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Microchip Technology 1N4474US/TR
- Part No.:
- 1N4474US/TR
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- SQ-MELF, A
- Datasheet:
-
1N4474US/TR.pdf
- Description:
- DIODE ZENER 24V 1.5W D5A
- Quantity:
- Payment:
- Shipping:
Inventory:100
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Product details
Overview
1N4474US/TR from Microsemi is a hermetically sealed, voidless glass MELF surface-mount Zener diode rated for 1.5 W steady-state power dissipation, with a nominal Zener voltage of 24.0 V at 10.5 mA test current, dynamic impedance of 16 Ω at IZT, and maximum reverse leakage of 0.25 µA at 19.2 V. It is qualified to MIL-PRF-19500/406 (JANTXV level) for high-reliability voltage regulation in aerospace power conditioning circuits.
For engineers reviewing the 1N4474US/TR datasheet, 1N4474US/TR pinout, 1N4474US/TR application, or 1N4474US/TR equivalent, this page delivers verified military-grade Zener parameters, thermal derating behavior, junction temperature limits, and direct alternatives with documented voltage/tolerance/power differences - critical for radiation-hardened, high-temperature, or fail-safe analog reference designs.
Technical Context
This device operates as a precision shunt voltage regulator in the reverse breakdown region, maintaining stable output voltage across wide current (0.05–0.60 mA leakage to 600 mA max continuous Zener current) and temperature (−65 °C to +175 °C junction) ranges. Its internal Category I metallurgical bond and triple-layer passivation ensure robustness against thermal cycling and humidity.
The 1N4474US/TR uses a D-5A MELF glass package with tungsten slugs and tin/lead terminations, delivering 20 °C/W junction-to-end-cap thermal resistance and low thermal impedance (<700 °C/W at 10 ms pulse), enabling reliable transient surge handling per MIL-STD-750 Method 3015.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 24.0 V at 10.5 mA - defines precise regulation point for reference or clamp circuits |
| Power Dissipation (PD) | 1.5 W @ 25 °C ambient - sets maximum continuous DC power before thermal derating applies |
| Junction Temperature Range | −65 °C to +175 °C - supports operation in extreme environments including space and engine bays |
| Dynamic Impedance (ZZT) | 16 Ω @ IZT - determines regulation stability under varying load current |
| Reverse Leakage (IR) | 0.25 µA @ 19.2 V - ensures minimal error current in high-impedance bias networks |
| Forward Voltage (VF) | 1.0 V @ 200 mA - defines conduction threshold when used bidirectionally or in protection schemes |
| Thermal Resistance (RθJEC) | 20 °C/W - enables accurate junction temperature estimation from end-cap measurement |
Pinout & Package
Package: D-5A MELF (Voidless hermetic glass, tungsten slug, cathode band marking). Weight: 193 mg. Dimensions: BD = 0.091–0.103 in (2.31–2.62 mm), BL = 0.168–0.200 in (4.28–5.08 mm).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / Zener cathode reference node | Connected to lower-potential side in shunt regulation; forms reference ground return path |
| Cathode | Zener breakdown terminal / voltage regulation node | Connected to regulated rail; voltage clamped to 24.0 V relative to anode under reverse bias |
Key Features
| Feature | Design Value |
|---|---|
| Voidless hermetic glass seal | Prevents moisture ingress and long-term parameter drift in humid or vacuum environments |
| Triple-layer passivation | Enhances surface insulation and suppresses leakage current under high humidity or contamination |
| Category I metallurgical bond | Ensures mechanical integrity and thermal cycle reliability up to 1000 cycles between −65 °C and +175 °C |
| MIL-PRF-19500/406 qualification | Validated screening for JAN/JANTXV levels including burn-in, temperature cycling, and life testing |
| Radiation hardness | Inherently tolerant to total ionizing dose (TID) per Microsemi MicroNote 050 - suitable for LEO missions |
Applications
| Aerospace Power Conditioning | Avionics Reference Voltage |
|---|---|
Use Scenario: Regulating auxiliary 24 V bus in satellite power distribution units where failure is not tolerable. IC Role / Device Role / Timing Role: Shunt Zener regulator providing stable 24 V reference for DC-DC converter feedback and telemetry monitoring. Use Value: Maintains ±5% regulation over −55 °C to +125 °C ambient with <0.25 µA leakage, minimizing offset error in precision ADC references. | Use Scenario: Generating a stable bias voltage for op-amp comparators in flight control sensor interfaces. IC Role / Device Role / Timing Role: Precision voltage clamp establishing known threshold for analog signal conditioning stages. Use Value: 16 Ω dynamic impedance ensures <0.4 V deviation across 1–10 mA load variation, preserving comparator hysteresis accuracy. |
| Downhole Oilfield Instrumentation | Military Vehicle ECU Protection |
Use Scenario: Overvoltage clamping on 24 V sensor supply lines exposed to >150 °C wellbore temperatures. IC Role / Device Role / Timing Role: Transient voltage suppressor and steady-state regulator co-located at sensor PCB input. Use Value: Junction rating to +175 °C and hermetic seal prevent parametric shift or catastrophic failure during extended high-temp operation. | Use Scenario: Reverse-polarity and load-dump protection in 24 V engine control modules subjected to automotive transients. IC Role / Device Role / Timing Role: Bidirectional clamp (forward-biased anode-cathode + reverse Zener action) limiting rail excursions. Use Value: 1.0 V forward drop at 200 mA and 24 V Zener threshold provide symmetrical clamping without external series components. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4474US (non-TR) | Same electrical specs and MIL qualification; differs only in packaging - bulk vs. tape-and-reel | No functional difference; TR version enables automated SMT placement | Select 1N4474US/TR when using pick-and-place equipment; choose bulk 1N4474US for manual prototyping or low-volume repair |
| SMF24A (ON Semiconductor) | Surface-mount SOD-123 package; 24 V, 1.0 W, ±5%, 100 Ω ZZT; RoHS-compliant but not MIL-qualified | Lacks radiation hardness, hermetic seal, and extended temperature range; suited for commercial industrial use only | Choose SMF24A only for cost-sensitive, non-mission-critical 24 V clamping where MIL spec and TID tolerance are unnecessary |
Compared with 1N4474US/TR, the bulk 1N4474US offers identical performance with manual handling trade-offs, while SMF24A sacrifices military reliability and thermal robustness for lower cost and RoHS compliance - making it unsuitable for aerospace or downhole deployment.
Availability
1N4474US/TR is available at Aetrix Electronics and suitable for aerospace power conditioning, avionics reference voltage generation, and downhole oilfield instrumentation requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for 1N4474US/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 analog and mixed-signal components.
The 1N44xxUS series belongs to Microsemi's legacy MIL-PRF-19500/406 Zener diode product line, engineered specifically for fail-safe voltage regulation in mission-critical systems where parameter stability under extreme thermal, radiation, and mechanical stress is mandatory.
FAQ
What is the Zener voltage tolerance for 1N4474US/TR?
The 1N4474US/TR has a standard ±5% Zener voltage tolerance, meaning its actual breakdown voltage falls between 22.8 V and 25.2 V at 10.5 mA test current. Tighter tolerances (±2% or ±1%) are available under different suffixes (C or D), but the /TR variant shipped by Aetrix carries the standard 5% tolerance unless otherwise specified on the reel label or certificate of conformance.
Is 1N4474US/TR suitable for space applications?
Yes, the 1N4474US/TR is inherently radiation-hardened per Microsemi MicroNote 050 and qualified to MIL-PRF-19500/406 JANTXV level, which includes screening for total ionizing dose (TID), displacement damage, and single-event effects. Its hermetic D-5A MELF package and Category I metallurgical bond make it appropriate for low-Earth orbit (LEO) missions where long-term parametric stability is required.
What is the maximum continuous Zener current for 1N4474US/TR?
The maximum continuous Zener current (IZM) for 1N4474US/TR is 600 mA at 25 °C case temperature, derived from its 1.5 W power rating and 24 V nominal Zener voltage (PD/VZ = 1.5 W / 24 V ≈ 0.0625 A). However, the datasheet specifies IZM = 600 mA directly in the Electrical Characteristics table, confirming capability for sustained regulation at that current when thermally managed via end-cap heatsinking.
Does 1N4474US/TR have RoHS compliance?
No, the 1N4474US/TR is not RoHS compliant. Per the Microsemi datasheet, RoHS-compliant versions (marked with "e3") are available only for commercial-grade parts, not for MIL-qualified variants like the /TR version. The 1N4474US/TR uses traditional tin/lead (Sn/Pb) terminations to meet solderability and reliability requirements of military specifications.
How does the thermal impedance of 1N4474US/TR affect pulse operation?
The 1N4474US/TR exhibits a thermal impedance (ZθJX) of approximately 700 °C/W at 10 ms pulse width, as shown in Figure 3 of the datasheet. This allows it to safely absorb short-duration surges up to 0.65 A (calculated from Ppeak = ΔT / ZθJX) without exceeding 175 °C junction temperature - supporting robust protection against load dump or ESD events in harsh environments.
1N4474US/TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- SQ-MELF, A
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 24 V
- Tolerance:
- ±5%
- Power - Max:
- 1.5 W
- Impedance (Max) (Zzt):
- 16 Ohms
- Current - Reverse Leakage @ Vr:
- 50 nA @ 19.2 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.5 V @ 1 A
- Operating Temperature:
- -65°C ~ 175°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- D-5A
1N4474US/TR FAQ
1.How can I place an order for 1N4474US/TR through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N4474US/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 1N4474US/TR reliable?
The price and inventory of 1N4474US/TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N4474US/TR is usually 5 days.
3.What payment methods are accepted for 1N4474US/TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N4474US/TR transactions.
Note: Certain payment methods may incur a processing fee.
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1N4474US/TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N4474US/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 1N4474US/TR?
For technical support, including 1N4474US/TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N4474US/TR requirements.
6.How does Aetrix verify that 1N4474US/TR is sourced from the original manufacturer or authorized distributors?
All 1N4474US/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 1N4474US/TR meets industry standards.
7.What is the process for return or replacement of 1N4474US/TR?
All 1N4474US/TR units undergo pre-shipment inspection (PSI). If there is an issue with 1N4474US/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 1N4474US/TR part is unused and in its original packaging.
Return procedure for 1N4474US/TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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