Diodes Incorporated 1N4740A-T

Overview

1N4740A-T from Diodes Incorporated is a 1.0W, 10V ±5% Zener diode in DO-41 glass package, with 7.0Ω maximum zener impedance at 25mA test current, 0.25mA minimum knee current, and temperature coefficient of +0.04 to +0.08%/°C. It provides stable voltage reference in low-power linear regulators and overvoltage protection circuits for industrial sensor interfaces.

For engineers reviewing the 1N4740A-T datasheet, 1N4740A-T pinout, 1N4740A-T application, or 1N4740A-T equivalent, key selection criteria include nominal zener voltage tolerance, thermal resistance (175°C/W), surge current rating (454mA @ 8.3ms), and DO-41 mechanical compatibility with through-hole PCB layouts.

Technical Context

This device operates as a two-terminal voltage reference, relying on controlled reverse-biased avalanche breakdown. Its 10V nominal zener voltage is specified at 25mA (IZT), with a sharp knee established by measuring zener impedance at both IZT and IZK (0.25mA).

The DO-41 glass package enables operation from –65°C to +175°C, and its 175°C/W junction-to-ambient thermal resistance requires lead length control (9.5mm from case) to maintain full 1.0W power dissipation above 50°C ambient.

Key Specifications

Pinout & Package

DO-41 glass axial package with cathode band marking; leads are Sn96.5Ag3.5 solderable per MIL-STD-202, Method 208; weight ≈ 0.35 g.

Key Features

Applications

Availability

1N4740A-T is available at Aetrix Electronics and suitable for industrial sensor interfaces, microcontroller reset circuits, DC-DC converter feedback networks, and overvoltage protection clamps requiring stable component supply and long-term obsolescence management.

Supply support for 1N4740A-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 components for industrial, computing, and consumer markets.

The 1N47xxA series belongs to Diodes' legacy Zener diode product line, designed specifically for general-purpose voltage regulation and clamping in cost-sensitive, through-hole assembled systems.

FAQ

What is the maximum continuous power dissipation for 1N4740A-T at 70°C ambient?

At 70°C ambient, the 1N4740A-T must be derated from its 1.0W rating at 25°C. With a thermal resistance of 175°C/W and 45°C temperature rise allowance, maximum power is 1.0W × (1 − (70−50)/6.67) = 0.70W, assuming leads held at 50°C per datasheet note.

How does the +0.04 to +0.08%/°C temperature coefficient affect voltage stability?

Over a 50°C temperature range (e.g., 25°C to 75°C), the 10V nominal zener voltage shifts by +20mV to +40mV. This drift is predictable and acceptable in non-precision applications like reset thresholds or coarse supply monitoring where ±0.5% total error is tolerable.

Can 1N4740A-T replace 1N4740A-A in existing designs?

Yes - both share identical electrical specifications and DO-41 packaging. The "-T" suffix denotes tape-and-reel packaging (5,000 units/reel), while "-A" indicates ammo pack. No circuit-level differences exist; only handling and assembly logistics differ.

Is 1N4740A-T RoHS compliant?

Yes - the device features Sn96.5Ag3.5 lead finish and complies with EU Directive 2002/95/EC (RoHS), with exemptions applied for glass encapsulation and high-temperature solder per Annex Notes 5 and 7.