onsemi 1N5997B_T50R

Overview

1N5997B_T50R from Fairchild Semiconductor is a 7.5 V ±5% Zener diode in DO-35 glass package, rated for 500 mW power dissipation at TL ≤ 75°C with 7 Ω zener impedance at 5 mA test current and 0.5 mA maximum leakage current at 6 V reverse voltage. It serves as a precision voltage reference or overvoltage clamp in low-power analog circuits.

For engineers reviewing the 1N5997B_T50R datasheet, pinout, applications, or equivalent options, key selection criteria include its 7.5 V nominal zener voltage, 5 mA test current, DO-35 mechanical compatibility, thermal derating slope (4.0 mW/°C above 75°C), and 0.5 mA IR at VR = 6 V - all critical for stable biasing and regulation in space-constrained designs.

Technical Context

This device operates in reverse breakdown mode with a tightly controlled 7.125 V to 7.875 V zener voltage window at 5 mA, defined by its ±5% tolerance. Its low dynamic impedance (7 Ω @ IZ) ensures minimal output voltage variation under load changes.

The 1N5997B_T50R exhibits 600 Ω knee impedance (ZZK) at 250 μA and maintains 0.5 mA leakage current up to 6 V reverse bias, enabling reliable clamping in signal conditioning and power supply feedback paths without excessive standby loss.

Key Specifications

Pinout & Package

DO-35 glass axial package with cathode indicated by color band; two-terminal device requiring no orientation-specific PCB footprint beyond standard 0.375" (9.5 mm) lead spacing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N5997B_T50R, the 1N5236B offers identical voltage rating but requires different thermal derating assumptions, while BZX55-C7V5 delivers lower leakage and impedance at the cost of reduced surge current capability - making each suitable for distinct thermal or power-budget constraints.

Availability

1N5997B_T50R is available at Aetrix Electronics and suitable for voltage reference design, overvoltage protection, and linear regulator feedback applications requiring stable component supply and long-term obsolescence mitigation.

Supply support for 1N5997B_T50R 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.

The 1N5997B_T50R belongs to Fairchild's legacy 1N59xxB Zener diode family, engineered for general-purpose voltage regulation and clamping in industrial, automotive, and consumer electronics where DO-35 reliability and ±5% tolerance were essential.

FAQ

What is the exact zener voltage range for 1N5997B_T50R at 5 mA test current?

The 1N5997B_T50R has a guaranteed zener voltage range of 7.125 V to 7.875 V at 5 mA test current and 25°C ambient, reflecting its ±5% tolerance specification. This window remains valid under thermal equilibrium conditions with 3/8" lead length and TL ≤ 75°C, as defined in the Fairchild datasheet Rev. C2.

Does 1N5997B_T50R support operation above 75°C ambient temperature?

Yes, the 1N5997B_T50R operates from −65°C to +200°C, but its power dissipation must be derated linearly at 4.0 mW/°C above 75°C lead temperature. At 100°C TL, maximum allowable PD drops to 400 mW; full 500 mW is only permitted when lead temperature stays at or below 75°C.

How does the leakage current of 1N5997B_T50R compare to similar 7.5 V Zeners?

The 1N5997B_T50R specifies 0.5 mA maximum leakage current at 6 V reverse voltage, which is higher than BZX55-C7V5 (0.1 mA) but aligned with industry-standard 7.5 V Zeners like 1N5236B (0.5 mA). This level avoids significant error in high-impedance reference nodes while maintaining robust surge handling.

Is the DO-35 package of 1N5997B_T50R compatible with automated through-hole assembly?

Yes, the DO-35 package of 1N5997B_T50R features standardized 0.375" (9.5 mm) lead spacing and axial symmetry, supporting wave soldering and selective soldering processes. Its glass body requires standard preheat profiles to avoid thermal shock, consistent with IPC-J-STD-020 guidelines for moisture-sensitive discrete devices.

Can 1N5997B_T50R be used as a forward-biased diode in addition to zener operation?

Yes, the 1N5997B_T50R supports forward conduction with VF ≤ 1.2 V at 200 mA, enabling dual-use in circuits requiring both polarity protection and voltage clamping. However, its forward surge rating is not specified separately, so repetitive forward current should remain within its 500 mW power limit under thermal consideration.