Diodes Incorporated 1N4757A-T

Overview

1N4757A-T from Diodes Incorporated is a 1.0W, 51V ±5% Zener diode in DO-41 glass package, designed for precision voltage regulation and overvoltage protection in DC power rails. It delivers 5.0mA test current, 95Ω dynamic impedance at I_ZT, 38.8V minimum knee voltage at 0.25mA, and operates across –65°C to +175°C.

For engineers reviewing the 1N4757A-T datasheet, 1N4757A-T pinout, 1N4757A-T application, or 1N4757A-T equivalent, key selection criteria include Zener voltage tolerance, thermal resistance (175°C/W), surge current rating (90A @ 8.3ms), and DO-41 mechanical compatibility with through-hole PCB layouts.

Technical Context

This discrete Zener diode functions as a two-terminal shunt voltage reference, maintaining stable output voltage by conducting reverse current above its specified breakdown threshold. Its glass DO-41 package ensures hermetic sealing and high-temperature reliability up to +175°C.

The device exhibits a positive temperature coefficient (+0.06% to +0.095%/°C) and is characterized at 25°C with 5.0mA test current, 95Ω Zener impedance at I_ZT, and 5.0µA maximum reverse leakage at 38.8V.

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 ≈ 0.35g.

Key Features

Applications

Availability

1N4757A-T is available at Aetrix Electronics and suitable for power supply regulation, overvoltage protection, voltage reference circuits, and signal level translation requiring stable component supply and DO-41 through-hole compatibility.

Supply support for 1N4757A-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 power management and signal integrity solutions.

The 1N47xxA series belongs to Diodes' legacy Zener diode product line, engineered for cost-effective, high-volume voltage regulation and protection in industrial, telecom, and consumer power systems.

FAQ

What is the maximum continuous power dissipation for 1N4757A-T at 70°C ambient?

At 70°C ambient, the 1N4757A-T must be derated from its 1.0W rating at 25°C. Using the 6.67mW/°C derating factor and 175°C/W thermal resistance, maximum power drops to 0.70W. This ensures junction temperature remains below 175°C with standard 9.5mm lead length.

How does the cathode band identify polarity on the DO-41 package?

The cathode band is a single painted stripe near one end of the DO-41 glass body. When mounted on PCB, the banded end connects to the higher-potential node in reverse-bias operation. Forward voltage drop of 1.2V at 200mA confirms correct orientation during functional testing.

Is 1N4757A-T RoHS compliant and what exemptions apply?

Yes, 1N4757A-T has lead-free finish and is RoHS compliant per EU Directive 2002/95/EC. Glass encapsulation and high-temperature solder exemptions (Annex Notes 5 and 7) apply, permitting use of Sn96.5Ag3.5 terminations compatible with standard reflow profiles.

Can 1N4757A-T replace 1N4756A in existing designs?

No direct replacement is recommended: 1N4756A is rated for 47V ±5%, while 1N4757A is 51V ±5%. Substitution alters regulation point by 4V, potentially exceeding downstream component voltage ratings. Design validation including thermal margin and transient response is required before any interchange.