onsemi 1N5997B_T50A

Overview

1N5997B_T50A 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 4.0 mW/°C derating, 7 Ω typical zener impedance at 5 mA test current, and 0.5 mA maximum leakage current at 6 V reverse voltage. It provides precision voltage regulation in low-power analog reference and overvoltage protection circuits.

For engineers reviewing the 1N5997B_T50A datasheet, pinout, applications, or equivalent options, this page delivers verified electrical parameters, thermal limits, DO-35 terminal mapping, real-world use cases, and two validated alternative Zeners with documented differences in voltage tolerance, impedance, and leakage behavior.

Technical Context

This device operates as a silicon planar Zener diode optimized for stable voltage reference and clamping in DC bias networks. Its 7.5 V nominal breakdown voltage is specified at 5 mA test current, with tight 5% tolerance and low dynamic impedance (7 Ω typ.) ensuring minimal output variation under load changes.

The DO-35 glass package supports operation from –65°C to +200°C junction temperature, with thermal derating beginning at 75°C lead temperature. Forward voltage is limited to 1.2 V max at 200 mA, confirming suitability for bidirectional protection and low-loss rectification roles where needed.

Key Specifications

Pinout & Package

DO-35 glass axial package with cathode indicated by color band; anode and cathode terminals are unidirectional, non-polarized except for marking orientation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N5997B_T50A, the 1N4734A trades tighter voltage control for broader availability and lower cost, while the BZX55C7V5 matches tolerance and package but exhibits higher dynamic impedance-making 1N5997B_T50A optimal for high-stability analog references requiring sub-10 Ω regulation resistance.

Availability

1N5997B_T50A is available at Aetrix Electronics and suitable for power supply reference, overvoltage clamp, and low-power analog sensor excitation applications requiring stable component supply, long-term lifecycle support, and traceable DO-35 Zener diodes.

Supply support for 1N5997B_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

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; its legacy Zener diode portfolio remains widely deployed in industrial and automotive systems.

The 1N59xxB series was designed for general-purpose voltage regulation and transient suppression in space-constrained, thermally demanding applications-emphasizing DO-35 reliability, wide temperature operation, and consistent 5% tolerance across the 2.4–100 V range.

FAQ

What is the exact Zener voltage range for 1N5997B_T50A?

The 1N5997B_T50A has a guaranteed Zener voltage range of 7.125 V to 7.875 V at 5 mA test current, reflecting its ±5% tolerance specification. This range is measured under thermal equilibrium conditions at 30°C ±1°C lead temperature with 3/8″ lead length, per Fairchild's Rev. C2 datasheet. The typical value is 7.5 V, and deviations outside this window indicate nonconformance.

Does 1N5997B_T50A support operation above 100°C ambient?

Yes, the 1N5997B_T50A supports junction temperatures up to +200°C and storage down to –65°C. At ambient temperatures above 75°C, power dissipation must be linearly derated at 4.0 mW/°C. For example, at 125°C ambient, maximum allowable power drops to 300 mW. Thermal design must account for lead-to-PCB conduction and ambient airflow per DO-35 mounting guidelines.

What is the maximum leakage current specification for 1N5997B_T50A?

The 1N5997B_T50A specifies a maximum leakage current (I_R) of 0.5 mA at 6 V reverse voltage (V_R). This value is measured at 25°C and defines the upper bound of unwanted current flow in high-impedance bias networks. At lower voltages (e.g., 4 V), leakage falls below 100 µA, supporting ultra-low-power sensor excitation applications.

Is 1N5997B_T50A compatible with lead-free reflow soldering?

Yes, the DO-35 glass package of the 1N5997B_T50A is rated for lead-free reflow profiles per J-STD-020. Peak temperature exposure up to 260°C for 10 seconds is permitted. Preheating to 150°C for 90–120 seconds and ramp rates ≤3°C/s are recommended to avoid thermal shock cracking of the glass body during assembly.

How does the zener impedance of 1N5997B_T50A affect regulation performance?

The 1N5997B_T50A exhibits 7 Ω typical zener impedance (Z_Z) at 5 mA, meaning a 1 mA change in load current produces only ~7 mV output shift. This low impedance ensures stable regulation in analog references and feedback loops where supply ripple rejection and line/load regulation are critical-outperforming higher-impedance alternatives like the 1N4734A (17 Ω) in precision applications.