STMicroelectronics STIEC45-26AS

Overview

STIEC45-26AS from STMicroelectronics is a unidirectional Transil™ TVS diode designed for IEC 61000-4-5 surge protection on DC power lines, with 26 V stand-off voltage (VRM), 45 V max clamping voltage at 500 A (8/20 μs), and 150 °C max operating junction temperature. It delivers 500 A peak pulse current capability and supports high-reliability SMPS and industrial power supplies requiring low leakage (0.2 μA at 25 °C) and robust ESD/EFT immunity.

For engineers reviewing the STIEC45-26AS datasheet, STIEC45-26AS pinout, STIEC45-26AS application, or STIEC45-26AS equivalent, key selection criteria include clamping performance at 500 A, thermal resistance (Rth(j-l) = 15 °C/W), unidirectional polarity behavior, SMC package footprint compatibility, and compliance with IEC 61000-4-2 Level 4 (8 kV contact discharge) and MIL-STD-883H Class 3B (25 kV HBM).

Technical Context

The STIEC45-26AS operates as a voltage-clamping transient suppressor in series with DC power rails, triggering conduction above its 28.9 V (min) breakdown voltage (VBR) and limiting residual voltage to ≤45 V under 500 A 8/20 μs surges. Its planar silicon structure enables stable performance up to 150 °C junction temperature while maintaining sub-1 μA leakage at 85 °C.

It meets IEC 61000-4-5 Level 4 (4 kV common-mode, 12 Ω source) and Level 2 (1 kV differential-mode, 2 Ω source), with dynamic resistance (RD) of 0.026 Ω enabling precise clamping voltage prediction via VCL = RD × IPP + VBR(max). The device uses JEDEC DO-214AB (SMC) packaging with IPC 7351-compliant footprint and UL 94 V0 resin encapsulation.

Key Specifications

Pinout & Package

The STIEC45-26AS is housed in an SMC (DO-214AB) surface-mount package per JEDEC standards, with 2 terminals and recommended pad layout per IPC 7351. Thermal resistance is 15 °C/W (junction-to-leads) and 90 °C/W (junction-to-ambient on specified copper area).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ26A and P6SMB26A, the STIEC45-26AS offers superior thermal robustness (150 °C Tj), lower clamping voltage (45 V vs ≥49.9 V), and better thermal resistance-making it preferred for high-reliability, high-temperature power rail protection where sustained surge duty cycles occur.

Availability

STIEC45-26AS is available at Aetrix Electronics and suitable for industrial PLC power inputs, telecom DC feeds, server PSU hold-up circuits, and automotive body control modules requiring stable component supply and full IEC 61000-4-5 compliance.

Supply support for STIEC45-26AS 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in power management, analog, MEMS, and microcontrollers for industrial, automotive, and consumer markets.

The STIEC45 series belongs to ST's Transil™ TVS portfolio, engineered specifically for high-energy surge immunity in DC power infrastructure-emphasizing low leakage, high-temperature reliability, and precise clamping for mission-critical power rails.

FAQ

What is the maximum clamping voltage of STIEC45-26AS at 300 A (8/20 μs)?

The clamping voltage scales linearly with current using VCL = VBR(max) + RD × IPP. With VBR(max) = 31.9 V and RD = 0.026 Ω, VCL at 300 A is 31.9 + (0.026 × 300) = 39.7 V. This value is consistent with the device's 45 V max rating at 500 A and confirms predictable suppression behavior across surge magnitudes.

Can STIEC45-26AS be used in bidirectional signal line protection?

No. STIEC45-26AS is unidirectional and conducts only in reverse bias above VBR; forward conduction begins near 0.6 V, making it unsuitable for AC or bidirectional data lines. For bidirectional protection, ST recommends the pin-compatible STIEC45-26ACS variant, which clamps symmetrically in both directions with identical VBR and VCL characteristics.

How does the 150 °C maximum junction temperature affect PCB layout?

The 150 °C rating allows placement near heat-generating components, but thermal performance depends on copper area. The datasheet specifies a 90 °C/W junction-to-ambient resistance on a recommended pad layout (FR4, 35 µm Cu, defined copper surface per lead). Reducing copper area increases thermal resistance and may require derating Ipp or adding thermal vias to maintain safe Tj under repeated surges.

Is STIEC45-26AS compliant with RoHS2 and REACH?

Yes. The device is RoHS2 compliant (2011/65/EU) and meets REACH SVHC requirements per ST's ECOPACK® environmental program. Its UL 94 V0 resin, lead-free terminations, and halogen-free construction are documented in ST's official product compliance statements and supported by material declarations available through ST's quality portal.