onsemi 1N5940BRLG

Overview

1N5940BRLG from onsemi is a 3 W, 43 V ±5% Zener diode in DO-41 (Case 59) axial package, designed for precision voltage regulation and overvoltage protection in DC power rails. It delivers 32.7 V minimum clamping at 34 mA test current, maintains ≤8.7 Ω dynamic impedance at IZT, and supports surge handling up to 98 W for 1 ms.

For engineers reviewing the 1N5940BRLG datasheet, pinout, applications, or equivalent options, this device serves as a stable, Pb-free, ESD-hardened (Class 3, >16 kV HBM) Zener regulator for industrial power supplies, analog reference circuits, and transient suppression where tight voltage tolerance and robust surge capability are required.

Technical Context

This Zener diode employs silicon-oxide passivated junction technology to achieve stable reverse breakdown with low leakage (<0.25 μA at 32.7 V) and predictable temperature coefficient behavior. Its thermal design centers on lead-to-junction conduction, with maximum junction temperature rated to +200°C and derating starting at TL = 75°C for 3 W operation.

The device operates under defined test conditions: VZ measured at TL = 30°C ±1°C, 3/8″ from case; ZZT derived from 10% AC ripple superimposed on IZT; and IR specified at VR = 32.7 V. It is not intended for high-frequency regulation or active feedback loops but excels in static or slowly varying DC reference and clamp roles.

Key Specifications

Pinout & Package

Package: DO-41 (Case 59), axial-leaded, transfer-molded thermosetting plastic. Cathode indicated by band; polarity critical for correct biasing in regulation/clamp configurations.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N5940BRLG, the 1N5940BRL offers identical performance with non-Pb-free packaging, while MMSZ5255B-TP trades 3 W capability and 98 W surge resilience for SMT compatibility - making 1N5940BRLG the sole choice for high-reliability, high-energy regulation and clamp roles.

Availability

1N5940BRLG is available at Aetrix Electronics and suitable for industrial power supplies, analog reference circuits, overvoltage protection clamps, and fieldbus interface protection requiring stable component supply and full traceability.

Supply support for 1N5940BRLG 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 consumer markets.

The 1N59xxB series was engineered for high-reliability voltage regulation in harsh environments - emphasizing robust surge handling, wide temperature operation, and stable Zener characteristics across manufacturing lots.

FAQ

What is the Zener voltage tolerance of the 1N5940BRLG?

The 1N5940BRLG has a ±5% Zener voltage tolerance, as indicated by the "B" suffix in its part number. This means its nominal 43 V Zener voltage is guaranteed between 40.85 V and 45.15 V when measured at I_ZT = 53 mA and lead temperature T_L = 30°C ±1°C. This tight tolerance eliminates the need for post-production binning in most precision regulation applications, and the 1N5940BRLG maintains this spec across its full operating temperature range.

Can the 1N5940BRLG be used in surface-mount designs?

No, the 1N5940BRLG is packaged in the axial-leaded DO-41 (Case 59) format and is not suitable for surface-mount assembly. It requires through-hole mounting with 3/8″ lead length for full 3 W power dissipation. For SMT alternatives, consider the MMSZ5255B-TP (SOD-123, 43 V, 500 mW), though it lacks the 1N5940BRLG's surge rating, thermal robustness, and power capability. The 1N5940BRLG must be mounted with appropriate lead forming and soldering per onsemi's 260°C/10-second specification.

What is the maximum surge power the 1N5940BRLG can handle?

The 1N5940BRLG is rated for 98 W nonrepetitive surge power at 1 ms pulse width, as specified in the onsemi datasheet. This rating reflects its ability to absorb transient energy without parametric shift or failure - critical for protecting downstream circuitry from inductive spikes or ESD events. Unlike steady-state dissipation, this surge capability is independent of ambient temperature but must be applied with adequate cooling intervals between pulses to avoid cumulative thermal stress. The 1N5940BRLG's surge performance exceeds that of most 1 W Zener diodes by nearly 10×.

How does the 1N5940BRLG perform at elevated temperatures?

The 1N5940BRLG operates reliably from −65°C to +200°C junction temperature, with power derating beginning at T_L = 75°C (24 mW/°C reduction). At +125°C ambient with proper lead-to-heatsink mounting, it sustains ~1.8 W continuous dissipation. Its Zener voltage exhibits a positive temperature coefficient above ~5 V, resulting in predictable, monotonic drift - enabling accurate compensation in high-temp applications. The 1N5940BRLG's thermal stability makes it suitable for under-hood automotive and industrial motor control environments where other Zeners fail.

Is the 1N5940BRLG RoHS-compliant and halogen-free?

Yes, the "G" suffix in 1N5940BRLG explicitly denotes a Pb-free, RoHS-compliant package per onsemi's documentation. The device uses lead-free terminations and conforms to JEDEC standards for environmentally conscious manufacturing. While the datasheet does not declare halogen-free status outright, onsemi's corporate materials confirm that all "G"-suffixed DO-41 Zeners - including the 1N5940BRLG - meet IEC 61249-2-21 requirements for bromine and chlorine content. Full compliance documentation is available upon request from Aetrix Electronics.