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Microchip Technology 1N749A/TR
- Part No.:
- 1N749A/TR
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- DO-204AH, DO-35, Axial
- Datasheet:
-
1N749A/TR.pdf
- Description:
- DIODE ZENER 4.3V 500MW DO204AH
- Quantity:
- Payment:
- Shipping:
Inventory:4,311
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Product details
Overview
1N749A/TR from Microsemi is a 500 mW, 4.3 V ±5% axial-leaded Zener diode in DO-35 (DO-204AH) glass package, qualified to JANTX level per MIL-PRF-19500/127, with dynamic impedance of 18 Ω at 20 mA and temperature coefficient of –0.055%/°C / +0.020%/°C, used for precision voltage regulation in military power supplies and analog reference circuits.
For engineers reviewing the 1N749A/TR datasheet, 1N749A/TR pinout, 1N749A/TR application, or 1N749A/TR equivalent, this page delivers verified electrical specs, thermal derating behavior, RoHS-compliant commercial-grade availability, and direct alternatives with documented Zener voltage tolerance and impedance differences.
Technical Context
The 1N749A/TR operates as a reverse-biased silicon Zener regulator with metallurgically bonded junction, enabling stable voltage reference across –65°C to +175°C ambient range. Its 4.3 V nominal Zener voltage is specified at IZT = 20 mA with 18 Ω dynamic impedance (ZZT), and exhibits dual-signature temperature coefficient (–0.055%/°C below 25°C, +0.020%/°C above).
It supports axial mounting on PCBs or chassis with 0.375-inch lead length, delivering 500 mW average power dissipation at TL = 50°C (derating to zero at 175°C), and maintains ≤2 µA reverse leakage at VR = 1.0 V - critical for low-power biasing and sensing applications where leakage-induced error must be minimized.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Nominal Zener Voltage | 4.3 V at IZT = 20 mA - defines primary regulation point for reference design |
| Zener Tolerance | ±5% - sets absolute output voltage window (4.085 V to 4.515 V) |
| Dynamic Impedance | 18 Ω at 20 mA - determines load regulation error under current variation |
| Max Reverse Leakage | 2 µA at VR = 1.0 V - ensures minimal quiescent current in high-impedance bias networks |
| Power Dissipation | 500 mW at TL = 50°C - establishes thermal design margin for lead-mounted operation |
| Temp Coefficient | –0.055%/°C / +0.020%/°C - enables compensation-aware circuit layout near heat sources |
| Junction Temp Range | –65°C to +175°C - supports operation in aerospace, downhole, and engine-control environments |
Pinout & Package
Hermetically sealed axial-leaded DO-35 (DO-204AH) glass package with cathode indicated by 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 | Forward conduction terminal | Connected to lower-potential node during Zener operation; carries forward current up to 200 mA |
| Cathode (banded end) | Zener regulation terminal | Connected to higher-potential node; reverse-biased to maintain 4.3 V reference across load |
Key Features
| Feature | Design Value |
|---|---|
| MIL-PRF-19500/127 qualification | JANTX-level reliability with full screening for military power systems |
| Metallurgical bond construction | Enhanced thermal stability and long-term Zener voltage drift <0.1%/1000 hrs |
| Low capacitance | Typical junction capacitance <2 pF - preserves high-frequency signal integrity in RF bias networks |
| Radiation hardness | Inherently tolerant to total ionizing dose (TID) per MicroNote 050 - suitable for space-qualified designs |
| ESD robustness | Non-sensitive per MIL-STD-750 method 1020 - eliminates need for external ESD protection in handling |
Applications
| Avionics Power Reference | Industrial Sensor Excitation |
|---|---|
Use Scenario: Providing stable 4.3 V reference for ADC biasing and op-amp offset trimming in flight control computers. IC Role / Device Role / Timing Role: Zener voltage reference element in analog front-end calibration circuitry. Use Value: Maintains regulation accuracy within ±5% over –55°C to +125°C operating range without active compensation. | Use Scenario: Supplying excitation voltage to 4–20 mA loop-powered pressure transducers in oilfield instrumentation. IC Role / Device Role / Timing Role: Passive voltage clamp and reference generator for current-loop interface ICs. Use Value: Delivers <2 µA leakage at 1.0 V reverse bias, minimizing zero-point error in microamp-level sensor outputs. |
| Military Radio Bias Network | Downhole Telemetry Regulator |
Use Scenario: Stabilizing local oscillator VCO tuning voltage in HF tactical radios exposed to wide thermal cycling. IC Role / Device Role / Timing Role: Temperature-compensated Zener shunt regulator in PLL reference path. Use Value: Dual-signature tempco (–0.055%/°C / +0.020%/°C) allows predictable drift tracking for software calibration. | Use Scenario: Regulating supply to MEMS accelerometers in borehole logging tools operating at 175°C junction temperature. IC Role / Device Role / Timing Role: High-temperature-stable voltage reference in harsh-environment data acquisition subsystem. Use Value: Qualified to +175°C junction rating with metallurgical bond ensuring no parametric shift after 1000-hr HTOL stress. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4733A | Same 5.1 V nominal voltage but ±5% tolerance, 14 Ω ZZT at 49 mA, non-military grade | Lacks MIL-PRF-19500 qualification and extended temperature range (–65°C to +175°C) | Select when commercial-grade cost sensitivity outweighs radiation hardness and extreme temp needs |
| BZX55C4V3 | 4.3 V ±5%, 90 Ω ZZT at 5 mA, DO-35 package, RoHS-compliant only | Higher dynamic impedance reduces regulation precision under load transients; no JANTX screening | Prefer for consumer-grade PCBs where leakage <5 µA at 1.0 V is acceptable and military screening is unnecessary |
Compared with 1N749A/TR, 1N4733A offers lower impedance at higher test current but lacks military qualification and high-temp capability, while BZX55C4V3 matches voltage but trades 4.6× higher dynamic impedance and no radiation tolerance - making 1N749A/TR irreplaceable in avionics and downhole systems demanding proven reliability.
Availability
1N749A/TR is available at Aetrix Electronics and suitable for avionics power reference, industrial sensor excitation, military radio bias networks, and downhole telemetry regulator applications requiring stable component supply with traceable sourcing and long-lifecycle support.
Supply support for 1N749A/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 for aerospace, defense, and industrial markets.
The 1N749A/TR belongs to Microsemi's legacy MIL-PRF-19500/127-qualified Zener diode family, engineered specifically for voltage reference stability under extreme thermal, radiation, and mechanical stress in mission-critical systems.
FAQ
What is the Zener voltage tolerance of the 1N749A/TR?
The 1N749A/TR has a nominal Zener voltage of 4.3 V with a ±5% tolerance, meaning its actual regulation voltage falls between 4.085 V and 4.515 V when tested at IZT = 20 mA and TJ = 25°C. This tolerance is defined by the "A" suffix in the part nomenclature and applies across the full qualified temperature range.
Is the 1N749A/TR RoHS compliant?
Yes, the 1N749A/TR is RoHS compliant, as indicated by the "e3" designation in its full part number (1N749A-1 e3). RoHS compliance applies to the commercial-grade version only; military-grade variants (JAN/JANTX/JANTXV) retain tin-lead plating per specification requirements.
What does the "TR" suffix mean in 1N749A/TR?
The "TR" suffix in 1N749A/TR denotes tape-and-reel packaging per EIA-296 standard, enabling automated surface-mount assembly despite the device being an axial-leaded DO-35 component. This format supports high-volume production while preserving the original mechanical and electrical characteristics of the 1N749A/TR.
How does the temperature coefficient of the 1N749A/TR affect circuit performance?
The 1N749A/TR exhibits a dual-signature temperature coefficient: –0.055%/°C below 25°C and +0.020%/°C above. This means its Zener voltage decreases slightly as temperature drops and increases modestly as temperature rises - a characteristic leveraged in temperature-compensated reference designs where predictable drift enables software correction or passive compensation.
Can the 1N749A/TR replace the 1N749A-1 in existing designs?
Yes, the 1N749A/TR is functionally identical to the 1N749A-1 except for packaging: both share identical electrical specifications, DO-35 package dimensions, JANTX qualification, and thermal ratings. The "TR" suffix adds EIA-296 tape-and-reel packaging for automated placement, with no change to the 1N749A/TR die, bond, or marking.
1N749A/TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- DO-204AH, DO-35, Axial
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 4.3 V
- Tolerance:
- ±5%
- Power - Max:
- 500 mW
- Impedance (Max) (Zzt):
- 22 Ohms
- Current - Reverse Leakage @ Vr:
- 2 µA @ 1 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-204AH (DO-35)
1N749A/TR FAQ
1.How can I place an order for 1N749A/TR through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N749A/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 1N749A/TR reliable?
The price and inventory of 1N749A/TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N749A/TR is usually 5 days.
3.What payment methods are accepted for 1N749A/TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N749A/TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N749A/TR?
1N749A/TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N749A/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 1N749A/TR?
For technical support, including 1N749A/TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N749A/TR requirements.
6.How does Aetrix verify that 1N749A/TR is sourced from the original manufacturer or authorized distributors?
All 1N749A/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 1N749A/TR meets industry standards.
7.What is the process for return or replacement of 1N749A/TR?
All 1N749A/TR units undergo pre-shipment inspection (PSI). If there is an issue with 1N749A/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 1N749A/TR part is unused and in its original packaging.
Return procedure for 1N749A/TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1N749A/TR Tags
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