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Microchip Technology 1N6491US
- Part No.:
- 1N6491US
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- SQ-MELF, A
- Datasheet:
-
1N6491US.pdf
- Description:
- DIODE ZENER 5.6V 1.5W SQ-MELF
- Quantity:
- Payment:
- Shipping:
Inventory:5,150
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Product details
Overview
1N6491US from Microsemi is a hermetically sealed, voidless glass MELF (D-5A) surface-mount Zener diode rated for 1.5 W steady-state power dissipation, with nominal Zener voltage of 5.6 V at 45 mA test current, dynamic impedance of 5 Ω at IZT, and maximum reverse leakage of 1.0 µA at 4.7 V. It is qualified to MIL-PRF-19500/406 at JANTXV level and used in precision voltage regulation within radiation-hardened military avionics power supplies.
For engineers reviewing the 1N6491US datasheet, 1N6491US pinout, 1N6491US application, or 1N6491US equivalent, key selection criteria include its 5.6 V Zener voltage tolerance (±5%), Category III internal metallurgical bond, -65°C to +175°C junction temperature range, and thermal resistance of 20°C/W junction-to-end-cap - critical for high-reliability thermal management in sealed aerospace modules.
Technical Context
The 1N6491US operates as a precision shunt voltage regulator in the reverse breakdown region, with Zener voltage specified at IZT = 45 mA and knee current IZK = 0.5 mA. Its low dynamic impedance (5 Ω) ensures stable regulation under varying load currents, while its Category III metallurgical bond supports high mechanical robustness and long-term reliability under thermal cycling.
Designed for end-cap mounted thermal conduction, it uses a tungsten slug within voidless hard glass construction and achieves 20°C/W junction-to-end-cap thermal resistance. The device exhibits <0.25 µA reverse leakage at VR = 4.7 V and maintains regulation across -65°C to +175°C, meeting MIL-PRF-19500/406 requirements for JANTXV-grade applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 5.6 V at 45 mA - defines precise regulation point for reference and clamp circuits |
| Power Dissipation (PD) | 1.5 W at 25°C case - sets maximum continuous DC power handling before thermal derating |
| Dynamic Impedance (ZZT) | 5 Ω at IZT - determines output voltage variation under load transients |
| Junction Temperature Range | -65°C to +175°C - enables operation in extreme environments including space and engine bays |
| Thermal Resistance (RθJEC) | 20°C/W junction-to-end-cap - dictates heatsinking requirement when mounted to metal substrate |
| Reverse Leakage (IR) | 1.0 µA at 4.7 V - ensures minimal standby current in high-impedance bias networks |
| Forward Voltage (VF) | 1.0 V at 200 mA - defines conduction loss during forward-biased protection events |
Pinout & Package
Hermetically sealed voidless glass MELF (D-5A) package with tungsten slugs and tin/lead or RoHS-compliant matte tin terminals. Cathode indicated by single polarity band; no anode/cathode labeling beyond band. Weight: 193 mg.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (banded end) | Regulated output node | Connected to system ground or reference rail; voltage develops across cathode–anode during Zener conduction |
| Anode (unbanded end) | Current return path | Connected to unregulated input; completes current loop during reverse-bias regulation |
Key Features
| Feature | Design Value |
|---|---|
| Voidless hermetic glass construction | Eliminates moisture ingress and internal delamination, ensuring >20-year shelf life and field reliability in sealed enclosures |
| Category III internal metallurgical bond | Provides superior thermal and mechanical interface between silicon die and tungsten slug, enabling survivability under shock/vibration per MIL-STD-883 |
| MIL-PRF-19500/406 JANTXV qualification | Validates performance across full temperature range, burn-in, and life testing for mission-critical defense systems |
| Triple-layer passivation | Reduces surface leakage and enhances stability of Zener voltage under humidity and ionizing radiation exposure |
Applications
| Avionics Power Reference | Rad-Hard Satellite Regulator |
|---|---|
Use Scenario: Precision 5.6 V reference generation in F-35 flight control power sequencers where voltage drift must remain <±10 mV over -55°C to +125°C. IC Role / Device Role / Timing Role: Shunt voltage regulator providing stable bias for op-amp comparators and ADC references. Use Value: 5 Ω dynamic impedance and <0.25 µA leakage ensure <0.5 mV output variation across 1–50 mA load range. |
Use Scenario: Overvoltage clamp in LEO satellite solar array regulators exposed to total ionizing dose >100 krad(Si). IC Role / Device Role / Timing Role: Radiation-hardened Zener clamp protecting downstream DC-DC converters from transient surges. Use Value: Inherent radiation hardness per MicroNote 050 and Category III bond maintain VZ stability after 100 krad(Si) exposure. |
| Tactical Radio Bias Network | Military Sensor Signal Conditioning |
Use Scenario: Stable biasing of RF front-end LNAs in AN/PRC-163 manpack radios operating in desert environments (85°C ambient). IC Role / Device Role / Timing Role: Zener shunt regulator establishing fixed gate bias for GaAs FETs. Use Value: -65°C to +175°C junction rating and 20°C/W RθJEC allow direct end-cap mounting to aluminum chassis for passive cooling. |
Use Scenario: Low-noise voltage reference for MEMS inertial measurement units (IMUs) in guided munitions guidance sections. IC Role / Device Role / Timing Role: Precision shunt regulator supplying excitation voltage to Wheatstone bridge sensors. Use Value: 5.6 V ±5% tolerance and <1 µA leakage minimize offset drift and enable sub-mV sensor resolution. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N6490US | Zener voltage 5.1 V (vs. 5.6 V); identical package, power rating, and MIL qualification | Used where lower reference voltage required without changing layout or thermal design | Select when circuit requires 5.1 V regulation with same reliability and thermal behavior |
| 1N6489US | Zener voltage 4.7 V; otherwise matches 1N6491US in package, power, and qualification level | Suitable for legacy designs specifying 4.7 V reference or tighter low-voltage margining | Choose for backward compatibility with 4.7 V reference schematics while retaining JANTXV assurance |
Compared with 1N6491US, the 1N6490US and 1N6489US offer identical mechanical, thermal, and qualification profiles but shift the Zener voltage to 5.1 V and 4.7 V respectively - enabling voltage-scaling flexibility without redesigning PCB layout, heatsinking, or reliability validation.
Availability
1N6491US is available at Aetrix Electronics and suitable for avionics power reference, rad-hard satellite regulation, and tactical radio bias networks requiring stable component supply with guaranteed MIL-PRF-19500/406 compliance and traceable lot history.
Supply support for 1N6491US 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 analog and mixed-signal components for aerospace, defense, and industrial markets.
The 1N6491US belongs to Microsemi's military-qualified MELF Zener diode family, designed specifically for voltage regulation in mission-critical systems where failure is not an option - emphasizing hermeticity, radiation tolerance, and extended temperature operation.
FAQ
What is the Zener voltage tolerance for the 1N6491US?
The 1N6491US has a nominal Zener voltage of 5.6 V with a standard tolerance of ±5%, as defined in the Electrical Characteristics table on page 3 of T4-LDS-0183-1. No suffix indicates this 5% tolerance; tighter tolerances (±2% or ±1%) require different part number suffixes (C or D) and are not applicable to the base 1N6491US designation.
Is the 1N6491US RoHS compliant?
The 1N6491US is available in both RoHS-compliant (e3 suffix) and non-RoHS versions, but only the commercial-grade variant supports RoHS compliance. JANTXV-qualified units like the standard 1N6491US use Sn/Pb terminations per MIL-PRF-19500/406 requirements and are not RoHS compliant unless explicitly ordered with e3 marking.
What does "Category III metallurgical bond" mean for the 1N6491US?
Category III refers to Microsemi's highest-grade internal die-to-substrate metallurgical bond, used for the 1N6485US–1N6491US series. It provides enhanced thermal conductivity and mechanical integrity versus Category I bonds, supporting sustained operation under high thermal stress and mechanical vibration - verified per MIL-STD-883 test methods.
Can the 1N6491US be soldered using standard reflow profiles?
Yes - the 1N6491US supports a peak solder temperature of 260°C for 10 seconds, as specified in the Maximum Ratings table. This aligns with standard leaded and lead-free reflow profiles. Care must be taken to avoid thermal shock; preheating and controlled ramp rates are recommended to preserve hermetic seal integrity.
How does the thermal impedance curve for the 1N6491US differ from other devices in the series?
The 1N6491US follows Figure 4 in the datasheet - the Thermal Impedance Curve for 1N6485US through 1N6491US and 1N4460US through 1N4461US. This curve reflects its specific glass/MELF construction and tungsten slug geometry, differing from the 1N4462US–1N4496US group (Figure 3) due to distinct thermal mass and interface characteristics.
1N6491US Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- SQ-MELF, A
- Packaging:
- Bulk
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 5.6 V
- Tolerance:
- ±5%
- Power - Max:
- 1.5 W
- Impedance (Max) (Zzt):
- 5 Ohms
- Current - Reverse Leakage @ Vr:
- 500 nA @ 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:
- A, SQ-MELF
1N6491US FAQ
1.How can I place an order for 1N6491US through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N6491US 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 1N6491US reliable?
The price and inventory of 1N6491US are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N6491US is usually 5 days.
3.What payment methods are accepted for 1N6491US?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N6491US transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N6491US?
1N6491US orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N6491US 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 1N6491US?
For technical support, including 1N6491US datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N6491US requirements.
6.How does Aetrix verify that 1N6491US is sourced from the original manufacturer or authorized distributors?
All 1N6491US 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 1N6491US meets industry standards.
7.What is the process for return or replacement of 1N6491US?
All 1N6491US units undergo pre-shipment inspection (PSI). If there is an issue with 1N6491US, 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 1N6491US part is unused and in its original packaging.
Return procedure for 1N6491US:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1N6491US Tags
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MMBZ5240B-7-F
Diodes Incorporated
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BZT52C5V6T-7
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Diodes Incorporated
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Diodes Incorporated
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onsemi
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Diodes Incorporated
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MM5Z5V1ST1G
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SMAJ4744A-TP
Micro Commercial Co
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BZT52C3V6LP-7
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SMAZ12-13-F
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