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Microchip Technology 1N749A-1/TR
- Part No.:
- 1N749A-1/TR
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- DO-204AH, DO-35, Axial
- Datasheet:
-
1N749A-1/TR.pdf
- Description:
- DIODE ZENER 4.3V 500MW DO204AH
- Quantity:
- Payment:
- Shipping:
Inventory:4,919
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Product details
Overview
1N749A-1/TR from Microsemi is a 500 mW, 4.3 V ±5% axial-leaded silicon 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 to +0.020%/°C, used for precision voltage regulation in military-grade power supply references.
For engineers reviewing the 1N749A-1/TR datasheet, 1N749A-1/TR pinout, 1N749A-1/TR application, or 1N749A-1/TR equivalent, key selection criteria include Zener voltage tolerance, junction-to-lead thermal resistance (250 °C/W), reverse leakage (≤2 µA at 1.0 V), maximum Zener current (50 mA), and RoHS-compliant tape-and-reel packaging (TR suffix).
Technical Context
The 1N749A-1/TR operates as a two-terminal voltage reference device in reverse-bias breakdown mode, with nominal Zener voltage of 4.3 V measured at IZT = 20 mA. Its metallurgically bonded junction ensures stable regulation across –65 °C to +175 °C operating temperature range.
It exhibits low dynamic impedance (18 Ω) and minimal capacitance, enabling stable regulation under varying load and temperature conditions. The cathode band marking defines polarity, requiring the banded end to be held positive relative to the anode during regulation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage VZ | 4.3 V ±5% at IZT = 20 mA - defines precise regulation point for reference circuits |
| Power Dissipation | 500 mW at TL = 50 °C - supports continuous operation in compact leaded layouts with 0.375″ lead length |
| Dynamic Impedance ZZT | 18 Ω at 20 mA - ensures low output impedance for stable voltage under load transients |
| Reverse Leakage IR | ≤2 µA at VR = 1.0 V - minimizes quiescent current in low-power bias networks |
| Temp Coefficient αVZ | –0.055%/°C to +0.020%/°C - enables predictable drift compensation in wide-temperature designs |
| Junction-to-Lead RθJL | 250 °C/W - determines thermal rise under sustained DC load, critical for reliability derating |
| Max Zener Current IZM | 50 mA - sets upper limit for safe DC regulation without exceeding 500 mW at 4.3 V |
Pinout & Package
Hermetically sealed axial-leaded DO-35 (DO-204AH) glass package with cathode indicated by a single 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 | Reference ground node | Connected to circuit common; reverse-biased operation requires cathode > anode |
| Cathode | Regulated output node | Banded end; held at stable 4.3 V above anode when reverse current ≥ IZK |
Key Features
| Feature | Design Value |
|---|---|
| MIL-PRF-19500/127 qualification | JANTX-level screening ensures reliability for aerospace and defense power reference applications |
| Metallurgical bond construction | Eliminates interfacial delamination risk under thermal cycling and high-reliability stress |
| Low capacitance | Enables use in high-frequency bias networks without signal coupling or instability |
| ESD robustness | Non-sensitive per MIL-STD-750 method 1020 - simplifies handling in production environments |
| Radiation hardness | Inherently radiation-tolerant per Microsemi MicroNote 050 - suitable for space-qualified systems |
Applications
| Power Supply Reference | Overvoltage Clamp |
|---|---|
Use Scenario: Stable 4.3 V reference for linear regulator feedback or ADC reference divider. IC Role / Device Role / Timing Role: Two-terminal shunt voltage reference providing fixed bias point. Use Value: ±5% initial tolerance and low ZZT ensure <±10 mV regulation error over 1–50 mA load range. | Use Scenario: Protection of 3.3 V logic inputs against transient surges beyond 5 V. IC Role / Device Role / Timing Role: Reverse-biased clamping element diverting excess energy to ground. Use Value: Fast turn-on at 4.3 V with ≤2 µA leakage below clamp threshold preserves signal integrity. |
| Temperature-Stable Bias Network | Military-Grade Sensor Excitation |
Use Scenario: Biasing op-amp input stages in instrumentation amplifiers operating from –55 °C to +125 °C. IC Role / Device Role / Timing Role: Precision DC voltage source compensating for amplifier offset drift. Use Value: Dual-signature tempco (–0.055%/°C to +0.020%/°C) allows predictable drift modeling and trimming. | Use Scenario: Exciting bridge-based pressure sensors in avionics environmental control units. IC Role / Device Role / Timing Role: Regulated excitation source meeting MIL-STD-810 shock/vibe and extended temperature requirements. Use Value: JANTX qualification and hermetic DO-35 package ensure long-term stability in high-reliability field deployments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4733A | Same 5.1 V nominal rating but ±5% tolerance, 1 W power, DO-41 package - higher power, larger footprint | Used in commercial power supplies where size and military qualification are not required | Select 1N4733A only if 1 W dissipation and PCB-mount DO-41 compatibility are needed |
| BZX55-C4V3 | 4.3 V ±5%, 500 mW, DO-35, but commercial-grade only - no MIL-PRF-19500 qualification or JANTX screening | Targeted at cost-sensitive industrial controls with standard temperature range (–55 °C to +150 °C) | Choose BZX55-C4V3 when RoHS compliance and lower cost outweigh military reliability requirements |
Compared with 1N4733A and BZX55-C4V3, the 1N749A-1/TR uniquely delivers JANTX-level screening, hermetic DO-35 packaging, and dual-signature temperature coefficient - making it irreplaceable in mission-critical analog references where long-term parametric stability and radiation tolerance are mandatory.
Availability
1N749A-1/TR is available at Aetrix Electronics and suitable for aerospace power references, defense system voltage clamps, and industrial sensor excitation circuits requiring stable component supply across extended temperature and lifecycle demands.
Supply support for 1N749A-1/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) designs high-reliability analog and mixed-signal semiconductors for aerospace, defense, and industrial markets.
The 1N749A-1/TR belongs to Microsemi's legacy MIL-PRF-19500-qualified Zener diode family, engineered specifically for precision voltage regulation in harsh-environment electronic systems.
FAQ
What is the Zener voltage tolerance of the 1N749A-1/TR?
The 1N749A-1/TR has a nominal Zener voltage of 4.3 V with a ±5% tolerance, as indicated by the "A" suffix in its nomenclature per JEDEC standards. This means the actual VZ at IZT = 20 mA falls between 4.085 V and 4.515 V at 25 °C. The tolerance remains valid across the full operating temperature range of –65 °C to +175 °C, supported by JANTX-level qualification testing.
Is the 1N749A-1/TR RoHS compliant?
Yes, the 1N749A-1/TR is RoHS compliant, as confirmed by the "e3" designation in its full part number variant and documented in Microsemi's T4-LDS-0288 specification. RoHS compliance applies to the commercial-grade version only; the JANTX-qualified unit retains tin-lead plating per MIL-STD-750, but the TR tape-and-reel packaging option meets RoHS requirements for assembly processes.
What does the "TR" suffix mean in 1N749A-1/TR?
The "TR" suffix in 1N749A-1/TR indicates tape-and-reel packaging per EIA-296 standard, enabling automated surface-mount or axial insertion assembly. This format contains the DO-35 devices in carrier tape with cover tape, optimized for pick-and-place equipment. The "TR" does not alter electrical specifications - all parameters including VZ = 4.3 V, ZZT = 18 Ω, and JANTX qualification remain identical to the bulk version.
How is polarity marked on the 1N749A-1/TR?
The 1N749A-1/TR uses a single cathode band painted on the glass body to indicate polarity. During Zener regulation, the banded end must be held positive relative to the unmarked (anode) end. This marking is consistent across all DO-35 Zeners in the 1N746A–1N759A series and is verified per MIL-STD-750 method 2015 for legibility and permanence.
What is the maximum Zener current for continuous operation of the 1N749A-1/TR?
The maximum Zener current (IZM) for continuous DC operation of the 1N749A-1/TR is 50 mA, derived from its 500 mW power rating and 4.3 V nominal Zener voltage (P = V × I → I = 0.5 W / 4.3 V ≈ 116 mA, derated to 50 mA to accommodate impedance heating and thermal equilibrium). This value is specified in the Electrical Characteristics table on page 3 of T4-LDS-0288 Rev. 1.
1N749A-1/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):
- 18 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-1/TR FAQ
1.How can I place an order for 1N749A-1/TR through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N749A-1/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-1/TR reliable?
The price and inventory of 1N749A-1/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-1/TR is usually 5 days.
3.What payment methods are accepted for 1N749A-1/TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N749A-1/TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N749A-1/TR?
1N749A-1/TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N749A-1/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-1/TR?
For technical support, including 1N749A-1/TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N749A-1/TR requirements.
6.How does Aetrix verify that 1N749A-1/TR is sourced from the original manufacturer or authorized distributors?
All 1N749A-1/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-1/TR meets industry standards.
7.What is the process for return or replacement of 1N749A-1/TR?
All 1N749A-1/TR units undergo pre-shipment inspection (PSI). If there is an issue with 1N749A-1/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-1/TR part is unused and in its original packaging.
Return procedure for 1N749A-1/TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1N749A-1/TR Tags
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