Microchip Technology MS1N8178US/TR

Overview

MS1N8178US/TR from Microsemi is a voidless-hermetically-sealed unidirectional transient voltage suppressor (TVS) with 4 pF capacitance, 124 V working standoff voltage (VWM), and 150 W peak pulse power at 10/1000 µs. It features internal Category 1 metallurgical bonds and is designed for high-reliability ESD/EFT protection in RF front-ends and aerospace data links.

For engineers reviewing the MS1N8178US/TR datasheet, MS1N8178US/TR pinout, MS1N8178US/TR application, or MS1N8178US/TR equivalent, this device delivers verified low-capacitance transient suppression for 124 V DC systems requiring IEC61000-4-2 Level 4 and IEC61000-4-4 compliance without signal integrity degradation.

Technical Context

The MS1N8178US/TR integrates a series-opposed rectifier diode to achieve 4 pF total capacitance - the lowest among 150 W TVS devices in its voltage class. Its clamping voltage is 183 V at 300 A IPP under 10/1000 µs waveform, with a temperature coefficient of breakdown voltage of 0.107 %/°C.

Constructed in hard-glass hermetic package with tungsten slugs and RoHS-compliant matte tin plating, it supports operation from –55 °C to +175 °C junction temperature and exhibits <0.5 µA standby current at rated VWM, enabling use in low-power always-on protection circuits.

Key Specifications

Pinout & Package

MS1N8178US/TR uses an axial-leaded "A" package (hard-glass hermetic case with tungsten slugs), cathode-banded polarity, and weighs ~340 mg. Leads are RoHS-compliant matte tin over copper.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMCJ120A and 1N6372, the MS1N8178US/TR uniquely combines hermetic reliability, 4 pF capacitance, and 124 V VWM - making it irreplaceable in RF-critical, high-temperature, or mission-critical systems where parameter stability and long-term seal integrity are mandatory.

Availability

MS1N8178US/TR is available at Aetrix Electronics and suitable for avionics data link protection, satellite telemetry receiver front-ends, and downhole oilfield sensor interfaces requiring stable component supply across extended product lifecycles.

Supply support for MS1N8178US/TR 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

Microsemi Corporation (now part of Microchip Technology) is a U.S.-based semiconductor company specializing in high-reliability analog and mixed-signal ICs, radiation-hardened components, and precision timing solutions.

The MS1N8178US/TR belongs to Microsemi's legacy 1N81xx series of hermetic TVS diodes, engineered specifically for defense, aerospace, and industrial systems demanding zero-failure transient protection under extreme thermal, mechanical, and radiation stress.

FAQ

What is the clamping voltage of the MS1N8178US/TR at its rated peak impulse current?

The MS1N8178US/TR has a maximum clamping voltage (VC) of 183 V at 300 A peak impulse current (IPP) under the standard 10/1000 µs waveform. This value is measured per Microsemi T4-LDS-xxxx specification and defines the upper voltage limit imposed on protected circuitry during a full-rated surge event. The MS1N8178US/TR maintains this clamping performance across its full operating temperature range.

Is the MS1N8178US/TR suitable for bidirectional transient protection?

The MS1N8178US/TR is a unidirectional TVS diode and requires anti-parallel pairing with an identical unit to achieve bidirectional protection. Microsemi's datasheet explicitly recommends this configuration (Figure 5) for applications like MIL-STD-1553B buses. When used this way, the combined capacitance is 8 pF - still among the lowest available for 150 W bidirectional TVS solutions - and the MS1N8178US/TR retains its full 150 W surge rating per device.

Does the MS1N8178US/TR meet space-level reliability standards?

Yes. The MS1N8178US/TR incorporates internal Category 1 metallurgical bonds and voidless hermetic glass packaging, both qualified per MIL-PRF-19500 and referenced in Microsemi MicroNote 050 for inherent radiation hardness. Its construction supports spaceflight qualification when integrated into properly screened assemblies, and the MS1N8178US/TR is commonly used in LEO satellite telemetry chains where single-event burnout resistance is required.

What is the thermal resistance and steady-state power rating of the MS1N8178US/TR?

The MS1N8178US/TR has a thermal resistance junction-to-ambient (RθJA) of 150 °C/W and a steady-state average power rating (PM(AV)) of 1.0 W at TA = 25 °C. This rating assumes adequate PCB thermal management; exceeding TJ(MAX) = +175 °C will degrade long-term reliability. The MS1N8178US/TR is not intended for continuous power dissipation but for transient-only suppression - its 150 W peak pulse rating applies only to short-duration impulses.

How does the 4 pF capacitance of the MS1N8178US/TR compare to standard TVS diodes in the same power class?

The 4 pF capacitance of the MS1N8178US/TR is the lowest published value among all 150 W TVS diodes in its voltage range (120–130 V VWM). Standard alternatives such as the 1N6372 or SMBJ120A typically measure 10–15 pF. This 2.5× reduction preserves signal integrity in RF and high-speed digital paths - for example, enabling use on 2.2 GHz telemetry receiver inputs where even 6 pF would cause measurable insertion loss - a key differentiator confirmed in Microsemi's T4-LDS-xxxx characterization.