Microchip Technology 1PMT5939/TR13

Overview

1PMT5939B from Microsemi is a 39 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 45 Ω dynamic impedance at 9.6 mA test current and 900 µA max reverse leakage at 29.7 V. It serves as a precision voltage reference or overvoltage clamp in power supply regulation circuits.

For engineers reviewing the 1PMT5939B datasheet, 1PMT5939B pinout, 1PMT5939B application, or 1PMT5939B equivalent, key selection criteria include its 39 V nominal Zener voltage, 3.0 W thermal capability via metallic tab, DO-216 mechanical outline, ESD rating >16 kV HBM, and compatibility with automated SMT assembly.

Technical Context

This Zener diode operates in reverse breakdown to maintain stable voltage across load variations and temperature shifts. Its Powermite® package integrates a full metallic bottom (TAB 1) for flux-free soldering and a locking tab that functions as both mechanical anchor and thermal path to PCB copper.

Electrical behavior is defined at TL = 30°C with IZT = 9.6 mA; Zener voltage drift is characterized per Micro Note 202, and knee impedance (ZZK = 0.25 Ω) confirms low-current regulation capability down to IZK = 0.25 mA.

Key Specifications

Pinout & Package

The 1PMT5939B uses a DO-216 molded surface-mount package with cathode designated by TAB 1. The full metallic bottom serves as both electrical cathode terminal and primary thermal interface.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N5359B and 1N5255B, the 1PMT5939B delivers 2× higher power rating in half the footprint, direct thermal coupling via TAB 1, and ESD robustness exceeding 16 kV-making it uniquely suited for space-constrained, high-reliability SMT power management.

Availability

1PMT5939B is available at Aetrix Electronics and suitable for switch-mode power supplies, industrial sensor interfaces, automotive body control modules, and programmable logic controller input protection requiring stable component supply across extended production lifecycles.

Supply support for 1PMT5939B 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 specifically for surface-mount power regulation and transient suppression where thermal performance, automated assembly compatibility, and high-voltage stability are critical.

FAQ

What is the maximum power dissipation rating for the 1PMT5939B?

The 1PMT5939B is rated for 3.0 W DC power dissipation when TAB 1 is maintained at 60°C. This rating assumes proper thermal coupling to a PCB copper pour; derating is required above 60°C ambient or with reduced copper area. The 30°C/W junction-to-TAB thermal resistance enables predictable thermal design in compact layouts.

How is cathode polarity identified on the 1PMT5939B package?

The cathode of the 1PMT5939B is designated by TAB 1, which is the full metallic bottom surface of the DO-216 package. This tab serves as both the cathode electrical terminal and the primary thermal conduction path. Polarity is confirmed mechanically-not by marking-so correct orientation during placement is essential for functional and thermal performance.

Does the 1PMT5939B meet industry-standard ESD requirements?

Yes, the 1PMT5939B has an ESD rating exceeding 16 kV per the Human Body Model (HBM), verified per ANSI/ESDA/JEDEC JS-001. This level of robustness supports safe handling in automated SMT lines and ensures reliability in end equipment exposed to routine electrostatic discharge events without additional protection circuitry.

Can the 1PMT5939B be used in place of through-hole Zener diodes like the 1N5255B?

No-direct substitution is not recommended. While both provide ~39 V Zener voltage, the 1PMT5939B is a 3.0 W surface-mount device with DO-216 footprint and thermal tab, whereas the 1N5255B is a 0.5 W through-hole DO-35 part. Differences in power rating, package, thermal path, and mounting method require PCB redesign and thermal validation before replacement.

What tolerance options are available for the 1PMT5939B Zener voltage?

The standard 1PMT5939B offers ±5% Zener voltage tolerance. Tighter tolerances are available with suffix codes: ±2% with suffix C (e.g., 1PMT5939C) and ±1% with suffix D (e.g., 1PMT5939D). These variants share identical thermal, mechanical, and reliability specifications-only the VZ distribution band differs.