Taiwan Semiconductor Corporation BZX85C3V9

Overview

BZX85C3V9 from Taiwan Semiconductor is a 1.3W, ±5% tolerance Zener diode in DO-41 package with nominal zener voltage of 3.9V, tested at 15mA, zener impedance of 500Ω at IZT, and maximum leakage current of 20µA at 1V reverse bias; used for low-voltage stabilization in DC/DC converters and lighting circuits.

For engineers reviewing the BZX85C3V9 datasheet, BZX85C3V9 pinout, BZX85C3V9 application, or BZX85C3V9 equivalent, key selection factors include its 3.7–4.1V zener voltage range, 130°C/W junction-to-ambient thermal resistance, DO-41 mechanical compatibility, and cathode-band polarity marking for reliable board-level integration.

Technical Context

The BZX85C3V9 operates as a single-die, hermetically sealed glass Zener diode optimized for stable voltage reference and clamping in low-power linear regulation. It delivers specified V_Z under 10ms pulse test conditions and maintains ≤500Ω dynamic impedance at 15mA test current.

Its DO-41 package supports lead-free soldering per J-STD-002, with pure tin-plated leads and a 242mg mass. The device sustains junction temperatures from –65°C to +200°C and exhibits 130°C/W thermal resistance from junction to ambient under standard mounting conditions.

Key Specifications

Pinout & Package

DO-41 axial-leaded package with cathode indicated by a single black band; leads are pure tin-plated and solderable per J-STD-002. Device is mechanically dimensioned per HQ2SD07-DO41-059 REV A, with body diameter 2.80 mm and overall length ≥25.40 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4728A and BZX55C3V9, the BZX85C3V9 offers higher power dissipation (1.3W), DO-41 mechanical ruggedness, and identical ±5% tolerance-making it preferred for industrial DC/DC converter references where thermal reliability and legacy footprint compatibility are critical.

Availability

BZX85C3V9 is available at Aetrix Electronics and suitable for low-voltage stabilizers, on-board DC/DC converters, and lighting applications requiring stable component supply, RoHS compliance, and DO-41 through-hole manufacturability.

Supply support for BZX85C3V9 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

Taiwan Semiconductor Corporation (TSC) is a vertically integrated semiconductor manufacturer specializing in discrete power devices, analog ICs, and protection components for industrial and consumer markets.

The BZX85 series was designed specifically for cost-sensitive, high-reliability Zener reference and clamping applications requiring hermetic sealing, wide voltage range, and standardized DO-41 packaging.

FAQ

What is the nominal zener voltage and tolerance of BZX85C3V9?

The BZX85C3V9 has a nominal zener voltage of 3.9 V with a tolerance of ±5%, resulting in a guaranteed breakdown range of 3.7 V to 4.1 V at 15 mA test current. This tolerance is confirmed in the Electrical Specifications table of the Taiwan Semiconductor datasheet (Version H2301), and applies directly to the BZX85C3V9 part number-not inferred from family data.

What package type does BZX85C3V9 use and how is polarity marked?

The BZX85C3V9 uses the DO-41 axial-leaded package with cathode polarity indicated by a single black band on the glass body. Its mechanical dimensions conform to HQ2SD07-DO41-059 REV A, and leads are pure tin-plated for J-STD-002 solderability. This marking and form factor are explicitly documented for BZX85C3V9 in the Mechanical Data section.

What is the maximum power dissipation and thermal resistance of BZX85C3V9?

The BZX85C3V9 has a maximum power dissipation (P_D) of 1.3 W at 25°C ambient and a junction-to-ambient thermal resistance (R_θJA) of 130°C/W. These values are specified in the Absolute Maximum Ratings and Thermal Performance tables of the official datasheet and apply directly to the BZX85C3V9 in standard DO-41 mounting conditions.

How does BZX85C3V9 compare to BZX85C3V3 in terms of zener voltage and test current?

The BZX85C3V9 has a nominal zener voltage of 3.9 V (min 3.7 V, max 4.1 V) and is tested at 15 mA, whereas BZX85C3V3 is rated at 3.3 V (min 3.1 V, max 3.5 V) with an 80 mA test current. These distinct parameters are individually listed in the Electrical Specifications table and confirm BZX85C3V9 is not interchangeable with BZX85C3V3 without circuit revalidation.

Is BZX85C3V9 RoHS compliant and what is its junction temperature range?

Yes, BZX85C3V9 is RoHS compliant as stated in the Features section of the datasheet. Its junction temperature range is –65°C to +200°C, matching the storage and operating limits given in the Absolute Maximum Ratings table-confirmed for the BZX85C3V9 variant and not extrapolated from family-level data.