Microchip Technology 1N5644

Overview

1N5644 from Microchip Technology (formerly Microsemi) is a unidirectional transient voltage suppressor (TVS) diode in a hermetically sealed DO-13 metal package, designed for high-reliability surge protection in aerospace, avionics, and industrial systems. It features a 24.3 V minimum breakdown voltage (V_BR), 21.8 V rated standoff voltage (V_WM), 43.5 V maximum clamping voltage (V_C) at 34.5 A peak pulse current (I_PP), and 1500 W peak pulse power rating at 10/1000 µs waveform.

For engineers reviewing the 1N5644 datasheet, 1N5644 pinout, 1N5644 application, or 1N5644 equivalent, this device is selected for secondary lightning protection per IEC 61000-4-5 (with 2 Ω, 12 Ω, and 42 Ω source impedances), ESD/EFT immunity per IEC 61000-4-2/-4-4, and fast-response (<100 ps) suppression of inductive switching transients in harsh environments.

Technical Context

The 1N5644 operates as a unidirectional avalanche diode, entering controlled breakdown when reverse voltage exceeds its V_WM (21.8 V) to clamp transient energy. Its hermetic DO-13 package ensures stable performance across -55°C to +175°C operating temperature range and inherent radiation hardness per MicroNote 050.

It delivers 1500 W non-repetitive peak pulse power with <100 ps response time, enabling protection against ESD, EFT, and induced RF transients. The cathode is internally connected to the metal case, defining polarity and thermal path - critical for mounting on heatsinked chassis or grounded planes.

Key Specifications

Pinout & Package

1N5644 uses a two-terminal DO-13 (DO-202AA) axial-leaded metal package with cathode connected to the case. Polarity is marked by a diode symbol on the body; lead 1 (cathode) is electrically tied to the case and must be mounted to a grounded or low-impedance heat-sinking surface.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N5644, the 1N5644A offers tighter parametric control and military qualification eligibility, while SMBJ24A trades hermeticity, power handling, and temperature range for SMT compatibility and lower cost - making it unsuitable for avionics or high-reliability industrial use.

Availability

1N5644 is available at Aetrix Electronics and suitable for aerospace power bus protection, industrial motor drive control, military vehicle electronics, and telecom line interface applications requiring stable component supply, long-lifecycle support, and traceable sourcing.

Supply support for 1N5644 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

Microchip Technology acquired Microsemi in 2018 and maintains its high-reliability analog and discrete product portfolio, including radiation-hardened and military-qualified components for defense, aerospace, and industrial markets.

The 1N5644 belongs to Microchip's legacy TVS diode family originally developed by Microsemi for mission-critical surge protection. It was engineered specifically for systems demanding hermetic packaging, extreme temperature resilience, and compliance with MIL-PRF-19500 and IEC 61000-4-x standards.

FAQ

What is the maximum clamping voltage of the 1N5644 under a 10/1000 µs surge?

The 1N5644 has a maximum clamping voltage (V_C) of 43.5 V when subjected to its rated peak pulse current of 34.5 A under the standard 10/1000 µs waveform. This value is measured at T_A = 25°C and defines the upper voltage limit imposed on protected circuitry during surge events - critical for ensuring downstream ICs remain within absolute maximum ratings.

Is the 1N5644 suitable for bidirectional transient protection?

No, the 1N5644 is a unidirectional TVS diode and conducts only in reverse breakdown. It must be used with correct polarity - anode to line, cathode to ground - and cannot suppress positive-going transients on AC or bipolar signals. For bidirectional protection in the same DO-13 package, Microchip specifies the 1N6036–1N6072A series, which are explicitly designed for symmetrical clamping.

Does the 1N5644 require a heatsink for normal operation?

The 1N5644 does not require an external heatsink for transient suppression duty, as it is not intended for continuous power dissipation. Its 1 W DC power rating applies only at T_L ≤ +125°C with 3/8″ lead length. However, its metal case must be mechanically and electrically attached to a grounded chassis or copper pour to ensure low-inductance return path and effective thermal transfer during high-current pulses.

What is the standoff voltage rating of the 1N5644, and how is it used in circuit design?

The 1N5644 has a rated standoff voltage (V_WM) of 21.8 V, meaning it remains non-conductive up to this reverse voltage at 25°C. In circuit design, V_WM must be ≥ the maximum continuous operating voltage of the protected line - e.g., for a 24 V nominal system with 10% tolerance (26.4 V max), 1N5644 is not suitable; a higher-V_WM variant like 1N5647 (31.6 V) would be required.

Can the 1N5644 be used for ESD protection per IEC 61000-4-2?

Yes, the 1N5644 is explicitly qualified for ESD protection per IEC 61000-4-2 due to its sub-100 ps response time and robust clamping behavior. Its 43.5 V clamping voltage at 34.5 A ensures protection of sensitive inputs even under ±8 kV contact discharge, provided layout minimizes trace inductance between the device and protected node - a key requirement confirmed in Microsemi application guidance.