onsemi 1N5373B

Overview

1N5373B from onsemi is a 5 W axial-lead Zener diode with nominal zener voltage of 68 V, ±5% tolerance, maximum zener impedance of 20 Ω at 44 mA test current, and surge rating of 500 A at 8.3 ms. It operates as a precision voltage reference or overvoltage clamp in DC power supply regulation circuits.

For engineers reviewing the 1N5373B datasheet, pinout, applications, or equivalent options, key selection criteria include its 68 V nominal breakdown, 5 W steady-state power dissipation, 20 Ω dynamic impedance, low leakage (1.52 mA @ 51.7 V), and axial plastic package (Case 017AA) suitable for through-hole PCB mounting and industrial power conditioning.

Technical Context

The 1N5373B employs silicon-oxide passivated junction technology to achieve tight voltage tolerance (±5%), stable temperature coefficient (~0.11 %/°C above 6.2 V), and high ESD robustness (>16 kV HBM). Its thermal design relies on lead-to-ambient conduction, with junction-to-lead resistance of 25 °C/W at 3/8″ lead length.

It delivers regulated voltage under reverse-bias conditions with specified test currents (IZT = 44 mA, IZK = 1 mA), exhibits low dynamic impedance (20 Ω @ IZT), and maintains <1.52 mA leakage at VR = 51.7 V - enabling reliable clamping in transient-suppression and reference circuits across −65°C to +150°C continuous operation.

Key Specifications

Pinout & Package

1N5373B uses an axial-lead, transfer-molded plastic package (Case 017AA) with cathode indicated by a painted band. Leads are solderable, corrosion-resistant, and rated for 260°C for 10 seconds at 1/16″ from case.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N5373 and MMBZ5263B, the 1N5373B provides superior voltage stability (±5% vs. ±10% or unspecified), higher surge resilience (500 A vs. no published surge rating), and verified 5 W thermal capability - making it the only option qualified for industrial-grade shunt regulation at 68 V.

Availability

1N5373B is available at Aetrix Electronics and suitable for industrial DC power supplies, motor drive protection circuits, test equipment reference designs, and telecom line interface surge suppression requiring stable component supply and long-lifecycle support.

Supply support for 1N5373B 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and IoT applications.

The 1N53 series belongs to onsemi's Surmetic™ 40 Zener regulator family, engineered for high-reliability voltage reference and transient suppression in harsh-environment power systems where precision, surge resilience, and thermal stability are essential.

FAQ

What is the nominal zener voltage and tolerance of the 1N5373B?

The 1N5373B has a nominal zener voltage of 68 V with a guaranteed tolerance of ±5%, meaning its actual breakdown voltage falls between 64.6 V and 71.4 V at 44 mA test current. This tight tolerance is confirmed in the onsemi datasheet Rev. 19 (July 2024) and reflects the device's use of silicon-oxide passivated junction technology. The 1N5373B is specifically designed for applications demanding stable voltage references without post-manufacturing trimming.

What is the maximum steady-state power dissipation for the 1N5373B?

The 1N5373B is rated for a maximum steady-state power dissipation of 5 W at a lead temperature (TL) of 25°C, with thermal derating of 40 mW/°C above that temperature. This rating assumes 3/8″ lead length and is validated per onsemi's test conditions. The 1N5373B achieves this performance in its axial plastic Case 017AA package, which provides sufficient thermal path via leads for conduction cooling in standard PCB layouts.

Does the 1N5373B have a specified surge current rating?

Yes, the 1N5373B has a specified non-repetitive peak surge current rating of 500 A at an 8.3 ms pulse width, per onsemi's datasheet Figure 5 and Table on page 3. This rating is derived from its 180 W surge capability and is validated under standardized square-wave testing. The 1N5373B leverages its robust silicon-oxide junction to absorb such transients without parameter shift, making it suitable for industrial surge suppression where IEC 61000-4-5 compliance is required.

What is the zener impedance of the 1N5373B and why does it matter?

The 1N5373B has a maximum zener impedance (ZZT) of 20 Ω measured at its 44 mA test current (IZT). This low dynamic impedance ensures minimal output voltage deviation under varying load currents - critical for maintaining regulation accuracy in power supply feedback loops or precision reference circuits. The 1N5373B's 20 Ω value is significantly lower than many general-purpose Zeners, directly supporting stable performance in closed-loop regulation schemes.

Is the 1N5373B RoHS-compliant and what package type does it use?

Yes, the 1N5373B is RoHS-compliant and supplied in a Pb-free axial-lead plastic package designated Case 017AA. Its markings include the "G" suffix to indicate Pb-free construction, and its mechanical outline meets onsemi's SURMETIC™ 40 specifications. The package features corrosion-resistant leads, void-free transfer-molded thermosetting plastic, and a cathode band for polarity identification - all optimized for automated through-hole assembly and long-term reliability in humid or chemically aggressive environments.