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

Microchip Technology 1N748A/TR

Name: 1N748A/TR
Brand: Microchip Technology
SKU: 1N748A/TR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 1N748A/TR

Manufacturer:: Microchip Technology

Category:: Single Zener Diodes

Package:: DO-204AA, DO-7, Axial

Datasheet:: 1N748A/TR.pdf

Description:: DIODE ZENER 3.9V 500MW DO7

Quantity:: RFQ Add To RFQ list

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Inventory:5,926

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Product details

Overview

1N748A/TR from Microsemi is a 500 mW, 3.9 V ±5% Zener diode in DO-35 glass axial package, qualified to JANTX level per MIL-PRF-19500/127, with 20 Ω dynamic impedance at 30 mA and -0.060 %/°C temperature coefficient - used for precision voltage reference and regulation in military power supply monitoring circuits.

For engineers reviewing the 1N748A/TR datasheet, 1N748A/TR pinout, 1N748A/TR application, or 1N748A/TR equivalent, key selection criteria include Zener voltage tolerance, thermal resistance (250 °C/W junction-to-lead), reverse leakage (≤2 µA at 1.0 V), maximum Zener current (100 mA), and RoHS compliance status of the TR-suffixed commercial variant.

Technical Context

This discrete Zener diode operates in reverse breakdown to maintain stable voltage across load variations and temperature shifts from –65 °C to +175 °C. Its metallurgically bonded junction ensures long-term stability under thermal cycling and radiation exposure per MicroNote 050.

Designed for fixed-voltage regulation in low-power analog circuits, it delivers 3.9 V nominal output at I_ZT = 30 mA with ZZT = 20 Ω and α_VZ = –0.060 %/°C - enabling predictable drift compensation in reference designs without active feedback.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage V_Z	3.9 V ±5% at I_ZT = 30 mA - defines regulated output voltage with bounded error for calibration-critical references.
Power Dissipation	500 mW at T_L = 50 °C (derates linearly to zero at 175 °C) - sets maximum continuous DC power handling on lead-mounted PCBs.
Dynamic Impedance ZZT	20 Ω at I_ZT = 30 mA - determines output voltage variation under load current changes; lower value improves regulation fidelity.
Reverse Leakage IR	≤2 µA at V_R = 1.0 V - ensures minimal parasitic current draw when below breakdown, critical for battery-powered standby circuits.
Temp. Coefficient α_VZ	–0.060 %/°C - quantifies voltage drift per degree Celsius; negative sign indicates decreasing V_Z with rising temperature.
Junction-to-Lead R_θJL	250 °C/W - governs thermal rise from junction to lead; used with derating curves to calculate safe operating current at elevated ambient temps.
Forward Voltage V_F	1.1 V at I_F = 200 mA - specifies conduction loss when used in forward-biased protection or clamping roles.

Pinout & Package

DO-35 (DO-204AH) hermetically sealed glass axial package with cathode indicated by color band; leads are tin-lead or RoHS-compliant matte tin plated, solderable per MIL-STD-750 method 2026.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Non-banded end	Connected to circuit ground or lower potential node during Zener operation; carries full reverse current in regulation mode.
Cathode	Banded end	Connected to regulated voltage rail; polarity marking is mandatory for correct orientation in series-shunt regulation topologies.

Key Features

Feature	Design Value
MIL-PRF-19500/127 qualification	JANTX-level screening ensures reliability for aerospace and defense systems requiring extended temperature operation and radiation hardness.
Metallurgical bond construction	Eliminates wire-bond fatigue failure mechanisms, improving long-term stability under thermal shock and mechanical vibration.
Low capacitance	Minimizes high-frequency coupling in RF-adjacent bias networks and fast-switching power supply feedback paths.
ESD robustness	Non-sensitive to ESD per MIL-STD-750 method 1020 - reduces handling sensitivity during manual assembly and field repair.

Applications

Power Supply Reference	Military Sensor Biasing
Use Scenario: Stable 3.9 V reference for op-amp comparators and ADC voltage dividers in unregulated DC-DC converter outputs. IC Role / Device Role / Timing Role: Passive voltage reference element providing fixed threshold against which system voltages are monitored. Use Value: Enables ±5% accuracy over –65 °C to +175 °C without trimming, reducing calibration overhead in field-deployed equipment.	Use Scenario: Biasing photodiode amplifiers and MEMS transducer signal chains in ruggedized environmental sensors. IC Role / Device Role / Timing Role: Low-noise, low-capacitance Zener shunt regulator establishing clean analog supply rails. Use Value: Maintains <2 µA leakage at 1.0 V reverse bias, preserving microamp-level sensor quiescent current budgets.
Overvoltage Clamp	Temperature-Stable Oscillator Bias
Use Scenario: Protecting microcontroller I/O pins from transient surges in industrial control inputs. IC Role / Device Role / Timing Role: Reverse-biased clamping device limiting voltage excursions above 3.9 V. Use Value: Responds within nanoseconds to transients while sustaining 100 mA peak Zener current per pulse rating.	Use Scenario: Setting bias point for crystal oscillator amplifier stages where drift must remain below ±0.1% over temperature. IC Role / Device Role / Timing Role: Temperature-compensated voltage reference defining amplifier DC operating point. Use Value: –0.060 %/°C coefficient enables predictable offset correction in oven-controlled oscillator (OCXO) support circuitry.

Power Supply Reference

Military Sensor Biasing

Use Scenario: Stable 3.9 V reference for op-amp comparators and ADC voltage dividers in unregulated DC-DC converter outputs.

IC Role / Device Role / Timing Role: Passive voltage reference element providing fixed threshold against which system voltages are monitored.

Use Value: Enables ±5% accuracy over –65 °C to +175 °C without trimming, reducing calibration overhead in field-deployed equipment.

Use Scenario: Biasing photodiode amplifiers and MEMS transducer signal chains in ruggedized environmental sensors.

IC Role / Device Role / Timing Role: Low-noise, low-capacitance Zener shunt regulator establishing clean analog supply rails.

Use Value: Maintains <2 µA leakage at 1.0 V reverse bias, preserving microamp-level sensor quiescent current budgets.

Overvoltage Clamp

Temperature-Stable Oscillator Bias

Use Scenario: Protecting microcontroller I/O pins from transient surges in industrial control inputs.

IC Role / Device Role / Timing Role: Reverse-biased clamping device limiting voltage excursions above 3.9 V.

Use Value: Responds within nanoseconds to transients while sustaining 100 mA peak Zener current per pulse rating.

Use Scenario: Setting bias point for crystal oscillator amplifier stages where drift must remain below ±0.1% over temperature.

IC Role / Device Role / Timing Role: Temperature-compensated voltage reference defining amplifier DC operating point.

Use Value: –0.060 %/°C coefficient enables predictable offset correction in oven-controlled oscillator (OCXO) support circuitry.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
1N748A-1	No "TR" suffix; non-tape-and-reel, bulk packaging; identical electrical specs and JANTX qualification.	Preferred for prototype builds or low-volume hand-soldered assemblies where reel feeding is unnecessary.	Select 1N748A-1 when tape-and-reel automation is not required and MIL-spec traceability remains essential.
BZX55C3V9	Commercial-grade, ±5% tolerance, 500 mW, DO-35, but not MIL-qualified; higher typical leakage (≤5 µA).	Suitable for cost-sensitive industrial controls where military screening is not mandated.	Choose BZX55C3V9 only for non-military applications accepting reduced reliability screening and wider process variation.

Compared with 1N748A/TR, the 1N748A-1 offers identical performance in bulk form but lacks automated placement compatibility, while BZX55C3V9 trades MIL qualification and tighter leakage for lower unit cost in commercial designs.

Availability

1N748A/TR is available at Aetrix Electronics and suitable for military avionics power monitoring, ruggedized sensor biasing, and industrial overvoltage protection requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for 1N748A/TR 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

Microsemi Corporation (now part of Microchip Technology) is a U.S.-based semiconductor company specializing in high-reliability, radiation-hardened, and military-qualified components.

The 1N748A/TR belongs to Microsemi's legacy MIL-PRF-19500/127 qualified Zener diode family, engineered for voltage regulation in mission-critical analog subsystems where long-term parametric stability and extreme environmental resilience are mandatory.

FAQ

What is the Zener voltage tolerance of the 1N748A/TR?

The 1N748A/TR has a nominal Zener voltage of 3.9 V with a ±5% tolerance, as indicated by the "A" suffix in its nomenclature per JEDEC standards. This means the actual measured V_Z at I_ZT = 30 mA falls between 3.705 V and 4.095 V at 25 °C. The tolerance remains valid across the full operating temperature range of –65 °C to +175 °C, though voltage drift follows the specified –0.060 %/°C coefficient.

Is the 1N748A/TR RoHS compliant?

Yes, the 1N748A/TR is RoHS compliant, as confirmed by the "e3" designation in its full part number and documentation in Microsemi's T4-LDS-0288 datasheet. RoHS compliance applies to the commercial-grade version only; the TR suffix denotes tape-and-reel packaging, and the e3 marking confirms annealed matte-tin plating meeting EU Directive 2011/65/EU requirements.

What does the "TR" suffix mean in 1N748A/TR?

The "TR" suffix in 1N748A/TR indicates tape-and-reel packaging per EIA-296 standard, enabling automated surface-mount or axial-leaded placement in high-volume manufacturing. It does not alter electrical specifications - the 1N748A/TR retains identical Zener voltage, power rating, and MIL-PRF-19500/127 JANTX qualification as the bulk 1N748A-1 variant.

What is the maximum Zener current rating for the 1N748A/TR?

The 1N748A/TR has a maximum Zener current (I_ZM) of 100 mA, derived from its 500 mW power rating and 3.9 V nominal Zener voltage (P = V × I). This rating assumes operation at T_L = 50 °C with 0.375 inch lead length; current must be derated linearly to zero at 175 °C per Figure 1 in the datasheet.

How is polarity marked on the 1N748A/TR?

The 1N748A/TR uses a cathode band - a single colored ring near one end of the DO-35 glass body - to indicate the cathode terminal. During Zener regulation, the banded end must be held at a higher potential than the anode (non-banded end). This marking is consistent across all devices in the 1N746A–1N759A series and is verified per MIL-STD-750 method 2026.

1N748A/TR Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

Package/Case:: DO-204AA, DO-7, Axial

Packaging:: Tape & Reel (TR)

Product Status:: Active

Voltage - Zener (Nom) (Vz):: 3.9 V

Tolerance:: ±5%

Power - Max:: 500 mW

Impedance (Max) (Zzt):: 23 Ohms

Current - Reverse Leakage @ Vr:: 2 µA @ 10 V

Voltage - Forward (Vf) (Max) @ If:: 1.1 V @ 200 mA

Operating Temperature:: -65°C ~ 175°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: DO-7 (DO-204AA)

1N748A/TR FAQ

1.How can I place an order for 1N748A/TR through Aetrix?

Please submit a Request for Quotation (RFQ) for 1N748A/TR 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/TR reliable?

The price and inventory of 1N748A/TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N748A/TR is usually 5 days.

3.What payment methods are accepted for 1N748A/TR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N748A/TR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 1N748A/TR?

1N748A/TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 1N748A/TR 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/TR?

For technical support, including 1N748A/TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N748A/TR requirements.

6.How does Aetrix verify that 1N748A/TR is sourced from the original manufacturer or authorized distributors?

All 1N748A/TR 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/TR meets industry standards.

7.What is the process for return or replacement of 1N748A/TR?

All 1N748A/TR units undergo pre-shipment inspection (PSI). If there is an issue with 1N748A/TR, 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/TR part is unused and in its original packaging.

Return procedure for 1N748A/TR:

1.Submit a request within 90 days.

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

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