Microchip Technology 1PMT5945E3/TR13

Overview

1PMT5945E3/TR13 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 thermal resistance of 30°C/W junction-to-TAB1 - used for precision voltage regulation and overvoltage protection in compact DC power supplies.

For engineers reviewing the 1PMT5945E3/TR13 datasheet, 1PMT5945E3/TR13 pinout, 1PMT5945E3/TR13 application, or 1PMT5945E3/TR13 equivalent, key selection criteria include Zener voltage tolerance, power derating above 60°C, reverse leakage at 51.2 V, knee current behavior at 0.25 mA, and compatibility with EIA-481 tape-and-reel automated assembly.

Technical Context

This Zener diode operates as a two-terminal voltage reference device with cathode designated by TAB 1, requiring no external biasing circuitry. Its full metallic bottom and integral heat sink locking tab enable direct thermal conduction to PCB copper, supporting stable regulation under transient load conditions.

The device exhibits low reverse leakage (≤1 µA at VR = 51.2 V), tight voltage regulation (VZ = 68 V ±5% at IZT = 5.5 mA), and defined knee characteristics (IZK = 0.25 mA, ZZK = 1700 Ω), making it suitable for low-current reference and clamping applications where stability across -55°C to +150°C junction temperature is required.

Key Specifications

Pinout & Package

Package: Powermite® surface-mount molded package with full metallic bottom and integral heat sink locking tab; cathode identified by TAB 1; DO-216 outline; weight ≈ 0.016 g.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N5365B and BZX84-C68, the 1PMT5945E3/TR13 uniquely combines 3 W power handling, SMT manufacturability, and 30°C/W thermal resistance in the Powermite® package - enabling compact, thermally robust designs where both power density and assembly scalability matter.

Availability

1PMT5945E3/TR13 is available at Aetrix Electronics and suitable for DC power supply regulation, overvoltage protection clamping, and low-power sensor reference applications requiring stable component supply and EIA-481 tape-and-reel compatibility.

Supply support for 1PMT5945E3/TR13 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 U.S.-based semiconductor company specializing in high-reliability analog, mixed-signal, and radiation-hardened components for aerospace, defense, and industrial markets.

The Powermite® Zener diode product line was designed to deliver high-power surface-mount voltage regulation in space-constrained, thermally demanding applications - bridging the performance gap between leaded and modern SMT solutions.

FAQ

What is the Zener voltage tolerance for 1PMT5945E3/TR13?

The 1PMT5945E3/TR13 has a standard Zener voltage tolerance of ±5% at 68 V, measured at 5.5 mA test current and TAB 1 temperature of 30°C. Tighter tolerances (±2%, ±1%) are available with suffixes C and D, but the E3/TR13 variant specifies ±5%. This tolerance directly impacts regulation accuracy in feedback circuits using the 1PMT5945E3/TR13 as a reference.

How is thermal management handled for 1PMT5945E3/TR13 in PCB layout?

The 1PMT5945E3/TR13 relies on TAB 1 as its primary thermal path, with a specified junction-to-TAB thermal resistance of 30°C/W. Effective thermal management requires connecting TAB 1 to a large copper pour or internal ground plane. The full metallic bottom and locking tab enhance conduction, and the 3.0 W rating assumes TAB 1 is maintained at ≤60°C - so PCB copper area must be sized accordingly for the 1PMT5945E3/TR13's expected power dissipation.

What does the "TR13" suffix indicate in 1PMT5945E3/TR13?

The "TR13" suffix in 1PMT5945E3/TR13 denotes packaging in a 13-inch tape-and-reel format containing 12,000 units, compliant with EIA Standard 481. This format is optimized for high-volume automated SMT placement. The "E3" portion indicates the ±5% Zener voltage tolerance grade. Together, TR13 confirms full manufacturability readiness for production lines using standard pick-and-place equipment handling 13-inch reels.

Can 1PMT5945E3/TR13 be used in place of through-hole Zeners like 1N5365B?

The 1PMT5945E3/TR13 provides the same 68 V Zener voltage as the 1N5365B but in a surface-mount Powermite® package with different thermal and mechanical characteristics. While functionally similar, it is not a drop-in replacement due to differing package outline (DO-216 vs. DO-15), mounting method, and thermal path. Redesign of the PCB footprint and thermal pad is required to use the 1PMT5945E3/TR13 instead of the 1N5365B.

What is the maximum reverse voltage (VR) that guarantees IR ≤1 µA for 1PMT5945E3/TR13?

Per the datasheet, the 1PMT5945E3/TR13 guarantees reverse leakage current (IR) ≤1 µA at a reverse voltage (VR) of 51.2 V. This value corresponds to 75% of the nominal Zener voltage (68 V × 0.75 = 51 V), and is specified under test conditions of TL = 30°C. Operating above 51.2 V increases leakage exponentially, so 1PMT5945E3/TR13 should be biased below this threshold in high-impedance sensing applications.