onsemi BZX85C43_T50A

Overview

BZX85C43_T50A from onsemi is a 43 V, ±5% tolerance, 1.0 W axial-leaded Zener diode in DO-41 glass package, rated for 50 mA zener test current (IZ), with 6 Ω dynamic impedance (ZZ) at IZ and 0.25 μA maximum leakage current (IR) at 30 V reverse voltage - used for precision voltage regulation and overvoltage protection in DC power supplies and reference circuits.

For engineers reviewing the BZX85C43_T50A datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage tolerance, power derating above 50°C, thermal resistance, cathode band identification, and compatibility with through-hole PCB assembly for industrial linear regulators and analog signal conditioning.

Technical Context

This device operates as a silicon planar Zener diode optimized for stable voltage reference and clamping in low-to-medium power applications. It maintains regulation across a 5–100 mA operating current range with specified 6 Ω impedance at 50 mA and 1000 Ω impedance at 1 mA (ZZK).

The DO-41 glass package provides hermetic sealing and thermal performance suitable for operation from −65°C to +200°C. Power dissipation is rated at 1.0 W at 25°C ambient, derating linearly by 6.67 mW/°C above 50°C, with 1.3 W capability at 25°C lead temperature (TL) measured at 4 mm from package.

Key Specifications

Pinout & Package

DO-41 glass axial package with cathode identified by a single color band near one lead end. Leads are tinned copper-clad steel, compatible with wave and hand soldering per J-STD-001.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX85C43_T50A, the 1N4749A offers nearly identical electrical behavior with marginal impedance trade-off, while the BZX55C43 reduces power handling and requires physical redesign - making BZX85C43_T50A optimal for robust 1 W regulation in standard through-hole layouts.

Availability

BZX85C43_T50A is available at Aetrix Electronics and suitable for DC power supply regulation, overvoltage protection clamps, and precision voltage reference applications requiring stable component supply across automotive, industrial control, and test equipment programs.

Supply support for BZX85C43_T50A 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 delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The BZX85C series belongs to onsemi's general-purpose Zener diode product line, engineered for reliable voltage regulation and transient suppression in cost-sensitive, high-volume analog circuits where DO-41 mechanical robustness and wide temperature operation are essential.

FAQ

What is the zener voltage tolerance of BZX85C43_T50A?

The BZX85C43_T50A has a guaranteed zener voltage range of 40 V to 46 V at 50 mA test current, corresponding to a ±5% tolerance. This tolerance is verified per the onsemi datasheet Rev. 2 (October 2017) and applies across the full operating temperature range of −65°C to +200°C. The BZX85C43_T50A achieves this consistency using planar diffusion process control and glass-package hermeticity.

Can BZX85C43_T50A be used in surface-mount designs?

No, the BZX85C43_T50A is exclusively offered in the axial DO-41 glass package and is not available in SMD variants such as SOD-123 or DO-213AB. Its leads require through-hole mounting with 0.4–0.6 mm diameter holes and 2.72–2.03 mm lead spacing. For surface-mount alternatives, engineers should evaluate the NZ9F43V or MMBZ5257B, which are not direct replacements for BZX85C43_T50A.

What is the maximum allowable reverse voltage before breakdown for BZX85C43_T50A?

The BZX85C43_T50A begins regulating at its nominal zener voltage (40–46 V), but its absolute maximum non-destructive reverse voltage is defined by its power limit and thermal design. At 25°C ambient, it can sustain up to 46 V continuously at ≤21.7 mA (1.0 W / 46 V); beyond that, junction temperature rise must be managed. The device does not specify a separate "breakdown threshold" - regulation starts gradually near 40 V and stabilizes above 43 V at rated current.

How does the derating curve affect BZX85C43_T50A's usable power at 85°C ambient?

At 85°C ambient, BZX85C43_T50A's usable power is reduced to 0.767 W: derating begins at 50°C at 6.67 mW/°C, so (85 − 50) × 6.67 mW = 233.45 mW reduction from 1.0 W → 766.55 mW. This reflects real-world thermal constraints in enclosed power supplies. The BZX85C43_T50A remains functional up to +200°C junction temperature, but sustained operation above 125°C ambient requires heatsinking or forced airflow.

Is BZX85C43_T50A RoHS compliant and halogen-free?

Yes, BZX85C43_T50A meets RoHS Directive 2011/65/EU and is halogen-free per onsemi's material declarations. The DO-41 glass package contains no lead in solderable terminations (lead-free tinning), and all internal materials comply with IEC 61249-2-21. Compliance documentation for BZX85C43_T50A is available via onsemi's Quality & Environmental page and is tracked under material category "Discrete Semiconductors – Zener Diodes".