Diodes Incorporated 1N4742A-T

Overview

1N4742A-T from Diodes Incorporated is a 12 V, 1.0 W axial-leaded Zener diode in DO-41 glass package, rated for ±5% voltage tolerance at 21 mA test current, with 9.0 Ω dynamic impedance and temperature coefficient of +0.045 to +0.085 %/°C; used for precision voltage regulation in power supply reference circuits.

For engineers reviewing the 1N4742A-T datasheet, 1N4742A-T pinout, 1N4742A-T application, or 1N4742A-T equivalent, this part serves as a stable, low-cost shunt regulator in DC-DC feedback loops, overvoltage clamping networks, and analog reference generation where ±5% accuracy and 12 V nominal breakdown are required.

Technical Context

This Zener diode operates in reverse breakdown mode with a sharp knee at IZT = 21 mA, delivering stable 12 V regulation under steady-state DC conditions. Its DO-41 glass package provides hermetic sealing and UL 94V-0 flammability rating, supporting reliable operation from –65 °C to +175 °C.

Thermal resistance is 175 °C/W (junction-to-ambient) at TA = 25 °C with 9.5 mm lead length; power derating begins above 50 °C at 6.67 mW/°C. Reverse leakage remains ≤5.0 µA at VR = 9.1 V, ensuring low standby current in clamp configurations.

Key Specifications

Pinout & Package

DO-41 glass axial package with cathode band marking; two-terminal device with no internal pin numbering-cathode identified by painted band, anode by unmarked end.

Key Features

Applications

Availability

1N4742A-T is available at Aetrix Electronics and suitable for switch-mode power supplies, microcontroller reset circuits, industrial sensor conditioning, and LED driver protection requiring stable component supply and full traceability.

Supply support for 1N4742A-T 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability, industry-standard components for power management and signal integrity.

The 1N47xxA series belongs to Diodes' legacy Zener diode product line, designed specifically for general-purpose voltage regulation and clamping in cost-sensitive, high-volume industrial and consumer applications.

FAQ

What is the maximum continuous Zener current for 1N4742A-T at 25°C?

The maximum continuous Zener current is derived from P_D/V_Z = 1.0 W / 12 V ≈ 83 mA. However, the rated test current is 21 mA, and operation above this level requires thermal derating per the 6.67 mW/°C curve above 50°C ambient. Sustained operation near 83 mA is not recommended without heatsinking or airflow.

Is 1N4742A-T compatible with lead-free reflow soldering processes?

Yes - the device features Sn96.5Ag3.5 terminations and is rated for solderability per MIL-STD-202, Method 208. It supports standard lead-free reflow profiles (peak ~260°C), but its glass DO-41 package requires careful thermal profiling to avoid mechanical stress cracking during rapid heating or cooling.

How does the temperature coefficient affect regulation accuracy over temperature?

With a TC of +0.045 to +0.085 %/°C, the Zener voltage increases by 5.4–10.2 mV/°C. Over a 100°C range (–25°C to +75°C), this yields a total shift of +0.54 V to +1.02 V - meaning regulation shifts from ~11.46 V to ~12.54 V. Designs requiring tighter stability must include TC compensation or select tighter-tolerance parts.

Can 1N4742A-T replace 1N4742A-A in the same PCB footprint?

Yes - both share identical DO-41 glass packaging, electrical specifications, and cathode band marking. The only difference is packaging format: "-T" denotes tape-and-reel (5,000 pcs), while "-A" denotes ammo pack. No layout or soldering process changes are needed for substitution.