Microchip Technology 1N4742P/TR8

Overview

1N4742P/TR8 from Microsemi is a 12 V, 5% tolerance, 1 W silicon Zener diode in DO-41 plastic package, rated for 21 mA test current (IZT), 76 Ω dynamic impedance (ZZT), and 0.25 A maximum regulator current (IZM) at 50°C. It provides stable voltage regulation in power supply reference and overvoltage protection circuits across industrial temperature range.

For engineers reviewing the 1N4742P/TR8 datasheet, 1N4742P/TR8 pinout, 1N4742P/TR8 application, or 1N4742P/TR8 equivalent, key selection criteria include Zener voltage tolerance, thermal resistance (45°C/W junction-to-lead), surge current rating (380 mA), reverse leakage (5 µA @ 9.1 V), and RoHS-compliant "e3" variant availability.

Technical Context

This discrete Zener diode operates in reverse breakdown to maintain a stable 12 V reference across a wide current range (0.25 mA to 380 mA). Its 5% voltage tolerance (A-suffix), 76 Ω dynamic impedance at 21 mA, and −65°C to +150°C operating temperature support robust regulation in unregulated DC supplies and feedback networks.

The DO-41 axial-leaded plastic package delivers 45°C/W junction-to-lead thermal resistance at 10 mm lead length and meets IPC/JEDEC J-STD-020B Level 1 moisture sensitivity-no dry pack required. Cathode polarity is marked by a band; operation requires cathode-positive bias relative to anode.

Key Specifications

Pinout & Package

DO-41 (DO-204AL) plastic axial-leaded package with cathode indicated by a single color band. Leads are tin-lead or RoHS-compliant matte-tin plated, solderable per MIL-STD-750 Method 2026. Case is void-free UL94V-0 epoxy.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4742A and MMBZ5242B, the 1N4742P/TR8 uniquely combines 1 W power handling, DO-41 axial-leaded reliability, and EIA-296-compliant tape-and-reel packaging-making it optimal for through-hole power reference designs requiring automated assembly and thermal margin.

Availability

1N4742P/TR8 is available at Aetrix Electronics and suitable for power supply reference, overvoltage protection, and voltage monitoring applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for 1N4742P/TR8 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, RF, and discrete components for aerospace, defense, and industrial markets.

The 1N47xxAP series was designed specifically for general-purpose voltage regulation in cost-sensitive, high-volume industrial and commercial power systems-balancing JEDEC standardization, thermal performance, and manufacturability.

FAQ

What is the Zener voltage tolerance of the 1N4742P/TR8?

The 1N4742P/TR8 has a nominal Zener voltage of 12 V with a ±5% tolerance, as indicated by the "A" suffix in its JEDEC designation. This means the actual measured VZ at 21 mA test current falls between 11.4 V and 12.6 V under standard test conditions (TL = 25°C ±8°C, 90 s after current application). The tolerance is guaranteed per Microsemi's registered JEDEC data and applies across the full operating temperature range.

Does the 1N4742P/TR8 require dry packing before reflow soldering?

No, the 1N4742P/TR8 does not require dry packing. It is classified as Moisture Sensitivity Level 1 per IPC/JEDEC J-STD-020B, meaning it can be stored indefinitely at ≤30°C/60% RH without baking. This eliminates pre-reflow bake cycles and simplifies manufacturing logistics for both manual and automated assembly processes involving the 1N4742P/TR8.

What is the maximum surge current rating for the 1N4742P/TR8?

The 1N4742P/TR8 has a maximum surge current (ISM) rating of 380 mA, measured using a ½-sine wave pulse of 1/120 second duration at 25°C ambient. This rating reflects its ability to safely absorb short-duration overvoltage transients-such as those from inductive switching or ESD events-without degradation, making it suitable for clamping applications in industrial control and power supply circuits containing the 1N4742P/TR8.

How does the thermal resistance of the 1N4742P/TR8 compare between junction-to-lead and junction-to-ambient?

The 1N4742P/TR8 has a junction-to-lead thermal resistance of 45°C/W at 10 mm lead length from the body, but junction-to-ambient rises to 105°C/W when mounted on FR4 with 4 mm² copper pads. This difference highlights the importance of lead length and PCB copper area in thermal design: effective heat sinking via leads enables higher continuous power dissipation than relying solely on board conduction, a critical consideration for sustained operation of the 1N4742P/TR8.

Is the 1N4742P/TR8 RoHS compliant?

Yes, the 1N4742P/TR8 is RoHS compliant. Microsemi offers this part with an "e3" suffix (e.g., 1N4742P/TR8e3) indicating annealed matte-tin terminal plating that meets EU RoHS Directive 2011/65/EU requirements. Standard 1N4742P/TR8 units may use Sn/Pb plating unless otherwise specified; RoHS compliance must be confirmed by ordering the e3-suffixed version, which retains identical electrical and thermal specifications as the base 1N4742P/TR8.