Microchip Technology 1N5637A

Overview

1N5637A 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 and industrial systems. It features a 12.1 V rated standoff voltage (VWM), 13.5 V minimum breakdown voltage (V(BR)), 22.0 V maximum clamping voltage (VC) at 68 A peak pulse current, and 1500 W peak pulse power rating per 10/1000 µs waveform - commonly deployed in avionics power rail protection.

For engineers reviewing the 1N5637A datasheet, 1N5637A pinout, 1N5637A application, or 1N5637A equivalent, key selection criteria include its military-grade hermetic DO-13 package, sub-100 ps response time, IEC 61000-4-2/4-4/4-5 compliance for ESD/EFT/secondary lightning, and tight ±5% V(BR) tolerance enabled by the "A" suffix.

Technical Context

The 1N5637A operates as a unidirectional avalanche diode, entering controlled breakdown when reverse voltage exceeds V(BR) = 13.5–14.3 V at I(BR) = 1 mA. Its clamping action limits transients to VC ≤ 22.0 V at IPP = 68 A, delivering 1500 W peak pulse power with thermal resistance of 50°C/W junction-to-lead.

Rated for -55°C to +175°C operation, it uses a cathode-connected-to-case polarity configuration in the DO-13 package and exhibits a temperature coefficient of αV(BR) = 0.084 %/°C - enabling predictable voltage drift across extended temperature ranges in harsh environments.

Key Specifications

Pinout & Package

DO-13 (DO-202AA) hermetically sealed metal-glass package with axial leads; cathode terminal electrically connected to the metal case and marked by a diode symbol on the body.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N5637 and SMCJ12A, the 1N5637A uniquely combines military-grade hermetic packaging, sub-100 ps response, and ±5.9% V(BR) tolerance - making it irreplaceable for avionics and defense systems where failure modes must be eliminated, not merely mitigated.

Availability

1N5637A is available at Aetrix Electronics and suitable for aerospace power distribution, industrial motor drive control, avionics sensor interface, and military vehicle electronics requiring stable component supply under extended temperature and radiation exposure conditions.

Supply support for 1N5637A 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 legacy high-reliability analog and discrete product lines including radiation-hardened and hermetically sealed components.

The 1N5637A belongs to Microchip's legacy TVS diode family originally developed by Microsemi for aerospace and defense applications - engineered specifically for mission-critical surge immunity in extreme environments.

FAQ

What is the maximum clamping voltage of the 1N5637A under standard test conditions?

The 1N5637A has a maximum clamping voltage (VC) of 22.0 V when subjected to a 10/1000 µs peak pulse current of 68 A at TA = 25°C. This value represents the worst-case voltage seen across the device during surge events and is critical for ensuring downstream components remain within absolute maximum ratings. The 1N5637A achieves this clamping performance while maintaining a 12.1 V standoff voltage, providing a robust 9.9 V design margin between normal operation and transient suppression onset.

Is the 1N5637A suitable for IEC 61000-4-5 secondary lightning protection?

Yes, the 1N5637A is explicitly rated for secondary lightning protection per IEC 61000-4-5 with 2 Ω, 12 Ω, and 42 Ω source impedances - supporting Class 1 through Class 4 depending on source impedance. At 42 Ω, it meets Class 1; at 12 Ω, Class 1; and at 2 Ω, Class 2. Its 1500 W peak pulse power rating and 22.0 V clamping voltage ensure compliance without external series impedance. The 1N5637A's hermetic DO-13 package further enhances reliability in field-deployed systems subject to repeated surge exposure.

Does the 1N5637A have military qualification options?

Yes, the "A" suffix in 1N5637A indicates compliance with tighter parametric tolerances and screening per MIL-PRF-19500/500. When prefixed with JANTXV (e.g., JANTXV1N5637A), it becomes a fully qualified high-reliability part meeting QML-38534 requirements for space and defense applications. The 1N5637A itself serves as the baseline for these qualified variants and shares identical electrical characteristics, DO-13 packaging, and hermetic construction - making it suitable for programs requiring traceable, screened components.

How does the 1N5637A differ from the commercial-grade 1N5637?

The 1N5637A differs from 1N5637 primarily in tighter V(BR) tolerance (13.5–14.3 V vs. 13.5–16.5 V), lower standby current (5 µA vs. 500 µA at VWM), and eligibility for military screening. These differences make the 1N5637A more predictable in precision clamping applications and better suited for low-power, high-reliability systems. While both share the same DO-13 package and 1500 W rating, only the 1N5637A supports JANTXV qualification and radiation-hardened deployment - confirming its role as the preferred variant for aerospace and defense use of the 1N5637A.

What is the thermal resistance specification for the 1N5637A?

The 1N5637A has a thermal resistance of 50°C/W junction-to-lead when measured at 0.375 inches (10 mm) from the case body, and 110°C/W junction-to-ambient when mounted on an FR4 PCB with 4 mm² copper pads (1 oz), 1 mm track width, and 25 mm length. This dual specification allows accurate thermal modeling in both lead-soldered and PCB-mounted configurations. The low junction-to-lead Rθ enables effective heat transfer to chassis ground via the cathode-connected case - a key advantage of the DO-13 package used in the 1N5637A.