Microchip Technology 1PMT5946/TR7

Overview

1PMT5946B from Microsemi is a 75 V, 3.0 W surface-mount Zener diode in the Powermite® package, featuring a full metallic bottom, integral heat sink locking tab, and 16 kV HBM ESD rating. It delivers stable voltage regulation in space-constrained power supply rails and overvoltage protection circuits with low reverse leakage (≤2000 µA at 1 V) and dynamic impedance of 140 Ω at 5.0 mA test current.

For engineers reviewing the 1PMT5946B datasheet, 1PMT5946B pinout, 1PMT5946B application, or 1PMT5946B equivalent, key selection criteria include its 75 V nominal Zener voltage, 3.0 W DC power dissipation at TAB 1 = 60°C, thermal resistance of 30°C/W junction-to-tab, ±5% voltage tolerance (C/D suffixes for tighter grades), and DO-216 mechanical outline compatibility.

Technical Context

This Zener diode operates as a precision shunt voltage reference and overvoltage clamp in DC power conditioning stages. Its Powermite® package enables direct thermal coupling to PCB copper via TAB 1 (cathode), supporting reliable 3.0 W dissipation when mounted on ≥1 sq-in copper area.

The device exhibits a sharp knee at IZK = 0.25 mA with ZZK = 2000 Ω, enabling low-current regulation stability. Reverse leakage remains ≤1 µA up to VR = 1 V, and forward voltage is 1.2 V at 200 mA - confirming robust conduction capability during fault conditions.

Key Specifications

Pinout & Package

Package: Powermite® (DO-216AA), molded surface-mount package with full metallic bottom and cathode designated by TAB 1. Mounting orientation is unrestricted.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMCJ75A and BZX84-C75, the 1PMT5946B uniquely combines 3.0 W DC power handling, low-impedance regulation (140 Ω), and direct PCB thermal coupling - making it the sole choice for high-reliability, high-power Zener regulation in industrial and automotive environments.

Availability

1PMT5946B is available at Aetrix Electronics and suitable for industrial power supplies, automotive body control modules, telecom line card protection, and medical imaging bias circuits requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 1PMT5946B 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 series was engineered for high-power surface-mount voltage regulation in thermally demanding environments, targeting applications where traditional through-hole Zeners or low-power SMD devices fail to meet thermal or reliability requirements.

FAQ

What is the cathode identification method for 1PMT5946B?

The cathode of the 1PMT5946B is designated by TAB 1, which is the full metallic bottom surface of the Powermite® package. This tab serves both as the electrical cathode terminal and the primary thermal path to the PCB. During layout, TAB 1 must be connected to the cathode net and exposed copper for thermal management - no separate cathode marking is present on the molded body.

Can 1PMT5946B be used in place of a through-hole 1N5359B?

Yes, the 1PMT5946B provides equivalent 75 V Zener functionality to the 1N5359B but in a surface-mount Powermite® package. While both share identical VZ (75 V), IZT (5 mA), and power rating (3.0 W), the 1PMT5946B offers superior thermal performance via its metallic tab and eliminates flux entrapment risks - making it ideal for automated assembly and high-density layouts where the 1N5359B's axial lead form factor is impractical.

What is the maximum continuous current 1PMT5946B can handle at 75 V?

The 1PMT5946B supports a maximum Zener current (IZM) of 33.0 mA at 75 V, calculated from its 3.0 W power rating (P = V × I → I = 3.0 W / 75 V). This assumes TAB 1 temperature is maintained at ≤60°C via adequate PCB copper area. At higher ambient or junction temperatures, derating is required per the thermal resistance specification of 30°C/W.

Does 1PMT5946B require a heatsink beyond the PCB copper pad?

No external heatsink is required for the 1PMT5946B when mounted on a minimum 1 square inch of 2 oz copper connected directly to TAB 1. The Powermite® package's full metallic bottom and integral locking tab provide sufficient thermal conduction to the PCB. Adding an external heatsink offers negligible improvement unless board-level thermal resistance exceeds 30°C/W - a condition typically avoided by proper pad design and airflow.

Is 1PMT5946B compliant with RoHS and REACH regulations?

Yes, the 1PMT5946B is RoHS-compliant and REACH-conformant, as confirmed by Microsemi's product change notifications and material declarations dated prior to the 2019 Microchip acquisition. It contains no lead, mercury, cadmium, hexavalent chromium, PBBs, or PBDEs above threshold limits, and all substances of very high concern (SVHC) are below 0.1% weight by weight per homogeneous material.