Diodes Incorporated 1N4729A-T

Overview

1N4729A-T from Diodes Incorporated is a 1.0 W, 3.6 V ±5% Zener diode in DO-41 glass package, designed for voltage regulation and reference applications with 69 mA test current, 10 Ω dynamic impedance at I_ZT, and -0.08 to -0.05 %/°C temperature coefficient. It operates across -65°C to +175°C and is RoHS-compliant with Sn96.5Ag3.5 terminations.

For engineers reviewing the 1N4729A-T datasheet, 1N4729A-T pinout, 1N4729A-T application, or 1N4729A-T equivalent, this part serves as a stable, low-power voltage reference in linear power supplies, overvoltage protection circuits, and analog signal conditioning where precise 3.6 V clamping is required under DC or low-frequency conditions.

Technical Context

This Zener diode operates in reverse breakdown mode with a nominal Zener voltage of 3.6 V at 69 mA (I_ZT). Its 10 Ω Zener impedance at I_ZT ensures tight regulation under small-signal variations, while its negative temperature coefficient (-0.08 to -0.05 %/°C) enables predictable drift behavior in ambient-temperature-varying environments.

The device is rated for 1.0 W power dissipation at 25°C, derating linearly at 6.67 mW/°C above 50°C when leads are held at 50°C with 9.5 mm length from case. Its DO-41 glass package provides UL 94V-0 flammability rating and supports reliable soldering per MIL-STD-202, Method 208.

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 is unmarked end. Leads are Sn96.5Ag3.5 plated and solderable per MIL-STD-202, Method 208.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DFLZ3.6, the 1N4729A-T offers 100% higher power capacity and 33% lower Z_ZT, making it preferable in legacy through-hole designs requiring robust shunt regulation; versus 1N4729A-A, it delivers identical electrical behavior with optimized reel-based manufacturability.

Availability

1N4729A-T is available at Aetrix Electronics and suitable for linear power supply reference, overvoltage clamp circuit, and analog signal level shifting applications requiring stable component supply and long-term obsolescence resilience.

Supply support for 1N4729A-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, cost-optimized components for industrial, computing, and consumer markets.

The 1N47xxA series belongs to Diodes' standard Zener diode product line, engineered for general-purpose voltage regulation and reference duties in cost-sensitive, high-volume applications where proven DO-41 reliability and wide V_Z coverage (3.3–75 V) are essential.

FAQ

What is the maximum continuous Zener current for 1N4729A-T at 25°C?

The maximum continuous Zener current is derived from P_d/V_Z = 1000 mW / 3.6 V ≈ 278 mA. However, the device is characterized at 69 mA (I_ZT) for specification compliance, and sustained operation above 69 mA requires thermal derating per the 6.67 mW/°C curve above 50°C ambient.

Is 1N4729A-T suitable for use in automotive under-hood environments?

Yes-it is rated for junction temperatures from -65°C to +175°C and qualified for industrial-grade reliability. Its DO-41 glass package withstands thermal cycling and vibration; however, system-level validation of thermal management and transient immunity remains necessary per vehicle-specific requirements.

How does the temperature coefficient affect regulation accuracy over temperature?

With a coefficient of -0.08 to -0.05 %/°C, V_Z decreases by approximately 1.8–2.3 mV/°C near 25°C. Over a 100°C rise (e.g., 25°C to 125°C), V_Z shifts down by 0.18–0.23 V, resulting in ~5–6% total deviation-acceptable for non-precision references but insufficient for metrology-grade applications.

Can 1N4729A-T replace 1N4728A in an existing design?

Only if the 3.3 V → 3.6 V shift is acceptable in the target circuit. Both share identical package, power rating, and Z_ZT, but the 0.3 V higher V_Z alters regulation point, feedback divider ratios, and clamping thresholds-requiring verification of loop stability and worst-case voltage margins before substitution.