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Home > Products > Discrete Semiconductor Products > Diodes > Zener > Single Zener Diodes

onsemi 1N5987B_T50A

Name: 1N5987B_T50A
Brand: onsemi
SKU: 1N5987B_T50A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 1N5987B_T50A

Manufacturer:: onsemi

Category:: Single Zener Diodes

Package:: DO-204AH, DO-35, Axial

Datasheet:: 1N5987B_T50A.pdf

Description:: DIODE ZENER 3V 500MW DO35

Quantity:: RFQ Add To RFQ list

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Product details

Overview

1N5987B_T50A from Fairchild Semiconductor is a 3.0 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, 95 Ω zener impedance at 5 mA test current, and 50 μA leakage current at 1.0 V reverse voltage. It provides precision voltage reference and overvoltage protection in low-power analog circuits.

For engineers reviewing the 1N5987B_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 - all confirmed from Fairchild's Rev. C2 datasheet.

Technical Context

The 1N5987B_T50A operates as a silicon planar Zener diode with sharp reverse breakdown at nominal 3.0 V, specified under thermal equilibrium conditions (TL = 30°C ±1°C, 3/8″ lead length). Its 95 Ω dynamic impedance at 5 mA ensures stable regulation across moderate load variations.

It features a maximum operating junction temperature of +200°C and storage range from –65°C to +200°C, with forward voltage limited to 1.2 V at 200 mA. Leakage current remains ≤50 μA up to 1.0 V reverse bias, supporting low-quiescent-current designs.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	3.0 V nominal, min 2.85 V / max 3.15 V at 5 mA - defines precise clamping threshold for 3.3 V rail protection
Power Dissipation (P_D)	500 mW @ TL ≤ 75°C - sets maximum continuous power handling on PCB with standard lead length
Zener Impedance (Z_Z)	95 Ω @ I_Z = 5 mA - determines output voltage variation under load current changes
Leakage Current (I_R)	50 μA @ V_R = 1.0 V - ensures minimal standby current in battery-powered sensing nodes
Max Zener Current (I_ZM)	167 mA - derived from P_D/V_Z, sets absolute peak surge capability before thermal runaway
Operating Temp Range	–65°C to +200°C - supports deployment in automotive engine compartments and industrial motor controls

Pinout & Package

DO-35 glass axial package with cathode indicated by color band; leads are unmarked anode/cathode terminals suitable for through-hole mounting. Total body length: 4.0–4.5 mm, diameter: 1.8–2.2 mm.

Pin/Terminal	Circuit Role	Design Meaning
Anode (unbanded end)	Forward conduction terminal	Connected to lower-potential node during reverse-bias regulation; carries full load current in shunt configuration
Cathode (banded end)	Zener breakdown terminal	Connected to higher-potential node; establishes regulated reference voltage at cathode-to-anode drop

Key Features

Feature	Design Value
±5% Zener voltage tolerance	Enables direct replacement in legacy 3.3 V supply monitoring without recalibration
Low 95 Ω dynamic impedance	Maintains <±25 mV output deviation across 1–10 mA load shifts in feedback loops
DO-35 glass encapsulation	Provides hermetic seal and high reliability in humid or chemically aggressive environments
200°C max junction temperature	Permits operation adjacent to heat-generating components without derating in compact layouts

Applications

Voltage Reference for ADC Biasing	Overvoltage Clamp in RS-232 Receivers
Use Scenario: Providing stable 3.0 V reference to bias the input stage of a 12-bit SAR ADC in a data acquisition module. IC Role / Device Role / Timing Role: Shunt voltage reference establishing precise analog ground offset for signal conditioning circuitry. Use Value: 95 Ω Z_Z and ±5% V_Z ensure reference drift remains within 0.5 LSB error across temperature.	Use Scenario: Protecting the receiver input of a MAX232-compatible transceiver from ESD-induced transients exceeding ±15 V. IC Role / Device Role / Timing Role: Passive overvoltage clamp limiting input voltage to safe levels during fast-rising surges. Use Value: 500 mW rating and 167 mA I_ZM absorb single-event pulses without degradation.
Low-Power Sensor Excitation	Microcontroller Reset Threshold Control
Use Scenario: Supplying excitation voltage to a 1 kΩ resistive temperature detector (RTD) in a battery-operated environmental sensor. IC Role / Device Role / Timing Role: Precision current source via series resistor + Zener shunt, delivering stable 3.0 V bias. Use Value: 50 μA I_R at 1.0 V minimizes quiescent drain on coin-cell batteries during sleep mode.	Use Scenario: Setting brown-out detection threshold for an ARM Cortex-M0+ MCU operating from a 3.3 V LDO. IC Role / Device Role / Timing Role: Zener-based comparator reference enabling reset assertion below 2.85 V. Use Value: Min V_Z = 2.85 V directly matches common 3.3 V MCU reset window requirements.

Voltage Reference for ADC Biasing

Overvoltage Clamp in RS-232 Receivers

Use Scenario: Providing stable 3.0 V reference to bias the input stage of a 12-bit SAR ADC in a data acquisition module.

IC Role / Device Role / Timing Role: Shunt voltage reference establishing precise analog ground offset for signal conditioning circuitry.

Use Value: 95 Ω Z_Z and ±5% V_Z ensure reference drift remains within 0.5 LSB error across temperature.

Use Scenario: Protecting the receiver input of a MAX232-compatible transceiver from ESD-induced transients exceeding ±15 V.

IC Role / Device Role / Timing Role: Passive overvoltage clamp limiting input voltage to safe levels during fast-rising surges.

Use Value: 500 mW rating and 167 mA I_ZM absorb single-event pulses without degradation.

Low-Power Sensor Excitation

Microcontroller Reset Threshold Control

Use Scenario: Supplying excitation voltage to a 1 kΩ resistive temperature detector (RTD) in a battery-operated environmental sensor.

IC Role / Device Role / Timing Role: Precision current source via series resistor + Zener shunt, delivering stable 3.0 V bias.

Use Value: 50 μA I_R at 1.0 V minimizes quiescent drain on coin-cell batteries during sleep mode.

Use Scenario: Setting brown-out detection threshold for an ARM Cortex-M0+ MCU operating from a 3.3 V LDO.

IC Role / Device Role / Timing Role: Zener-based comparator reference enabling reset assertion below 2.85 V.

Use Value: Min V_Z = 2.85 V directly matches common 3.3 V MCU reset window requirements.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
1N4728A (ON Semiconductor)	3.3 V nominal, ±5%, 1.0 W rating, DO-41 package	Higher power and larger footprint; requires PCB layout revision	Select when >500 mW surge energy absorption is required and board space permits DO-41
BZX55C3V0 (Vishay)	3.0 V nominal, ±5%, 500 mW, DO-35, 100 Ω Z_Z @ 5 mA	Nearly identical specs; minor Z_Z increase (100 Ω vs. 95 Ω) has negligible impact on regulation accuracy	Drop-in substitute with same DO-35 mechanical fit and matching electrical envelope

Compared with 1N5987B_T50A, the BZX55C3V0 offers functionally identical voltage regulation in the same package with only a 5 Ω higher dynamic impedance, while the 1N4728A trades compactness for higher power handling - making the former ideal for footprint-constrained replacements and the latter for thermally demanding transient suppression.

Availability

1N5987B_T50A is available at Aetrix Electronics and suitable for voltage reference design, overvoltage protection, and low-power sensor excitation requiring stable component supply across industrial control, test equipment, and embedded instrumentation programs.

Supply support for 1N5987B_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 Zener diodes were widely adopted for industrial reliability.

The 1N5985B–1N6025B family was engineered for precision voltage regulation in cost-sensitive, high-volume applications where tight tolerance, stable impedance, and wide temperature operation were critical - especially in legacy industrial and telecom infrastructure.

FAQ

What is the exact Zener voltage tolerance for 1N5987B_T50A?

The 1N5987B_T50A has a guaranteed Zener voltage tolerance of ±5% around its nominal 3.0 V rating, meaning measured V_Z falls between 2.85 V and 3.15 V when tested at 5 mA and TL = 30°C ±1°C. This tolerance is explicitly defined in Fairchild's Rev. C2 datasheet Table 1 and applies to every unit shipped under this part number.

Can 1N5987B_T50A be used in surface-mount designs?

No - the 1N5987B_T50A uses a DO-35 glass axial package with radial leads intended for through-hole mounting. It lacks solder pads or terminations compatible with reflow or wave soldering processes. For SMT equivalents, consider the MMBZ5226B (SOT-23, 3.3 V) or BZX384-C3V0 (SOD-323), but note these differ in voltage, power, and impedance from the 1N5987B_T50A.

What is the maximum allowable reverse voltage before breakdown for 1N5987B_T50A?

The 1N5987B_T50A begins controlled Zener breakdown at its specified V_Z of 3.0 V (min 2.85 V). Below this, leakage remains ≤50 μA up to 1.0 V reverse bias. Applying reverse voltage above 3.15 V initiates regulation - not damage - provided power dissipation stays within 500 mW and thermal limits are observed.

How does thermal derating affect 1N5987B_T50A's power handling above 75°C?

Above 75°C lead temperature, the 1N5987B_T50A must be derated at 4.0 mW/°C. At 100°C TL, its usable power drops to 400 mW (500 mW – [25°C × 4.0 mW/°C]). This linear derating curve is defined in the Absolute Maximum Ratings table and must be applied in thermal simulations for enclosed or high-ambient environments.

Is forward voltage specified for 1N5987B_T50A, and what is its value?

Yes - Fairchild specifies a maximum forward voltage (V_F) of 1.2 V for the 1N5987B_T50A at I_F = 200 mA. This parameter is relevant when the device is used in forward conduction (e.g., as a series diode), though its primary function is reverse-bias Zener regulation. The value appears in the "Electrical Characteristics" summary on page 3 of the Rev. C2 datasheet.

1N5987B_T50A Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: DO-204AH, DO-35, Axial

Packaging:: Tape & Box (TB)

Product Status:: Obsolete

Voltage - Zener (Nom) (Vz):: 3 V

Tolerance:: ±5%

Power - Max:: 500 mW

Impedance (Max) (Zzt):: 95 Ohms

Current - Reverse Leakage @ Vr:: 50 µA @ 1 V

Voltage - Forward (Vf) (Max) @ If:: 1.2 V @ 200 mA

Operating Temperature:: -65°C ~ 200°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: DO-35

1N5987B_T50A FAQ

1.How can I place an order for 1N5987B_T50A through Aetrix?

Please submit a Request for Quotation (RFQ) for 1N5987B_T50A on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for 1N5987B_T50A reliable?

The price and inventory of 1N5987B_T50A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N5987B_T50A is usually 5 days.

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We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N5987B_T50A transactions.

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4.How is shipping managed for 1N5987B_T50A?

1N5987B_T50A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 1N5987B_T50A order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for 1N5987B_T50A?

For technical support, including 1N5987B_T50A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N5987B_T50A requirements.

6.How does Aetrix verify that 1N5987B_T50A is sourced from the original manufacturer or authorized distributors?

All 1N5987B_T50A products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that 1N5987B_T50A meets industry standards.

7.What is the process for return or replacement of 1N5987B_T50A?

All 1N5987B_T50A units undergo pre-shipment inspection (PSI). If there is an issue with 1N5987B_T50A, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The 1N5987B_T50A part is unused and in its original packaging.

Return procedure for 1N5987B_T50A:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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