Vishay General Semiconductor - Diodes Division SMBJ18CAHE3_A/I

Overview

SMBJ18CAHE3_A/I from Vishay General Semiconductor is a bidirectional surface-mount Transient Voltage Suppressor (TVS) diode in SMB (DO-214AA) package, designed for clamping voltage transients on power and signal lines. It features 18 V standoff voltage (V_WM), 20.0–22.1 V breakdown voltage (V_BR) at 1 mA, 600 W peak pulse power (10/1000 µs), 29.2 V maximum clamping voltage (V_C) at 20.5 A, and operates across –55 °C to +150 °C junction temperature range - deployed in industrial sensor interface protection.

For engineers reviewing the SMBJ18CAHE3_A/I datasheet, SMBJ18CAHE3_A/I pinout, SMBJ18CAHE3_A/I application, or SMBJ18CAHE3_A/I equivalent, this device serves as a robust, AEC-Q101-qualified transient suppressor for bidirectional DC bus and communication line protection where low clamping voltage, fast response (<1 ns), and high surge current handling are required.

Technical Context

This TVS diode uses a glass-passivated silicon junction optimized for low incremental surge resistance and excellent clamping ratio (V_C/V_BR ≈ 1.42). Its bidirectional architecture enables symmetrical suppression of positive and negative transients without polarity sensitivity - critical for AC-coupled or floating signal paths.

Thermal design relies on R_θJA = 100 °C/W (typ.) and R_θJL = 20 °C/W (typ.), with derating above 25 °C per Figure 2. It meets MSL Level 1 (JEDEC J-STD-020) and supports lead-free reflow up to 260 °C peak, verified by JESD 22-B102 solderability and JESD 201 Class 2 whisker testing.

Key Specifications

Pinout & Package

Package: SMB (DO-214AA), surface-mount, low-profile case with matte tin-plated leads. Dimensions: 4.57 mm × 3.94 mm × 2.20 mm (L × W × H); cathode band absent (bidirectional type).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ18CAHE3_A/I, SMBJ18CA-E3/52 offers identical electrical performance at lower cost but no automotive qualification, while SMAJ18CAHE3_A/I trades 33 % peak power for 20 % smaller footprint - enabling trade-offs between reliability assurance, surge margin, and PCB area.

Availability

SMBJ18CAHE3_A/I is available at Aetrix Electronics and suitable for industrial sensor interface, automotive body control module, telecom power input stage, and consumer USB-C port protection requiring stable component supply and AEC-Q101 traceability.

Supply support for SMBJ18CAHE3_A/I 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

Vishay General Semiconductor is a global leader in discrete semiconductors, specializing in diodes, MOSFETs, optoelectronics, and passive components with emphasis on reliability and application-specific optimization.

The SMBJ series targets high-energy transient suppression in harsh environments, with design focus on automotive, industrial, and telecom infrastructure where robustness against ESD, EFT, and lightning surges is mandatory.

FAQ

What is the maximum clamping voltage of SMBJ18CAHE3_A/I at its rated peak pulse current?

The SMBJ18CAHE3_A/I has a maximum clamping voltage (V_C) of 29.2 V at its rated peak pulse current (I_PPM) of 20.5 A under the standardized 10/1000 µs waveform. This value is measured per ANSI/IEEE C62.35 and guarantees that downstream circuitry sees no more than 29.2 V during a full 600 W transient event - a key parameter for ensuring compatibility with 3.3 V, 5 V, and 12 V ICs in the protected system.

Is SMBJ18CAHE3_A/I suitable for automotive applications?

Yes, SMBJ18CAHE3_A/I is AEC-Q101 qualified, meaning it has passed rigorous stress tests including high-temperature operating life, temperature cycling, and ESD (HBM ≥ 8 kV). The "HE3" suffix explicitly denotes RoHS-compliant and AEC-Q101-qualified construction, making SMBJ18CAHE3_A/I appropriate for use in automotive body control modules, infotainment systems, and ADAS sensor interfaces where reliability under extended temperature and vibration is required.

How does the bidirectional configuration of SMBJ18CAHE3_A/I affect its PCB layout?

The bidirectional configuration of SMBJ18CAHE3_A/I eliminates polarity marking - there is no cathode band, and both terminals are functionally identical. This allows symmetric placement across differential lines (e.g., RS-485 A/B) or ungrounded rails without orientation constraints. Layout requires only two equal copper pads (0.2" × 0.2") per terminal per Vishay's recommended footprint, simplifying routing and reducing assembly errors compared to unidirectional variants.

What is the thermal resistance from junction to ambient for SMBJ18CAHE3_A/I?

The typical thermal resistance from junction to ambient (R_θJA) for SMBJ18CAHE3_A/I is 100 °C/W when mounted on the minimum recommended pad layout (0.2" × 0.2" copper pads per terminal). This value assumes still air conditions and informs derating calculations: power dissipation must be reduced linearly above 25 °C ambient, per Figure 2 in the Vishay datasheet 88392, to maintain T_J ≤ 150 °C.

Can SMBJ18CAHE3_A/I replace SMBJ18AHE3_A/I in an existing design?

No - SMBJ18CAHE3_A/I is bidirectional, while SMBJ18AHE3_A/I is unidirectional. Their V_BR ranges differ: SMBJ18AHE3_A/I specifies 20.0–22.1 V (same as SMBJ18CAHE3_A/I), but it conducts only in reverse bias and requires correct polarity placement. Substituting without verifying circuit topology may result in unintended conduction or failed protection. Use SMBJ18CAHE3_A/I only where bidirectional clamping is intentionally designed.