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

onsemi 1N748A_T50A

Name: 1N748A_T50A
Brand: onsemi
SKU: 1N748A_T50A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 1N748A_T50A

Manufacturer:: onsemi

Category:: Single Zener Diodes

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

Datasheet:: 1N748A_T50A.pdf

Description:: DIODE ZENER 3.9V 500MW DO35

Quantity:: RFQ Add To RFQ list

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Inventory:2,028

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Product details

Overview

1N748A_T50A from Fairchild Semiconductor is a 3.9 V ±5% silicon Zener diode in DO-35 glass package, rated for 500 mW power dissipation at TL ≤ 75°C, with 23 Ω dynamic impedance at 20 mA and 95 mA maximum Zener current, used for precision voltage regulation and reference in low-power analog circuits.

For engineers reviewing the 1N748A_T50A datasheet, pinout, applications, or equivalent options, key selection factors include zener voltage tolerance, thermal derating behavior, cathode-band polarity marking, and DO-35 mechanical compatibility with legacy through-hole PCB layouts.

Technical Context

This device operates as a reverse-biased voltage reference diode, maintaining stable output voltage across varying load currents within its specified IZM limit. Its 3.9 V nominal zener voltage is characterized at 20 mA test current with 5% tolerance and validated over -65°C to +200°C operating temperature range.

The DO-35 glass package features axial leads with cathode band marking, supports 3/8" lead length thermal testing condition, and follows Fairchild's standardized top-marking convention: "F" logo, "48" second line, "A" third line - uniquely identifying 1N748A_T50A among the 1N746A–1N759A family.

Key Specifications

Parameter	Value and Actual Design Meaning
V_Z @ I_Z = 20 mA	3.9 V (nominal), min 3.71 V / max 4.10 V - defines regulated voltage under standard test condition
Zener Tolerance	±5% - sets absolute accuracy bound for voltage reference use
Z_Z @ 20 mA	23 Ω - determines output impedance and load regulation sensitivity
I_ZM	95 mA - maximum safe DC zener current before thermal runaway risk
P_D @ T_L ≤ 75°C	500 mW - usable power budget before 4.0 mW/°C linear derating applies
Operating Temp	-65°C to +200°C - enables deployment in automotive under-hood or industrial high-temp environments
Forward Voltage	≤1.5 V @ I_F = 200 mA - ensures predictable forward conduction if used bidirectionally

Pinout & Package

DO-35 glass axial-leaded package with cathode identified by a single color band on the body; leads are tinned copper, 3/8" length specified for thermal rating compliance.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward current entry / reverse bias return path	Connected to lower-potential node when regulating; must sink current from load
Cathode	Forward current exit / reverse bias voltage reference node	Marked with band; provides stable 3.9 V output relative to anode when reverse biased

Key Features

Feature	Design Value
±5% V_Z tolerance	Enables direct substitution in legacy 3.9 V reference designs without recalibration
DO-35 glass package	Provides hermetic sealing and long-term stability for high-reliability analog references
500 mW power rating	Supports regulation of small-signal ICs (e.g., op-amps, comparators) without external heat sinking
Cathode band polarity marking	Ensures unambiguous orientation during manual assembly and automated optical inspection

Applications

Industrial Sensor Signal Conditioning	Legacy Microcontroller Power Rail Clamping
Use Scenario: Stabilizing excitation voltage for resistive bridge sensors in PLC analog input modules. IC Role / Device Role / Timing Role: Voltage reference providing fixed 3.9 V bias to Wheatstone bridge, rejecting supply ripple. Use Value: Maintains <±0.2 V drift over -40°C to +85°C ambient due to low tempco and DO-35 thermal mass.	Use Scenario: Clamping 5 V logic rail to prevent overvoltage damage during hot-swap events in embedded controllers. IC Role / Device Role / Timing Role: Shunt regulator absorbing transient energy above 3.9 V threshold. Use Value: Limits rail excursion to ≤4.1 V (V_Z max) with 23 Ω Z_Z ensuring fast response to sub-µs spikes.
Low-Power Analog Reference Source	Automotive Body Control Module Biasing
Use Scenario: Generating stable reference for 10-bit ADC in battery-powered data loggers. IC Role / Device Role / Timing Role: Precision voltage source feeding ADC reference input (VREF+). Use Value: Delivers 3.9 V ±0.2 V accuracy with <10 µA leakage at 1 V reverse bias, minimizing quiescent current impact.	Use Scenario: Providing regulated bias to LIN transceiver interface circuitry in door module ECUs. IC Role / Device Role / Timing Role: Local 3.9 V supply reference tolerant of 12 V battery transients up to +36 V. Use Value: Survives -65°C to +150°C junction temperatures per AEC-Q101 stress profiles, validated via Fairchild qualification data.

Industrial Sensor Signal Conditioning

Legacy Microcontroller Power Rail Clamping

Use Scenario: Stabilizing excitation voltage for resistive bridge sensors in PLC analog input modules.

IC Role / Device Role / Timing Role: Voltage reference providing fixed 3.9 V bias to Wheatstone bridge, rejecting supply ripple.

Use Value: Maintains <±0.2 V drift over -40°C to +85°C ambient due to low tempco and DO-35 thermal mass.

Use Scenario: Clamping 5 V logic rail to prevent overvoltage damage during hot-swap events in embedded controllers.

IC Role / Device Role / Timing Role: Shunt regulator absorbing transient energy above 3.9 V threshold.

Use Value: Limits rail excursion to ≤4.1 V (V_Z max) with 23 Ω Z_Z ensuring fast response to sub-µs spikes.

Low-Power Analog Reference Source

Automotive Body Control Module Biasing

Use Scenario: Generating stable reference for 10-bit ADC in battery-powered data loggers.

IC Role / Device Role / Timing Role: Precision voltage source feeding ADC reference input (VREF+).

Use Value: Delivers 3.9 V ±0.2 V accuracy with <10 µA leakage at 1 V reverse bias, minimizing quiescent current impact.

Use Scenario: Providing regulated bias to LIN transceiver interface circuitry in door module ECUs.

IC Role / Device Role / Timing Role: Local 3.9 V supply reference tolerant of 12 V battery transients up to +36 V.

Use Value: Survives -65°C to +150°C junction temperatures per AEC-Q101 stress profiles, validated via Fairchild qualification data.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
1N4728A	3.3 V nominal V_Z, same DO-35 package, 500 mW rating, but 10 Ω Z_Z	Lower voltage reference; not interchangeable without circuit redesign	Select only if 3.3 V regulation is required and tighter impedance is critical
BZX55-C3V9	3.9 V nominal V_Z, ±5%, DO-35, but 500 mW rating with 90 Ω Z_Z and higher I_R	Higher leakage (10 µA @ 1 V vs. 10 µA @ 1 V for 1N748A_T50A - identical per spec sheet)	Acceptable where cost or distributor availability favors ON Semiconductor parts, but verify Z_Z impact on regulation error

Compared with 1N4728A and BZX55-C3V9, the 1N748A_T50A offers optimal balance of 3.9 V target, 23 Ω impedance, and proven thermal robustness in industrial control environments - making it preferred for new designs requiring legacy-compatible 3.9 V references.

Availability

1N748A_T50A is available at Aetrix Electronics and suitable for industrial sensor conditioning, microcontroller rail clamping, and low-power analog reference applications requiring stable component supply and long-lifecycle support.

Supply support for 1N748A_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, signal conditioning, and discrete components before its acquisition by ON Semiconductor in 2016.

The 1N748A_T50A belongs to Fairchild's legacy 1N7xxA Zener diode series, designed specifically for general-purpose voltage regulation and reference in cost-sensitive, high-volume analog systems.

FAQ

What is the exact zener voltage specification for 1N748A_T50A?

The 1N748A_T50A has a nominal zener voltage of 3.9 V, with minimum 3.71 V and maximum 4.10 V at 20 mA test current and 25°C ambient, per Fairchild Rev. D1 datasheet. This 5% tolerance is measured under thermal equilibrium at 30°C lead temperature with 3/8" lead length - the 1N748A_T50A must be mounted accordingly to meet spec.

Does 1N748A_T50A have a cathode band marking?

Yes, the 1N748A_T50A uses a single color band on the DO-35 glass body to denote the cathode terminal, consistent with JEDEC-standard axial diode marking. The band aligns with Fairchild's top-marking convention: "F" logo (line 1), "48" (line 2), "A" (line 3), confirming identity and polarity for both manual and automated assembly of the 1N748A_T50A.

What is the maximum power dissipation for 1N748A_T50A?

The 1N748A_T50A is rated for 500 mW power dissipation at lead temperature ≤ 75°C with 3/8" lead length. Above 75°C, it derates linearly at 4.0 mW/°C - meaning at 100°C lead temperature, max power drops to 400 mW. This thermal profile is defined in the Absolute Maximum Ratings table and applies directly to the 1N748A_T50A's safe operating area.

Is 1N748A_T50A suitable for automotive applications?

Yes, the 1N748A_T50A supports operating temperatures from -65°C to +200°C and is qualified per Fairchild's internal reliability standards for high-temp environments. While not AEC-Q101 certified as a standalone part, its DO-35 construction and thermal specs make it suitable for non-safety-critical automotive body electronics - confirmed by usage in legacy ECU bias networks and validated in the 1N748A_T50A datasheet.

How does the dynamic impedance of 1N748A_T50A affect regulation performance?

The 1N748A_T50A exhibits 23 Ω dynamic impedance at 20 mA, directly determining how much output voltage shifts with load current changes. For example, a 10 mA load variation causes ~230 mV output deviation - this value is critical when designing stable references for ADCs or comparators, and is a key differentiator versus alternatives like BZX55-C3V9 (90 Ω), making the 1N748A_T50A preferable for tight-regulation needs.

1N748A_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):: 3.9 V

Tolerance:: ±5%

Power - Max:: 500 mW

Impedance (Max) (Zzt):: 23 Ohms

Current - Reverse Leakage @ Vr:: 10 µA @ 1 V

Voltage - Forward (Vf) (Max) @ If:: 1.5 V @ 200 mA

Operating Temperature:: -65°C ~ 200°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: DO-35

1N748A_T50A FAQ

1.How can I place an order for 1N748A_T50A through Aetrix?

Please submit a Request for Quotation (RFQ) for 1N748A_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 1N748A_T50A reliable?

The price and inventory of 1N748A_T50A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N748A_T50A is usually 5 days.

3.What payment methods are accepted for 1N748A_T50A?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N748A_T50A transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 1N748A_T50A?

1N748A_T50A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 1N748A_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 1N748A_T50A?

For technical support, including 1N748A_T50A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N748A_T50A requirements.

6.How does Aetrix verify that 1N748A_T50A is sourced from the original manufacturer or authorized distributors?

All 1N748A_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 1N748A_T50A meets industry standards.

7.What is the process for return or replacement of 1N748A_T50A?

All 1N748A_T50A units undergo pre-shipment inspection (PSI). If there is an issue with 1N748A_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 1N748A_T50A part is unused and in its original packaging.

Return procedure for 1N748A_T50A:

1.Submit a request within 90 days.

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

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