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

Microchip Technology 1N4746P/TR8

Name: 1N4746P/TR8
Brand: Microchip Technology
SKU: 1N4746P/TR8
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 1N4746P/TR8

Manufacturer:: Microchip Technology

Category:: Single Zener Diodes

Package:: DO-204AL, DO-41, Axial

Datasheet:: 1N4746P/TR8.pdf

Description:: DIODE ZENER 18V 1W DO204AL

Quantity:: RFQ Add To RFQ list

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Inventory:5,594

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Product details

Overview

1N4746P/TR8 from Microsemi is a 1 W, 18 V ±5% Zener diode in DO-41 plastic package, designed for precision voltage regulation in power supply feedback loops, reference circuits, and overvoltage protection. It delivers stable regulation at 14 mA test current with 20 Ω dynamic impedance, operates from –65°C to +150°C, and features moisture sensitivity level 1 with no dry pack required.

For engineers reviewing the 1N4746P/TR8 datasheet, 1N4746P/TR8 pinout, 1N4746P/TR8 application, or 1N4746P/TR8 equivalent, key selection criteria include its 18 V nominal Zener voltage, 1 W power rating at 25°C, 20 Ω Zener impedance at 14 mA, thermal resistance of 45°C/W (junction-to-lead), and RoHS-compliant "e3" variant availability.

Technical Context

This discrete Zener diode functions as a two-terminal shunt voltage regulator, maintaining a stable 18 V output across a wide operating current range (1 mA to 250 mA) and temperature span (–65°C to +150°C). Its breakdown behavior is characterized by a sharp knee at I_ZK = 0.25 mA and Z_ZK = 500 Ω, ensuring reliable turn-on in low-current biasing applications.

The device uses silicon PN-junction technology with void-free thermosetting epoxy encapsulation (UL94V-0), tin-lead or matte-tin plating, and cathode polarity marked by a band. It is rated for 260°C soldering (10 s max) and exhibits negligible ESD sensitivity per MIL-STD-750 Method 1020.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	18 V ±5% at I_ZT = 14 mA - defines regulated output voltage tolerance under standard test conditions
Power Dissipation	1.0 W at T_L ≤ 105°C (3/8″ lead length) - sets maximum continuous power handling before thermal derating
Dynamic Impedance (Z_ZT)	20 Ω at I_ZT = 14 mA - determines output voltage variation under load current changes
Reverse Leakage Current	5 μA max at V_R = 13.7 V - ensures minimal quiescent current in standby regulation mode
Thermal Resistance	45 °C/W junction-to-lead - enables accurate junction temperature estimation for reliability analysis
Operating Temperature	–65°C to +150°C - supports deployment in industrial, automotive, and aerospace environments
Forward Voltage	1.2 V max at I_F = 200 mA - relevant for reverse-biased protection or forward-conduction fault scenarios

Pinout & Package

Package: DO-41 (DO-204AL) axial-leaded plastic case, 0.7 g weight, UL94V-0 compliant epoxy body, cathode indicated by color band.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Current sink during Zener conduction	Connected to lower-potential node (e.g., ground or return path) when regulating
Cathode	Current source during Zener conduction	Banded end; connected to higher-potential node (e.g., supply rail or feedback point)

Key Features

Feature	Design Value
JEDEC-registered 1N47xxAP series	Ensures cross-manufacturer compatibility and standardized electrical/mechanical specs
5% Zener voltage tolerance (A suffix)	Guarantees output stability within ±0.9 V of 18 V under production conditions
Moisture Sensitivity Level 1	Eliminates dry-pack requirement and floor-life constraints for SMT assembly
RoHS-compliant "e3" variant option	Enables compliance with environmental directives without performance trade-offs
Nonsensitive to ESD (MIL-STD-750 Method 1020)	Reduces handling precautions and eliminates need for ESD-protected workstations

Applications

Power Supply Feedback Regulation	Overvoltage Clamp Protection
Use Scenario: Stabilizing output voltage in linear regulators or switching converter feedback networks. IC Role / Device Role / Timing Role: Shunt reference element providing precise 18 V reference for error amplifier input. Use Value: Maintains ±5% output accuracy over –40°C to +85°C ambient with <20 Ω dynamic impedance limiting load-induced drift.	Use Scenario: Protecting downstream ICs from transient voltage spikes on 24 V rails. IC Role / Device Role / Timing Role: Clamping device that conducts above 18 V to divert surge energy to ground. Use Value: Limits peak voltage to ≤18.9 V (5% tolerance) with 250 mA max surge current capability per pulse.
Reference Voltage Source	Signal-Level Voltage Translation
Use Scenario: Generating stable bias points for op-amp comparators or ADC references. IC Role / Device Role / Timing Role: Low-noise, low-drift DC reference node in analog signal chains. Use Value: Delivers 18 V reference with <5 μA leakage at 13.7 V, minimizing loading on high-impedance sources.	Use Scenario: Level-shifting logic signals between 3.3 V and 18 V domains in industrial I/O modules. IC Role / Device Role / Timing Role: Bidirectional clamping diode defining upper voltage rail for open-collector interfaces. Use Value: Provides robust 18 V clamping with 1.2 V forward drop, enabling safe interface coupling without external resistors.

Power Supply Feedback Regulation

Overvoltage Clamp Protection

Use Scenario: Stabilizing output voltage in linear regulators or switching converter feedback networks.

IC Role / Device Role / Timing Role: Shunt reference element providing precise 18 V reference for error amplifier input.

Use Value: Maintains ±5% output accuracy over –40°C to +85°C ambient with <20 Ω dynamic impedance limiting load-induced drift.

Use Scenario: Protecting downstream ICs from transient voltage spikes on 24 V rails.

IC Role / Device Role / Timing Role: Clamping device that conducts above 18 V to divert surge energy to ground.

Use Value: Limits peak voltage to ≤18.9 V (5% tolerance) with 250 mA max surge current capability per pulse.

Reference Voltage Source

Signal-Level Voltage Translation

Use Scenario: Generating stable bias points for op-amp comparators or ADC references.

IC Role / Device Role / Timing Role: Low-noise, low-drift DC reference node in analog signal chains.

Use Value: Delivers 18 V reference with <5 μA leakage at 13.7 V, minimizing loading on high-impedance sources.

Use Scenario: Level-shifting logic signals between 3.3 V and 18 V domains in industrial I/O modules.

IC Role / Device Role / Timing Role: Bidirectional clamping diode defining upper voltage rail for open-collector interfaces.

Use Value: Provides robust 18 V clamping with 1.2 V forward drop, enabling safe interface coupling without external resistors.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
1N4746A	No "P" suffix: glass-body DO-35 package; higher thermal resistance (70°C/W vs. 45°C/W)	Less suitable for high-power-density PCB layouts due to inferior heat dissipation	Select 1N4746P/TR8 when board space or thermal management limits require plastic DO-41 construction
MMSZ4708T1G	Surface-mount SOD-123 package; 18 V, 500 mW rating; 30 Ω Z_ZT at 5 mA	Lower power handling and different test current - not interchangeable in 1 W designs	Choose MMSZ4708T1G only for space-constrained, low-power (<500 mW) applications requiring SMT assembly

Compared with 1N4746A and MMSZ4708T1G, the 1N4746P/TR8 offers superior thermal performance in through-hole layouts and full 1 W power capability at elevated temperatures - critical for industrial power supplies where sustained regulation under load is required.

Availability

1N4746P/TR8 is available at Aetrix Electronics and suitable for industrial power supplies, analog reference circuits, and overvoltage protection systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for 1N4746P/TR8 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 (now part of Microchip Technology) is a U.S.-based semiconductor company specializing in high-reliability analog, mixed-signal, and RF solutions for aerospace, defense, and industrial markets.

The 1N4746P/TR8 belongs to Microsemi's legacy 1N47xxAP Zener diode family, engineered for ruggedized voltage regulation in harsh-environment power systems where thermal stability, long-term parametric consistency, and JEDEC-standard compliance are essential.

FAQ

What is the Zener voltage tolerance of the 1N4746P/TR8?

The 1N4746P/TR8 has a nominal Zener voltage of 18 V with a ±5% tolerance, as indicated by the "A" suffix in its part number. This means the actual measured V_Z falls between 17.1 V and 18.9 V when tested at 14 mA and 25°C lead temperature. The tolerance is guaranteed across the full operating temperature range and applies to all units in production lots.

Can the 1N4746P/TR8 be used in surface-mount designs?

No - the 1N4746P/TR8 uses a DO-41 axial-leaded package and is intended for through-hole mounting. For surface-mount equivalents, Microsemi offers the SMAJ4746A (SMA package) and MLL4746A (SOD-123 variant); however, these differ in power rating, thermal performance, and footprint. The 1N4746P/TR8 itself requires axial insertion and wave or hand soldering.

What is the maximum surge current rating for the 1N4746P/TR8?

The 1N4746P/TR8 has a maximum non-repetitive reverse surge current (I_SM) of 250 mA, measured using a ½ sine-wave pulse of 1/120 second duration at 25°C ambient. This rating supports transient overvoltage clamping in power rails but does not imply continuous operation at this current - sustained regulation must remain within the 1 W DC power limit.

Does the 1N4746P/TR8 require dry packing for moisture sensitivity?

No - the 1N4746P/TR8 is classified as Moisture Sensitivity Level 1 per IPC/JEDEC J-STD-020B, meaning it has unlimited floor life and does not require dry pack or baking prior to soldering. This simplifies manufacturing logistics and eliminates moisture-related popcorning risks during reflow or wave soldering.

How does the thermal resistance of the 1N4746P/TR8 compare to glass-body variants?

The 1N4746P/TR8 has a junction-to-lead thermal resistance of 45°C/W at 3/8″ (10 mm) lead length, significantly lower than the 70°C/W typical of glass-body 1N4746A (DO-35). This 36% improvement enables higher sustained power delivery in thermally constrained layouts and reduces junction temperature rise under identical load conditions.

1N4746P/TR8 Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

Package/Case:: DO-204AL, DO-41, Axial

Packaging:: Tape & Reel (TR)

Product Status:: Active

Voltage - Zener (Nom) (Vz):: 18 V

Tolerance:: ±10%

Power - Max:: 1 W

Impedance (Max) (Zzt):: 20 Ohms

Current - Reverse Leakage @ Vr:: 5 µA @ 13.7 V

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

Operating Temperature:: -65°C ~ 150°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: DO-204AL (DO-41)

1N4746P/TR8 FAQ

1.How can I place an order for 1N4746P/TR8 through Aetrix?

Please submit a Request for Quotation (RFQ) for 1N4746P/TR8 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 1N4746P/TR8 reliable?

The price and inventory of 1N4746P/TR8 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N4746P/TR8 is usually 5 days.

3.What payment methods are accepted for 1N4746P/TR8?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N4746P/TR8 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 1N4746P/TR8?

1N4746P/TR8 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 1N4746P/TR8 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 1N4746P/TR8?

For technical support, including 1N4746P/TR8 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N4746P/TR8 requirements.

6.How does Aetrix verify that 1N4746P/TR8 is sourced from the original manufacturer or authorized distributors?

All 1N4746P/TR8 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 1N4746P/TR8 meets industry standards.

7.What is the process for return or replacement of 1N4746P/TR8?

All 1N4746P/TR8 units undergo pre-shipment inspection (PSI). If there is an issue with 1N4746P/TR8, 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 1N4746P/TR8 part is unused and in its original packaging.

Return procedure for 1N4746P/TR8:

1.Submit a request within 90 days.

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

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