Diodes Incorporated 1N5222B-T

Overview

1N5222B-T from Diodes Incorporated is a 2.5 V, ±5% tolerance, 500 mW hermetic glass-encapsulated Zener diode in DO-35 package, designed for precision voltage regulation and reference in low-power analog circuits, power supply feedback loops, and overvoltage protection stages.

For engineers reviewing the 1N5222B-T datasheet, 1N5222B-T pinout, 1N5222B-T application, or 1N5222B-T equivalent, key selection criteria include zener voltage accuracy at 20 mA test current, 30 Ω dynamic impedance at I_ZT, -0.085 %/°C temperature coefficient, and DO-35 mechanical compatibility with through-hole reflow or hand-soldering processes.

Technical Context

This discrete Zener diode operates in reverse breakdown to maintain stable voltage across its terminals under varying load and temperature conditions. Its 2.5 V nominal zener voltage is specified at I_ZT = 20 mA with ±5% tolerance and exhibits a negative temperature coefficient of -0.085 %/°C, indicating decreasing V_Z with rising junction temperature.

The device features a hermetic glass DO-35 package with cathode band polarity marking, Sn96.5Ag3.5 lead finish, and J-STD-020 Level 1 moisture sensitivity. Thermal resistance is 300 °C/W (junction-to-ambient), with power derating required above 75 °C lead temperature.

Key Specifications

Pinout & Package

Package: DO-35 glass axial-leaded hermetic case, 0.13 g mass, cathode indicated by black band. Dimensions: A ≤ 25.4 mm, B ≤ 4.0 mm, C ≤ 0.6 mm, D ≤ 2.0 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMSZ5222B, the 1N5222B-T offers higher power rating (500 mW vs. 200 mW) and through-hole mounting flexibility, while 1N4728A provides different voltage and power trade-offs-neither matches both electrical and mechanical equivalence.

Availability

1N5222B-T is available at Aetrix Electronics and suitable for power supply feedback, overvoltage clamp, reference voltage source, and current source bias applications requiring stable component supply despite end-of-life status.

Supply support for 1N5222B-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 general-purpose voltage regulation and reference in cost-sensitive, high-reliability industrial and consumer electronics.

FAQ

Is the 1N5222B-T still in active production?

No, the 1N5222B-T is officially obsolete and discontinued by Diodes Incorporated as of September 2019. It is superseded by the MMSZ5222B surface-mount equivalent. Aetrix Electronics maintains limited legacy stock for design continuity and repair programs, with full traceability and RoHS compliance documentation.

What is the maximum allowable reverse voltage before breakdown?

The 1N5222B-T begins controlled Zener breakdown at its nominal 2.5 V, with guaranteed regulation between 2.38 V and 2.63 V at 20 mA. Applying reverse voltage below 2.38 V results in negligible leakage (<100 µA at 1.0 V); exceeding 2.63 V risks thermal runaway if power dissipation exceeds 500 mW without adequate heat sinking.

Can this diode be used in AC signal clipping applications?

Yes, the 1N5222B-T functions as a bidirectional clipper when paired with a second diode in series opposition. In that configuration, it clips positive half-cycles at +2.5 V and negative half-cycles at -1.1 V (forward V_F), enabling symmetrical or asymmetrical waveform limiting in audio and sensor signal conditioning circuits.

How does the DO-35 package affect thermal performance in PCB layouts?

The DO-35's glass axial construction has 300 °C/W junction-to-ambient thermal resistance when leads are 9.5 mm long and held at ≤75 °C. To maintain rated 500 mW dissipation, minimize copper pad area on both ends, avoid thermal vias near leads, and ensure ≥2 mm clearance from adjacent heat sources to prevent localized ambient temperature rise.