Diodes Incorporated 1N4728A-T

Overview

1N4728A-T from Diodes Incorporated is a 1.0 W, 3.3 V ±5% Zener diode in DO-41 glass package, with 76 mA test current, 10 Ω maximum Zener impedance at IZT, and -0.08 to -0.05 %/°C temperature coefficient. It provides precision voltage regulation in low-power analog reference and overvoltage protection circuits.

For engineers reviewing the 1N4728A-T datasheet, 1N4728A-T pinout, 1N4728A-T application, or 1N4728A-T equivalent, key selection criteria include nominal Zener voltage tolerance, thermal resistance (175 °C/W), surge current rating (1380 mA for 8.3 ms), and DO-41 mechanical compatibility with through-hole PCB layouts.

Technical Context

This Zener diode operates in reverse breakdown mode to maintain stable 3.3 V across its terminals under controlled current conditions. Its sharp knee characteristic is verified by dual-point Zener impedance measurement (at IZT and IZK) per JEDEC standards.

Designed for DC voltage reference and clamping, it exhibits a negative temperature coefficient (-0.08 to -0.05 %/°C), requiring thermal derating above 50°C (6.67 mW/°C) and strict lead length control (9.5 mm) to sustain full 1.0 W power dissipation.

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

1N4728A-T is available at Aetrix Electronics and suitable for power supply reference, overvoltage clamp, and signal level translation applications requiring stable component supply and legacy through-hole compatibility.

Supply support for 1N4728A-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, headquartered in Plano, Texas, serving industrial, computing, consumer, and communications markets.

The 1N47xxA series belongs to Diodes' standard Zener diode product line, engineered for general-purpose voltage regulation and protection in cost-sensitive, high-volume applications with established DO-41 footprint requirements.

FAQ

What is the maximum allowable junction temperature for 1N4728A-T?

The 1N4728A-T has an operating junction temperature range of -65°C to +175°C. At 25°C ambient, full 1.0 W power dissipation is permitted; above 50°C ambient, power must be linearly derated at 6.67 mW/°C to prevent exceeding the 175°C maximum junction temperature.

How does the -0.08 to -0.05 %/°C temperature coefficient affect circuit performance?

This negative temperature coefficient means the Zener voltage decreases by 0.05–0.08% per °C rise. Over a 100°C range (e.g., -25°C to +75°C), the 3.3 V nominal voltage shifts by approximately -16.5 to -26.4 mV, which must be accounted for in precision reference designs.

Is 1N4728A-T compatible with lead-free reflow soldering processes?

No - the 1N4728A-T uses Sn96.5Ag3.5 finish and is rated for wave and hand soldering per MIL-STD-202 Method 208. Its glass DO-41 package is not rated for peak reflow temperatures (>260°C); use only traditional through-hole soldering methods.

Why is the 8.3 ms surge current rating specified, and what does 1380 mA represent?

The 8.3 ms duration corresponds to one half-cycle of 60 Hz AC line frequency. The 1380 mA rating indicates the peak non-repetitive current the device can safely absorb during such transients without parametric shift or catastrophic failure, validated per industry surge testing standards.