Diodes Incorporated SMF4L51CAQ-7

Overview

SMF4L51CAQ-7 from Diodes Incorporated is a bi-directional transient voltage suppressor (TVS) diode in DO-219AA package, rated for 400W peak pulse power (10/1000µs), 51V working peak reverse voltage (VRWM), 82.4V maximum clamping voltage (VC) at 4.9A surge current, and AEC-Q101 qualified for automotive battery line protection.

For engineers reviewing the SMF4L51CAQ-7 datasheet, SMF4L51CAQ-7 pinout, SMF4L51CAQ-7 application, or SMF4L51CAQ-7 equivalent, key selection criteria include clamping performance under ISO 7637-2 Pulse 1/2a/5a, bidirectional ESD robustness (±30kV IEC61000-4-2), thermal resistance (RθJA = 96°C/W), and compatibility with 12V/24V automotive power rails.

Technical Context

This bi-directional TVS operates symmetrically across both polarities to clamp transients on unidirectional or AC-coupled lines without polarity dependency. Its silicon avalanche structure delivers sub-5ns response time from 0V to breakdown, enabling suppression of fast-rising load dump and inductive switching spikes.

Designed for surface-mount integration in space-constrained automotive ECUs and infotainment systems, it uses a low-inductance DO-219AA package with cathode-band-free marking and matte tin terminals compatible with lead-free reflow profiles. Thermal design relies on PCB copper area for junction-to-ambient dissipation (RθJA = 96°C/W).

Key Specifications

Pinout & Package

Package: DO-219AA - ultra-low-profile (max height 0.75mm), molded green plastic (UL 94V-0), 2-terminal SMD device with no polarity marking for bi-directional operation. Terminals are matte tin over copper alloy, solderable per MIL-STD-202 Method 208.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bi-directional TVS diode applications.

Compared with SMAJ51CA and TPSMD51C, SMF4L51CAQ-7 delivers identical 400W surge capability in a 60% smaller footprint and 70% lower profile, enabling direct replacement in space-limited automotive modules without thermal or electrical compromise.

Availability

SMF4L51CAQ-7 is available at Aetrix Electronics and suitable for automotive electronics, battery management systems, and industrial control panels requiring stable component supply with AEC-Q101 compliance and PPAP documentation support.

Supply support for SMF4L51CAQ-7 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.

The SMF4L series belongs to Diodes' AEC-Q101-qualified TVS portfolio, engineered specifically for automotive power line and data line transient suppression with emphasis on miniaturization, ESD hardness, and thermal efficiency in DO-219AA packaging.

FAQ

What is the maximum clamping voltage of SMF4L51CAQ-7 at its rated peak pulse current?

The maximum clamping voltage (VC) is 82.4V at 4.9A peak pulse current (IRSM), measured using the 10/1000µs standard waveform. This value is guaranteed across the full operating temperature range (−55°C to +175°C) and defines the upper voltage limit imposed on protected circuitry during surge events.

Is SMF4L51CAQ-7 suitable for protecting CAN FD bus lines?

No - SMF4L51CAQ-7 is not optimized for CAN FD due to its 51V VRWM and 82.4V VC, which exceed typical CAN FD common-mode voltage limits (±40V). Its capacitance (≈100pF at 1MHz) also risks signal integrity degradation at 5Mbps. Use dedicated low-capacitance CAN TVS like D3V3F4U2UP instead.

How does the DO-219AA package affect thermal performance compared to SMA or SMB packages?

The DO-219AA package achieves RθJA = 96°C/W with a 1"×1" 2oz Cu pad - 24°C/W lower than SMA (120°C/W) and 18°C/W lower than SMB (114°C/W) under identical conditions. Its low profile (0.75mm max height) and wide thermal pad contact area improve heat spreading to the PCB, enabling higher sustained surge duty cycles.

Does SMF4L51CAQ-7 require derating for operation above +25°C ambient temperature?

Yes - peak pulse power must be linearly derated above +25°C per Figure 1 in DS43393 Rev. 3-2. At +85°C ambient, maximum PPK drops to 240W (60% of 400W). Derating applies to both single-pulse and repetitive surge conditions, and steady-state power dissipation is limited to 1.0W regardless of temperature.