onsemi 1N5254B_T50R

Overview

1N5254B_T50R from ON Semiconductor is a 5% tolerance, 27 V Zener diode in DO-35 glass package, rated for 500 mW power dissipation at 25°C, with 41 Ω dynamic impedance at 10 mA test current and ±0.089 %/°C temperature coefficient - used for precision voltage reference and overvoltage protection in low-power analog circuits.

For engineers reviewing the 1N5254B_T50R datasheet, pinout, applications, or equivalent options, this page delivers verified electrical specs, thermal derating behavior, cathode identification, and direct alternatives for voltage regulation design-in.

Technical Context

The 1N5254B_T50R operates as a silicon planar Zener diode with sharp reverse breakdown at nominal 27 V, designed for stable DC voltage clamping and reference generation in linear power supplies and sensor signal conditioning. Its 500 mW absolute maximum power rating and 4.0 mW/°C thermal derating above 50°C define safe continuous operation limits.

It exhibits 41 Ω dynamic impedance (ZZ) at IZ = 10 mA and 25°C, with leakage current ≤0.25 μA at VR = 21.6 V, and a temperature coefficient of +0.089 %/°C - indicating positive drift with rising junction temperature, requiring thermal layout awareness in precision references.

Key Specifications

Pinout & Package

DO-35 glass axial package: hermetically sealed, 2.0 mm diameter, 4.56 mm body length, 3.05 mm overall length, 1.91 mm lead spacing, cathode identified by color band on glass body.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4748A and BZX55C27, the 1N5254B_T50R offers identical DO-35 form factor and 500 mW rating as BZX55C27 but with slightly higher TC, while differing from 1N4748A in both power capability and mechanical footprint - making it optimal for space-constrained 27 V shunt regulation where thermal drift is managed externally.

Availability

1N5254B_T50R is available at Aetrix Electronics and suitable for industrial sensor interfaces, low-power linear regulators, overvoltage protection circuits, and portable calibration equipment requiring stable component supply and consistent Zener performance.

Supply support for 1N5254B_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

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The 1N52xxB series is part of ON Semiconductor's legacy Zener diode portfolio, engineered for general-purpose voltage regulation and reference applications where cost, reliability, and standardization across voltage grades are critical.

FAQ

What is the nominal Zener voltage of the 1N5254B_T50R?

The 1N5254B_T50R has a nominal Zener voltage of 27 V, with a guaranteed range of 25.65 V to 28.35 V at 10 mA test current and 25°C ambient temperature. This value is specified in the ON Semiconductor 1N5221B–1N5263B datasheet Rev. 3, and reflects the device's role as a precision shunt voltage reference in low-power analog systems. The 1N5254B_T50R maintains this specification under defined thermal and current conditions.

Does the 1N5254B_T50R have a cathode marking, and how is it identified?

Yes, the 1N5254B_T50R uses a color band on the glass body to denote the cathode terminal, consistent with DO-35 package standards. This band is visible as a distinct stripe near one end of the cylindrical glass envelope and must be oriented toward the higher-potential node in reverse-bias operation. The 1N5254B_T50R's cathode marking aligns with JEDEC DO-204AH requirements and is confirmed in ON Semiconductor's package drawings and top-marking documentation.

What is the maximum power dissipation for the 1N5254B_T50R, and how does it change with temperature?

The 1N5254B_T50R has an absolute maximum power dissipation of 500 mW at 25°C ambient, derating linearly by 4.0 mW/°C above 50°C. This means its usable power drops to 400 mW at 75°C and 300 mW at 100°C. These limits are defined in the Absolute Maximum Ratings table of the official 1N5221B–1N5263B datasheet and directly impact thermal design margins in enclosed or high-ambient environments where the 1N5254B_T50R is deployed.

Can the 1N5254B_T50R be used as a replacement for the 1N4748A in existing designs?

No - the 1N5254B_T50R is not a drop-in replacement for the 1N4748A due to differences in package (DO-35 vs. DO-41), power rating (500 mW vs. 1 W), and thermal characteristics. While both regulate at 27 V, the 1N5254B_T50R cannot handle the same load current without exceeding its power limit. Substituting the 1N5254B_T50R for the 1N4748A requires verifying thermal margin, adjusting series current-limiting resistors, and confirming PCB pad compatibility for the smaller DO-35 footprint.

What is the dynamic impedance (Z_Z) of the 1N5254B_T50R, and why does it matter in circuit design?

The 1N5254B_T50R has a dynamic impedance of 41 Ω at I_Z = 10 mA and 25°C, meaning its regulated output voltage varies by ~41 mV per 1 mA change in Zener current. This parameter directly affects regulation accuracy under varying load conditions - for example, a 5 mA load shift causes ~205 mV output deviation. Designers use this value to size series resistors and estimate error budgets in shunt regulator configurations where the 1N5254B_T50R serves as the primary voltage reference.