Vishay General Semiconductor - Diodes Division SMBJ8.0CAHM3/H

Overview

SMBJ8.0CAHM3/H from Vishay General Semiconductor is a bidirectional surface-mount transient voltage suppressor (TVS) diode in SMB (DO-214AA) package, designed for clamping ESD and surge transients on signal/power lines. It features 8.0 V stand-off voltage (V_WM), 600 W peak pulse power (10/1000 µs), 13.6 V maximum clamping voltage (V_C) at 44.1 A IPPM, and operates across -55 °C to +150 °C junction temperature range - deployed in industrial sensor interfaces and telecom line protection.

For engineers reviewing the SMBJ8.0CAHM3/H datasheet, SMBJ8.0CAHM3/H pinout, SMBJ8.0CAHM3/H application, or SMBJ8.0CAHM3/H equivalent, key selection criteria include bidirectional clamping capability, low V_C/V_WM ratio (1.7×), halogen-free RoHS-compliant construction (HM3 suffix), AEC-Q101 qualification readiness, and compatibility with automated SMT placement on 5.0 mm × 5.0 mm copper pads.

Technical Context

This device functions as a voltage-clamping protector using an avalanche breakdown mechanism, with symmetrical bidirectional behavior enabling suppression of both positive and negative transients without polarity sensitivity. Its glass-passivated junction ensures stable breakdown characteristics and low leakage (<1.0 µA at V_WM), while MSL Level 1 rating supports lead-free reflow up to 260 °C peak.

The SMBJ8.0CAHM3/H delivers 44.1 A peak pulse current (I_PPM) under 10/1000 µs waveform, with thermal resistance R_θJA = 100 °C/W and R_θJL = 20 °C/W - confirming suitability for board-level surge protection where localized heat dissipation via PCB copper is critical. It meets UL 497B recognition (QVGQ2) for telecom and industrial protectors.

Key Specifications

Pinout & Package

Package: SMB (DO-214AA), surface-mount, bidirectional - no polarity marking; symmetrical terminals function as interchangeable anode/cathode pair.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ8.0CAHM3/H, the E3 variant trades halogen-free compliance for lower unit cost, while the SMCJ8.0CAHM3 offers 2.5× higher surge capacity at the expense of 2.5× larger PCB area - making SMBJ8.0CAHM3/H optimal for space-constrained, environmentally regulated industrial and automotive-adjacent designs.

Availability

SMBJ8.0CAHM3/H is available at Aetrix Electronics and suitable for industrial sensor interfaces, telecom line protection, and automotive body control modules requiring stable component supply, halogen-free compliance, and AEC-Q101 qualification readiness.

Supply support for SMBJ8.0CAHM3/H 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, rectifiers, MOSFETs, and protection devices with emphasis on reliability, efficiency, and application-specific optimization.

The SMBJ series is engineered for robust transient suppression in harsh environments - targeting industrial automation, telecom infrastructure, and automotive subsystems where compact size, high surge tolerance, and long-term stability are critical.

FAQ

What does the 'HM3' suffix indicate for SMBJ8.0CAHM3/H?

The HM3 suffix denotes halogen-free, RoHS-compliant construction with matte tin-plated leads meeting JESD 201 Class 2 whisker resistance. It also signals qualification path alignment with AEC-Q101 for automotive applications - distinct from E3 (RoHS only) or HE3 (AEC-Q101 + RoHS) variants. SMBJ8.0CAHM3/H maintains full electrical equivalence to other SMBJ8.0CA versions while satisfying stricter environmental and reliability mandates.

Is SMBJ8.0CAHM3/H suitable for protecting USB or HDMI signal lines?

No - SMBJ8.0CAHM3/H is not optimized for high-speed digital interfaces. Its typical junction capacitance exceeds 100 pF at 0 V bias, which would distort signal integrity above ~10 MHz. For USB 2.0 or HDMI, low-capacitance TVS arrays (e.g., <0.5 pF) are required. SMBJ8.0CAHM3/H is intended for lower-frequency power/signal lines such as RS-485, CAN, or 24 V DC inputs where clamping voltage and surge energy handling are prioritized over bandwidth.

How does SMBJ8.0CAHM3/H perform under repeated surge stress?

SMBJ8.0CAHM3/H supports repetitive 10/1000 µs surges at 0.01% duty cycle without parameter degradation, validated per JEDEC standards. Its glass-passivated junction and thermal resistance profile (R_θJA = 100 °C/W) ensure stable clamping performance across 1000+ surge events when mounted on minimum 5.0 mm × 5.0 mm copper pads. Real-world validation shows <5% V_C drift after 1000 cycles at rated I_PPM.

Can SMBJ8.0CAHM3/H replace unidirectional SMBJ8.0A in existing designs?

No direct replacement - SMBJ8.0CAHM3/H is bidirectional with symmetrical clamping, while SMBJ8.0A is unidirectional and conducts forward current. Substituting them requires verifying circuit topology: bidirectional use demands no DC bias across the device, whereas unidirectional types rely on polarity-aware placement. Using SMBJ8.0CAHM3/H in place of SMBJ8.0A may cause unintended conduction if DC voltage is present, risking overheating or failure.

What is the maximum allowable PCB trace length between SMBJ8.0CAHM3/H and protected IC?

To maintain effective clamping, PCB trace inductance must be minimized - recommended trace length is ≤5 mm per leg (input and ground) with ≥0.5 mm width and solid ground plane underneath. Longer traces add inductance that elevates overshoot voltage (V = L·di/dt); for SMBJ8.0CAHM3/H's 44.1 A I_PPM and typical di/dt of 10⁹ A/s, every 1 nH adds ~1 V overshoot. Layout best practice uses direct placement adjacent to connector or IC pins, with dedicated ground pour connected via multiple vias.