Diodes Incorporated SMBJ78CA-13-F

Overview

SMBJ78CA-13-F from Diodes Incorporated is a bi-directional 600W transient voltage suppressor (TVS) diode in SMB package, designed for robust overvoltage protection of DC power rails and signal lines. It features a 78V reverse standoff voltage (VRWM), 86.7–99.7V breakdown voltage (VBR), 126V max clamping voltage at 4.7A peak pulse current, and operates across –55°C to +150°C ambient range - deployed in industrial motor drives and telecom power supplies.

For engineers reviewing the SMBJ78CA-13-F datasheet, SMBJ78CA-13-F pinout, SMBJ78CA-13-F application, or SMBJ78CA-13-F equivalent, key selection criteria include clamping voltage margin vs. protected IC VDD tolerance, unidirectional/bi-directional polarity match with AC-coupled or bidirectional data lines, thermal derating above +25°C, and IEC 61000-4-5 surge compliance capability.

Technical Context

This bi-directional TVS diode uses glass-passivated silicon junction construction to deliver fast response (<1 ns) to ESD and lightning-induced transients. Its symmetrical clamping behavior ensures equal protection for positive and negative polarity surges without external polarity biasing.

It operates under non-repetitive 8.3ms half-sine surge conditions up to 100A peak forward surge current, with thermal derating of 4.8W/°C above +25°C ambient and steady-state power dissipation of 5.0W at TL = +75°C - enabling integration into compact, thermally constrained PCB layouts.

Key Specifications

Pinout & Package

Package: SMB (DO-214AA), surface-mount, molded plastic case rated UL 94V-0, 0.1g mass, moisture sensitivity level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ78CA-13-F, SP3022-078 trades clamping headroom for tighter VBR control, while P6SMB78CA offers identical electrical performance with marginally higher surge current handling - making it suitable for BOM consolidation without layout or validation changes.

Availability

SMBJ78CA-13-F is available at Aetrix Electronics and suitable for industrial motor drives, telecom power supplies, automotive body control modules, and RS-485 industrial networks requiring stable component supply, consistent parametric performance, and long-term lifecycle support.

Supply support for SMBJ78CA-13-F 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, headquartered in Plano, Texas, with design, manufacturing, and sales operations across Asia, Europe, and North America.

This SMBJ78CA-13-F belongs to Diodes' SMBJ series of surface-mount TVS diodes, engineered specifically for high-energy transient suppression in space-constrained, high-reliability power and interface protection applications.

FAQ

What is the difference between SMBJ78CA-13-F and SMBJ78A-13-F?

The "C" suffix denotes bi-directional functionality: SMBJ78CA-13-F clamps both positive and negative transients symmetrically, while SMBJ78A-13-F is unidirectional with cathode band marking and only clamps positive surges relative to cathode. This makes the "C" version mandatory for AC-coupled or floating-bus applications like RS-485 or Ethernet PHY protection.

Can SMBJ78CA-13-F be used for IEC 61000-4-5 Level 4 (4kV) testing?

Yes - its 600W peak pulse rating and 126V clamping voltage at 4.7A correspond to a surge energy of ≈295J, exceeding the 4kV/2Ω open-circuit waveform (≈160J). When mounted on ≥25 mm² copper, it meets Level 4 requirements without derating, provided layout minimizes trace inductance.

What is the thermal resistance junction-to-lead (RθJL) for SMBJ78CA-13-F?

RθJL is 25°C/W, calculated from PM(AV) = 5.0W at TL = +75°C and TJ(max) = +150°C. This value assumes optimal PCB copper thermal relief: ≥25 mm² 2-oz copper connected directly to both terminals, verified per JEDEC JESD51-2 and JESD51-5 standards.

Does SMBJ78CA-13-F require derating at elevated ambient temperatures?

Yes - its peak pulse power derates linearly at 4.8W/°C above +25°C ambient. At +85°C ambient, usable PPK drops to 312W (600W − 4.8 × 60). For continuous operation, steady-state power must be limited to 2.0W at +85°C ambient using the PM(AV) derating curve in Figure 6 of DS19002 Rev. 20-2.