Microchip Technology 1PMT5945A/TR7

Overview

1PMT5945A/TR7 from Microsemi is a 68 V, ±5% tolerance surface-mount Zener diode in the Powermite® package, rated for 3.0 W DC power dissipation at TAB 1 = 60°C, with 120 Ω dynamic impedance at 5.5 mA test current and 1700 µA max reverse leakage at 51.2 V. It serves as a precision voltage reference or overvoltage clamp in DC power rails of industrial control modules.

For engineers reviewing the 1PMT5945A/TR7 datasheet, 1PMT5945A/TR7 pinout, 1PMT5945A/TR7 application, or 1PMT5945A/TR7 equivalent, key selection criteria include zener voltage accuracy, thermal resistance (30°C/W junction-to-TAB), ESD rating (>16 kV HBM), low knee impedance (≤1700 Ω at IZK), and compatibility with automated SMT placement equipment.

Technical Context

This Zener diode operates in reverse breakdown mode with a nominal zener voltage of 68 V measured at 5.5 mA (IZT) with TAB temperature held at 30°C. Its Powermite® package features a full metallic bottom and integral locking tab that functions as both mechanical anchor and heat sink, enabling direct thermal conduction from junction to PCB copper.

The device exhibits 120 Ω dynamic impedance (ZZT) at IZT and maintains ≤1700 µA reverse leakage (IR) at VR = 51.2 V - a value derived from the 75% of VZ specification per standard Zener characterization practice. Thermal resistance is fixed at 30°C/W from junction to TAB 1, confirming its suitability for thermally constrained layouts where TAB 1 is soldered to a thermal pad.

Key Specifications

Pinout & Package

Package: Powermite® - surface-mount molded package with full metallic bottom and integral locking tab; cathode designated by TAB 1; weight ≈ 0.016 g; compatible with EIA-481 tape-and-reel (7″ reel: 3,000 pcs).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMCJ68A and 1N5365B, the 1PMT5945A/TR7 uniquely combines SMT compatibility, 30°C/W thermal resistance, and 120 Ω dynamic impedance - making it optimal for space-constrained, thermally demanding Zener reference or clamp roles where regulation stability matters.

Availability

1PMT5945A/TR7 is available at Aetrix Electronics and suitable for industrial power supply monitoring, automotive ECU voltage reference, telecom line card protection, and renewable energy inverter applications requiring stable component supply, consistent parametric performance, and long-term manufacturability.

Supply support for 1PMT5945A/TR7 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 (now part of Microchip Technology) is a semiconductor company specializing in high-reliability analog, mixed-signal, and RF solutions for aerospace, defense, industrial, and communications markets.

The Powermite® Zener diode family - including the 1PMT5945A/TR7 - was engineered for high-power-density surface-mount voltage regulation and clamping in thermally demanding environments where traditional axial or DO-204 packages cannot meet thermal or automation requirements.

FAQ

What is the zener voltage tolerance for 1PMT5945A/TR7?

The 1PMT5945A/TR7 has a standard zener voltage tolerance of ±5% at 68 V, measured at IZT = 5.5 mA with TAB temperature maintained at 30°C. Tighter tolerances (±2%, ±1%) are available with suffixes C and D respectively, but the /TR7 variant corresponds to the standard ±5% grade. This tolerance directly impacts regulation accuracy in reference and clamp circuits.

How is thermal performance defined for 1PMT5945A/TR7?

The 1PMT5945A/TR7 has a thermal resistance of 30°C/W from junction to TAB 1. This means that with TAB 1 soldered to an adequately sized PCB thermal pad, the junction temperature rises 30°C for every watt dissipated. At the rated 3.0 W, this yields a 90°C rise above TAB temperature - confirming the need for proper thermal design to stay within the -55°C to +150°C junction limit.

Can 1PMT5945A/TR7 be used in place of through-hole Zeners like 1N5365B?

The 1PMT5945A/TR7 is not a drop-in replacement for 1N5365B due to different package, thermal path, and mounting method. While both are 68 V Zeners, the 1PMT5945A/TR7 uses a surface-mount Powermite® package with TAB 1 as cathode and thermal interface, whereas 1N5365B is DO-201AD through-hole. PCB redesign and thermal validation are required for substitution.

What does the "/TR7" suffix indicate for 1PMT5945A/TR7?

The "/TR7" suffix denotes tape-and-reel packaging per EIA-481 standard, specifically on a 7-inch reel containing 3,000 units. It confirms factory-verified SMT readiness, including proper orientation, tension control, and carrier tape compliance - critical for high-yield automated placement in volume manufacturing of the 1PMT5945A/TR7.

Is 1PMT5945A/TR7 suitable for ESD-sensitive applications?

Yes, the 1PMT5945A/TR7 has an ESD rating exceeding 16 kV per the Human Body Model, verified per ANSI/ESDA STM5.1. This makes it suitable for use in systems requiring robustness against handling and board-level electrostatic discharge - such as field-deployable industrial controllers where the 1PMT5945A/TR7 may be exposed during service or integration.