onsemi 1N755A_T50R

Overview

1N755A_T50R from Fairchild Semiconductor is a 7.5 V ±5% silicon Zener diode in DO-35 glass package, rated for 500 mW power dissipation at TL ≤ 75°C, with 6 Ω dynamic impedance at 20 mA test current and 0.1 µA reverse leakage at 1 V, used for precision voltage regulation in low-power analog reference and overvoltage protection circuits.

For engineers reviewing the 1N755A_T50R datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage tolerance (±5%), thermal derating slope (4.0 mW/°C above 75°C), cathode-band polarity marking, and DO-35 mechanical compatibility with legacy through-hole PCB layouts.

Technical Context

The 1N755A_T50R operates as a two-terminal voltage reference device relying on controlled avalanche breakdown in its p-n junction. Its zener voltage is specified at 20 mA test current with tight 5% tolerance and validated across -65°C to +200°C operating range.

It exhibits 6 Ω dynamic impedance at IZ = 20 mA and maintains 0.1 µA maximum reverse leakage at VR = 1 V, supporting stable regulation in low-current bias networks. Power handling follows a linear derating curve of 4.0 mW/°C above 75°C ambient lead temperature.

Key Specifications

Pinout & Package

DO-35 glass axial package with cathode indicated by a single color band on the body. Two terminals only: anode and cathode - no internal connections or multi-pin configuration.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N755A_T50R, the 1N4734A offers higher power capacity in a larger DO-41 package, while the BZX55C7V5 matches the DO-35 form factor but trades lower leakage for higher dynamic impedance-making 1N755A_T50R optimal for balanced regulation accuracy, size, and thermal response in space-constrained analog systems.

Availability

1N755A_T50R is available at Aetrix Electronics and suitable for power supply reference, overvoltage clamp, and temperature-stable bias network applications requiring stable component supply and long-lifecycle support.

Supply support for 1N755A_T50R 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

Fairchild Semiconductor was a U.S.-based designer and manufacturer of high-performance analog and power semiconductors, acquired by ON Semiconductor in 2016; known for reliability-critical discrete components.

The 1N755A_T50R belongs to Fairchild's legacy 1N7xxA Zener series, engineered for general-purpose voltage regulation and clamping in industrial, automotive, and consumer electronics where DO-35 compatibility and ±5% tolerance are design requirements.

FAQ

What is the exact zener voltage range for 1N755A_T50R at 20 mA?

The 1N755A_T50R has a guaranteed zener voltage range of 7.13 V to 7.88 V at IZ = 20 mA, corresponding to its ±5% tolerance specification around the nominal 7.5 V rating. This range is validated per Fairchild Rev. D1 datasheet and applies under TA = 25°C with 3/8" lead length and thermal equilibrium at TL = 30°C ± 1°C. The 1N755A_T50R must be operated within this window to meet its published regulation performance.

Does 1N755A_T50R have a cathode marking, and how is it identified?

Yes, the 1N755A_T50R uses a single color band on the DO-35 glass body to denote the cathode terminal, consistent with JEDEC-standard axial diode marking. This band aligns with Line 3 "A" in its top-marking scheme (F / 55 / A) and must be oriented toward the higher-potential node in shunt regulator or clamp configurations. The 1N755A_T50R's cathode identification is mechanically unambiguous and critical for correct PCB placement.

What is the maximum reverse leakage current for 1N755A_T50R, and at what voltage is it measured?

The 1N755A_T50R specifies a maximum reverse leakage current (IR) of 0.1 µA, measured at VR = 1 V and TA = 25°C. This value reflects the diode's low-leakage capability in sub-breakdown conditions and supports high-impedance reference applications. The 1N755A_T50R maintains this leakage performance across its full -65°C to +200°C storage and operating range, as confirmed in Fairchild's Absolute Maximum Ratings table.

Can 1N755A_T50R be used in surface-mount designs?

No, the 1N755A_T50R is packaged exclusively in the DO-35 axial glass case, which is a through-hole format requiring radial lead insertion and soldering. It has no SMD variant or compatible surface-mount equivalent in the 1N7xxA family. Designers requiring SMT implementation must select alternatives such as the BZX55C7V5 (DO-35) or BZX84-C7V5 (SOT-23), but those are not drop-in replacements for the 1N755A_T50R due to differing package geometry and thermal behavior.

How does thermal derating apply to 1N755A_T50R in real-world PCB layouts?

The 1N755A_T50R derates linearly at 4.0 mW/°C above TL = 75°C, meaning its usable power drops to 400 mW at TL = 100°C and 300 mW at TL = 125°C. Since TL is measured at the lead 3/8" from the package body, actual board-level thermal performance depends on copper pour area, adjacent heat sources, and airflow. For reliable operation, the 1N755A_T50R should be placed away from high-power components and verified with thermal imaging or thermocouple measurement at the lead root.