Microchip Technology 1N4746APE3/TR12

Overview

1N4746APE3/TR12 from Microsemi is a 1 W, 18 V ±5% Zener diode in DO-41 plastic package, rated for 14 mA test current, 20 Ω dynamic impedance at I_ZT, and 5 μA reverse leakage at 13.7 V. It provides stable voltage regulation in power supply reference and overvoltage protection circuits across industrial temperature range.

For engineers reviewing the 1N4746APE3/TR12 datasheet, 1N4746APE3/TR12 pinout, 1N4746APE3/TR12 application, or 1N4746APE3/TR12 equivalent, key selection criteria include Zener voltage tolerance, thermal resistance (45 °C/W junction-to-lead), surge current rating (250 mA), RoHS-compliant matte-tin plating, and tape-and-reel packaging per EIA-296.

Technical Context

This axial-lead Zener operates in reverse breakdown to maintain a stable 18 V reference across 0.25–250 mA regulation current. Its 5% voltage tolerance (A suffix), 20 Ω dynamic impedance at 14 mA, and low 0.25 mA knee current (I_ZK) ensure predictable regulation onset and minimal voltage drift under load variation.

Designed for through-hole mounting on FR4 PCBs with 1 oz copper, it delivers 1.0 W steady-state dissipation at T_L < 105 °C (3/8″ lead length) or T_A < 45 °C, with thermal resistance of 105 °C/W junction-to-ambient under defined board layout conditions.

Key Specifications

Pinout & Package

DO-41 (DO-204AL) plastic axial-leaded package with cathode indicated by color band; terminals are anode and cathode only - no internal circuitry or additional pins.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4746A and BZX55C18, the 1N4746APE3/TR12 offers full 1 W power handling with RoHS-compliant plating and EIA-296 tape-and-reel - making it optimal for modern industrial production requiring both robustness and regulatory compliance.

Availability

1N4746APE3/TR12 is available at Aetrix Electronics and suitable for power supply reference, overvoltage protection, and signal level translation requiring stable component supply, consistent RoHS compliance, and automated assembly support.

Supply support for 1N4746APE3/TR12 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 and mixed-signal components for aerospace, defense, and industrial markets.

The 1N47xxAP series was designed for general-purpose, high-stability Zener regulation in harsh-environment power systems - emphasizing wide temperature operation, mechanical ruggedness, and JEDEC-standard compatibility.

FAQ

What is the Zener voltage tolerance of the 1N4746APE3/TR12?

The 1N4746APE3/TR12 has a Zener voltage tolerance of ±5%, indicated by the "A" suffix in its part number. This means its nominal 18 V regulation point falls within 17.1 V to 18.9 V at 14 mA test current and 25 °C lead temperature. The tolerance remains valid across the full −65 °C to +150 °C operating range, though voltage drift with temperature is characterized separately in the datasheet's Figure 3.

Does the 1N4746APE3/TR12 support lead-free soldering processes?

Yes, the 1N4746APE3/TR12 supports lead-free soldering with its RoHS-compliant "e3" suffix, specifying annealed matte-tin plating qualified per MIL-STD-750 Method 2026. It withstands peak solder temperatures of 260 °C for 10 seconds maximum, aligning with standard lead-free reflow profiles. The DO-41 package body is void-free thermosetting epoxy rated UL94V-0.

What is the maximum continuous Zener current for the 1N4746APE3/TR12?

The maximum continuous Zener current for the 1N4746APE3/TR12 is 250 mA at T_L = 25 °C, derived from its 1.0 W power rating and 18 V nominal voltage. At elevated lead temperatures, this current must be reduced per the derating curve in Figure 1. For example, at T_L = 105 °C, the allowable current drops to approximately 9.5 mA to maintain safe junction temperature.

How is polarity marked on the 1N4746APE3/TR12?

The 1N4746APE3/TR12 uses a cathode band - a single colored stripe near one end of the DO-41 cylindrical body - to indicate the cathode terminal. During Zener regulation, the banded (cathode) end must be held at a higher potential than the unbanded (anode) end. This marking is laser-etched or molded into the epoxy body and remains visible after board assembly.

What does the "TR12" suffix mean in 1N4746APE3/TR12?

"TR12" indicates EIA-296 standard tape-and-reel packaging with 12 mm carrier tape width, containing 1,000 units per reel. This format enables automated pick-and-place insertion for through-hole assembly lines. The "TR" denotes tape-and-reel, and "12" specifies the tape width - distinct from the "e3" RoHS suffix and "P" plastic construction identifier also present in the full part number.