Microchip Technology 1N5656

Overview

1N5656 from Microchip (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 73.7 V rated standoff voltage (VWM), 81.9–86.5 V breakdown voltage (V(BR)), 118 V maximum clamping voltage (VC) at 12.7 A peak pulse current (IPP), and 1500 W peak pulse power rating per 10/1000 µs waveform.

For engineers reviewing the 1N5656 datasheet, 1N5656 pinout, 1N5656 application, or 1N5656 equivalent, this device is selected for secondary lightning protection (IEC61000-4-5 Class 1–4), ESD/EFT immunity (IEC61000-4-2/-4), and fast-clamp (<100 ps) suppression of inductive switching transients in harsh-environment power rails and signal lines.

Technical Context

The 1N5656 operates as a unidirectional avalanche diode, entering controlled breakdown above its VWM to clamp transient overvoltages while maintaining low leakage (<5 µA at 73.7 V). 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 peak pulse power with <100 ps response time and exhibits a +0.106 %/°C temperature coefficient of breakdown voltage, enabling predictable clamping behavior under thermal stress. The cathode is internally connected to the metal case, defining polarity and grounding path integrity in PCB layout.

Key Specifications

Pinout & Package

Package: DO-13 (DO-202AA), hermetically sealed metal-glass case with tin-lead plated leads; cathode electrically bonded to case and marked with diode symbol.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N5656, the 1N5656A offers improved V(BR) uniformity for tighter system-level surge margin control, while the SMCJ75A trades hermetic reliability and radiation tolerance for surface-mount manufacturability-making 1N5656 the optimal choice for mission-critical aerospace and defense deployments.

Availability

1N5656 is available at Aetrix Electronics and suitable for aerospace power bus protection, avionics data link interfaces, and railway signaling power supply applications requiring stable component supply, long-lifecycle support, and traceable military-grade sourcing.

Supply support for 1N5656 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 hermetically sealed components for aerospace, defense, and industrial markets.

The 1N5656 belongs to Microchip's legacy TVS diode family originally developed by Microsemi for extreme-environment transient suppression; it was engineered specifically for avionics-grade surge resilience and long-term hermetic reliability in zero-maintenance systems.

FAQ

What is the maximum clamping voltage of the 1N5656 under a 10/1000 µs surge?

The 1N5656 has a maximum clamping voltage (VC) of 118 V when subjected to its rated peak pulse current of 12.7 A under the standard 10/1000 µs waveform. This value is measured at 25°C and represents the highest voltage that will appear across the device during a transient event, directly limiting stress on downstream circuitry. The 1N5656 maintains this clamping performance consistently due to its hermetic DO-13 construction and low dynamic impedance.

Is the 1N5656 suitable for IEC61000-4-5 secondary lightning protection?

Yes, the 1N5656 is explicitly rated for secondary lightning protection per IEC61000-4-5 across multiple classes: Class 1 (42 Ω source) up to 1N5658A, Class 2 (12 Ω) up to 1N5651A, and Class 2 (2 Ω) up to 1N5642A. Its 1500 W peak pulse power and sub-100 ps response enable robust suppression of coupled lightning surges in avionics and rail signaling systems. The 1N5656 itself supports Class 1–4 configurations depending on source impedance and system-level coordination.

Does the 1N5656 have radiation hardness certification?

Yes, the 1N5656 exhibits inherent radiation hardness validated per Microsemi MicroNote 050, a technical note confirming performance stability under total ionizing dose (TID) exposure relevant to low-earth orbit and high-altitude aviation. This characteristic stems from its DO-13 hermetic metal-glass construction and silicon process, making the 1N5656 suitable for space-qualified power conditioning and avionics without supplemental shielding or derating.

What is the thermal resistance of the 1N5656 and how does it affect PCB layout?

The 1N5656 has a junction-to-lead thermal resistance of 50°C/W when measured at 10 mm from the case, and 110°C/W junction-to-ambient on FR4 with 4 mm² copper pads. This means effective heat dissipation relies heavily on direct thermal coupling to a large copper pour or chassis ground plane. For reliable operation at elevated ambient temperatures, PCB layout must minimize lead length and maximize copper area connected to the cathode (case) terminal-critical for sustaining repeated surge events without thermal runaway in the 1N5656.

How does the DO-13 package of the 1N5656 differ from plastic TVS diodes like the 1N6267 series?

The DO-13 package of the 1N5656 is a welded, hermetically sealed metal-glass construction, whereas the 1N6267 series uses plastic axial-leaded packaging. This gives the 1N5656 superior moisture resistance, long-term parameter stability, and mechanical robustness in high-vibration environments-key for aerospace and defense use. Unlike plastic equivalents, the 1N5656's cathode is bonded directly to the case, enabling lower inductance grounding and more predictable clamping behavior, especially critical in fast-transient suppression scenarios.