblies.

Key Specifications

Pinout & Package

DO-214AB (SMC) surface-mount package with cathode band marking on one end; two-terminal device with polarity-sensitive mounting-cathode side must align with circuit ground reference for proper unidirectional clamping.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ85CA and SMCJ85A, the SMCJ85C provides optimal balance of surge robustness, unidirectional precision, and manufacturing scalability-making it preferred for automotive body control modules and industrial 24V sensor inputs where polarity is fixed and cost-per-unit matters.

Availability

SMCJ85C is available at Aetrix Electronics and suitable for automotive electronics, industrial PLCs, LED lighting systems, and telecom power interfaces requiring stable component supply and full traceability through production lifecycles.

Supply support for SMCJ85C 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

Taiwan Semiconductor Corporation (TSC) is a vertically integrated analog and discrete semiconductor manufacturer headquartered in Hsinchu, Taiwan, specializing in TVS diodes, rectifiers, MOSFETs, and power management components since 1979.

The SMCJ series was engineered specifically for high-energy automotive and industrial surge immunity-emphasizing ISO 7637-2 compliance, tight thermal resistance, and automated assembly readiness in DO-214AB packaging.

FAQ

What is the clamping voltage of the SMCJ85C under a standard 10/1000μs surge?

The SMCJ85C has a maximum clamping voltage (VC) of 151 V when subjected to a 10.4 A peak pulse current with a 10/1000μs waveform. This value is measured per Fig.5 in the official datasheet and ensures downstream components see no more than 151 V during standardized surge events-critical for protecting 12V/24V system ICs with ≤16 V absolute maximum ratings. The SMCJ85C maintains this performance across its full operating temperature range.

Is the SMCJ85C unidirectional or bidirectional, and how is polarity identified?

The SMCJ85C is a unidirectional TVS diode, indicated by the absence of "CA" in its part number. Polarity is marked by a cathode band on the DO-214AB package-this band must be oriented toward the system ground reference to ensure correct clamping behavior. Unlike bidirectional variants (e.g., SMCJ85CA), the SMCJ85C blocks forward current until ~3.5 V and only clamps reverse overvoltages above its 85 V stand-off threshold.

Does the SMCJ85C meet automotive surge immunity standards?

Yes, the SMCJ85C meets ISO 7637-2 requirements for Pulses 1, 2a, 2b, 3a, and 3b-covering common automotive transients such as load dump, inductive switching, and capacitive coupling. Its 1500 W peak power rating, fast <1.0 ps response time, and validated clamping performance make it suitable for engine control units, body control modules, and infotainment power supplies. The SMCJ85C is not rated for Pulse 5a (load dump) alone-system-level design must include additional filtering.

What is the maximum junction temperature and thermal resistance of the SMCJ85C?

The SMCJ85C has a maximum junction temperature (T_J) of +150°C and thermal resistances of R_θJA = 55°C/W (junction-to-ambient) and R_θJC = 10°C/W (junction-to-case). These values allow direct thermal modeling in PCB layouts with copper pour and heatsinking. Derating begins above 25°C ambient per Fig.2 in the datasheet-ensuring safe operation in under-hood environments when mounted on ≥1 in² 2-oz copper.

How does the SMCJ85C differ from the SMCJ85A variant?

The SMCJ85C and SMCJ85A share identical VWM (85 V), package (DO-214AB), and peak power (1500 W), but differ in VBR tolerance and clamping voltage: SMCJ85A has tighter VBR (94.4–104 V) and lower VC (137 V @ 11.5 A), while SMCJ85C specifies VBR up to 115 V and VC up to 151 V. This makes SMCJ85A preferable for designs needing tighter clamping margins; SMCJ85C offers broader process tolerance for high-volume cost-sensitive applications. Both are unidirectional and pin-compatible.