onsemi 1N751A_T50R

Overview

1N751A_T50R from Fairchild Semiconductor is a 5.1 V, ±5% tolerance silicon Zener diode in DO-35 glass package, rated for 500 mW power dissipation at TL ≤ 75°C, with 17 Ω dynamic impedance at 20 mA and 20 µA reverse leakage at 1 V, used for precision voltage regulation and reference in low-power analog circuits.

For engineers reviewing the 1N751A_T50R datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage tolerance, thermal derating behavior, cathode band identification, and DO-35 mechanical compatibility in space-constrained PCB layouts.

Technical Context

This device operates as a two-terminal voltage reference diode relying on controlled reverse-biased avalanche breakdown. Its 5.1 V nominal zener voltage is specified at 20 mA test current, with dynamic impedance of 17 Ω confirming stable regulation under small-signal load variations.

The DO-35 glass package enables operation across -65°C to +200°C, with power derating at 4.0 mW/°C above 75°C ambient lead temperature. Reverse leakage remains ≤1 µA at VR = 1 V and ≤20 µA at VR = 1 V per absolute maximum ratings table.

Key Specifications

Pinout & Package

DO-35 glass axial package with cathode identified by a single black band near one end. No active pin numbering-cathode and anode are unidirectional terminals defined solely by polarity marking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N751A_T50R, 1N4733A offers higher power handling in a larger package, while BZX55-C5V1 matches form factor but trades off regulation precision and leakage performance for broader manufacturing availability.

Availability

1N751A_T50R is available at Aetrix Electronics and suitable for overvoltage protection, analog reference generation, and power supply feedback applications requiring stable component supply, consistent DO-35 mechanical fit, and traceable lot-controlled sourcing.

Supply support for 1N751A_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 semiconductor company specializing in power management, signal conditioning, and discrete components before its acquisition by ON Semiconductor in 2016.

The 1N7xxA series was designed for general-purpose voltage regulation and clamping in cost-sensitive, space-constrained consumer and industrial electronics where DO-35 compatibility and ±5% tolerance were primary requirements.

FAQ

What is the exact zener voltage range for 1N751A_T50R at 20 mA test current?

The 1N751A_T50R has a guaranteed zener voltage range of 4.85 V (minimum) to 5.36 V (maximum) when measured at IZ = 20 mA and TA = 25°C. This 5.1 V nominal rating with ±5% tolerance is confirmed in the "Electrical Characteristics" table of the Fairchild Rev. D1 datasheet and applies directly to the 1N751A_T50R variant.

Does 1N751A_T50R have a cathode band, and how is it oriented?

Yes, the 1N751A_T50R uses a DO-35 glass package with a single black cathode band located near one end of the body. The banded end is the cathode terminal, and the unbanded end is the anode. This marking follows Fairchild's standard top-marking convention for 1Nxx series devices and is visible under magnification on production units.

What is the maximum power dissipation and thermal derating behavior of 1N751A_T50R?

The 1N751A_T50R is rated for 500 mW power dissipation at lead temperature TL ≤ 75°C. Above 75°C, it derates linearly at 4.0 mW/°C. This derating curve is defined in the Absolute Maximum Ratings table and must be applied when calculating safe operating area in environments exceeding 75°C ambient or with elevated PCB copper thermal resistance.

Can 1N751A_T50R be used in surface-mount designs?

No, the 1N751A_T50R is exclusively available in the through-hole DO-35 axial glass package and is not offered in SMD variants such as SOD-123 or DO-213AA. For surface-mount equivalents, engineers should evaluate alternatives like MMBZ5231B or BZX84-C5V1, which differ in package, impedance, and leakage characteristics compared to the 1N751A_T50R.

What is the reverse leakage current specification for 1N751A_T50R at 1 V reverse voltage?

The reverse leakage current (IR) for 1N751A_T50R is specified as ≤1 µA at VR = 1 V and TA = 25°C. This value is listed in the "Electrical Characteristics" table under the 1N751A row and reflects the device's ability to minimize parasitic loading in high-impedance bias networks or precision reference circuits.