Diodes Incorporated 1N5248B-T

Overview

1N5248B-T from Diodes Incorporated is an obsolete 18 V, ±5% tolerance, 500 mW surface-mount Zener diode in a hermetic DO-35 glass package, rated for operation from –65°C to +175°C, with 21 Ω dynamic impedance at 7.0 mA test current and +0.085 %/°C temperature coefficient-used for precision voltage reference and overvoltage protection in low-power analog circuits.

For engineers reviewing the 1N5248B-T datasheet, 1N5248B-T pinout, 1N5248B-T application, or 1N5248B-T equivalent, key selection factors include its 18 V nominal Zener voltage, tight ±5% tolerance, low 21 Ω Zener impedance at I_ZT, hermetic glass packaging, and RoHS-compliant Sn96.5Ag3.5 terminations-critical for stable biasing in instrumentation and power supply feedback loops.

Technical Context

This discrete Zener diode operates in reverse breakdown to maintain a stable 18 V reference across load variations, with thermal resistance of 300 °C/W enabling reliable dissipation up to 500 mW when leads are held ≤75°C. Its DO-35 glass package ensures hermeticity and long-term parameter stability under thermal cycling.

The device exhibits a positive temperature coefficient of +0.085 %/°C, indicating increasing Zener voltage with rising junction temperature-important for temperature-compensated reference designs where drift must be modeled or offset. Reverse leakage remains ≤0.1 µA at 14 V, supporting low-current sensing applications.

Key Specifications

Pinout & Package

Package: DO-35 glass axial package with cathode band marking; hermetic, lead-free Sn96.5Ag3.5 terminations; weight ≈0.13 g; moisture sensitivity Level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N5248B-T, MMSZ5248B offers compact SMT integration but sacrifices 300 mW power headroom and adds 9 Ω impedance; 1N4746A provides greater thermal robustness and lower impedance in a larger through-hole format-making it preferable for higher-reliability or higher-power analog references.

Availability

1N5248B-T is available at Aetrix Electronics and suitable for industrial sensor conditioning, low-power voltage reference, overvoltage protection clamp, and power supply feedback divider applications requiring stable component supply despite its obsolete status.

Supply support for 1N5248B-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, with design and manufacturing operations across Asia and the Americas.

The 1N52xxB series belongs to Diodes' legacy Zener diode product line, engineered for precision voltage regulation and clamping in cost-sensitive, high-reliability analog systems-especially where hermetic stability and wide temperature operation are essential.

FAQ

Is 1N5248B-T still in production?

No, 1N5248B-T is officially obsolete and discontinued by Diodes Incorporated as of September 2019. It is no longer manufactured, but Aetrix Electronics maintains limited legacy inventory and supports last-time buys for qualified industrial and aerospace programs with documented continuity plans.

What is the correct polarity marking for 1N5248B-T?

The cathode is marked by a distinct color band on the glass body of the DO-35 package. When installed, the banded end connects to the higher-potential node in reverse-bias configuration-i.e., the cathode is the regulated output terminal delivering +18 V relative to the anode.

Can 1N5248B-T replace 1N4746A in a circuit?

Only if power dissipation stays below 500 mW and thermal management ensures lead temperature remains ≤75°C. While both have 18 V Zener voltage, 1N4746A handles 1 W and uses DO-41 packaging-offering greater thermal margin and mechanical robustness in high-vibration environments.

Why does 1N5248B-T have a positive temperature coefficient?

Its +0.085 %/°C coefficient arises from the dominant avalanche breakdown mechanism at 18 V, where increased thermal energy enhances carrier multiplication. This behavior is intrinsic to the silicon doping profile and junction design-not a defect-and must be accounted for in temperature-critical reference designs.