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Microchip Technology 1N5278A
- Part No.:
- 1N5278A
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- DO-204AH, DO-35, Axial
- Datasheet:
-
1N5278A.pdf
- Description:
- DIODE ZENER 170V 500MW DO204AH
- Quantity:
- Payment:
- Shipping:
Inventory:7,302
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Product details
Overview
1N5278A from Microsemi is a 500 mW, 170 V Zener diode in DO-35 glass axial-leaded package with ±10% voltage tolerance, 0.74 mA test current, and 5500 Ω dynamic impedance at 0.25 mA; used for precision voltage reference and overvoltage protection in industrial power supplies.
For engineers reviewing the 1N5278A datasheet, 1N5278A pinout, 1N5278A application, or 1N5278A equivalent, this page delivers verified electrical specs, thermal derating behavior, Zener voltage temperature coefficient (+0.110 %/°C), and direct alternatives for stable voltage regulation in high-temperature environments.
Technical Context
The 1N5278A operates as a two-terminal reverse-biased voltage regulator with sharp breakdown knee confirmed by dual-point Zener impedance measurement per MicroNote 202. Its 170 V nominal Zener voltage is specified at IZT = 0.74 mA with guaranteed limits on VZ, IR, and VF per JEDEC registration.
Thermal performance is defined by 250 °C/W junction-to-lead resistance at 10 mm lead length and 310 °C/W junction-to-ambient on FR4 board; forward voltage remains ≤1.5 V at 200 mA, supporting bidirectional transient clamping verification.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Nominal Zener Voltage (VZ) | 170 V @ IZT = 0.74 mA - sets precise regulation threshold for high-voltage feedback loops |
| Zener Tolerance | ±10% (A suffix) - defines worst-case output voltage window in production designs |
| Power Dissipation | 500 mW at 25°C - determines maximum continuous regulation power before thermal derating |
| Zener Impedance (ZZK) | 5500 Ω @ IZK = 0.25 mA - indicates high dynamic resistance affecting regulation stability under light loads |
| Temperature Coefficient (αVZ) | +0.110 %/°C - quantifies positive drift of VZ over temperature, critical for wide-range ambient operation |
| Max Reverse Current (IR) | 10 μA @ VR = 136 V - defines leakage-limited hold-off capability below breakdown |
| Operating Temperature | –65°C to +175°C - enables use in aerospace, downhole, and military-grade systems |
Pinout & Package
DO-35 (DO-204AH) hermetically sealed glass axial-leaded 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 | Ground-reference terminal in Zener configuration | Connected to system ground or low-side return path during regulation |
| Cathode | Input/reference terminal in Zener configuration | Banded end; connected to unregulated input rail to clamp voltage at 170 V ±10% |
Key Features
| Feature | Design Value |
|---|---|
| Radiation hardness | Inherently radiation hard per MicroNote 050 - suitable for space-qualified power monitoring |
| ESD immunity | Nonsensitive to ESD per MIL-STD-750 Method 1020 - eliminates need for external ESD protection in handling |
| Minimal capacitance | Low CJ per Figure 2 - preserves high-frequency signal integrity in RF bias networks |
| Military screening options | Available with MQ/MX/MV/MSP prefixes for JAN/JANTX/JANTXV/JANS levels - supports defense-critical BOMs |
| RoHS compliance | e3 suffix option - meets environmental compliance without performance trade-off |
Applications
| High-Voltage Power Supply Reference | Overvoltage Protection Clamp |
|---|---|
Use Scenario: Regulating feedback node in 200 V DC-DC converter secondary side. IC Role / Device Role / Timing Role: Voltage reference element setting output accuracy via optocoupler feedback loop. Use Value: 170 V ±10% Zener threshold ensures safe margin below 200 V rail while maintaining tight load regulation across –65°C to +175°C. |
Use Scenario: Clamping surge transients on industrial PLC analog input lines. IC Role / Device Role / Timing Role: Two-terminal shunt protector absorbing >1 kV spikes above 170 V threshold. Use Value: 500 mW power rating and 250 °C/W thermal resistance enable reliable energy dissipation without thermal runaway. |
| Temperature-Stable Sensor Bias | Aerospace Voltage Monitor |
Use Scenario: Providing bias voltage to high-temperature RTD signal conditioning circuitry. IC Role / Device Role / Timing Role: Stable reference source compensating for sensor nonlinearity over extended temperature range. Use Value: +0.110 %/°C αVZ allows predictable calibration offset correction in firmware, reducing hardware trimming. |
Use Scenario: Monitoring bus voltage in satellite power distribution unit with radiation exposure. IC Role / Device Role / Timing Role: Radiation-hardened voltage threshold detector triggering fault isolation logic. Use Value: Inherent radiation hardness per MicroNote 050 eliminates need for shielding or redundancy in LEO missions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N5278B | ±5% tolerance (vs. ±10% for 1N5278A); identical VZ, IZT, ZZK, and thermal specs | Higher precision required in closed-loop feedback where ±5% VZ variation improves output accuracy | Select 1N5278B when tighter regulation tolerance justifies cost premium and layout accommodates same DO-35 footprint |
| MMBZ5278B | SOT-23 surface-mount package; same 170 V ±5%, but lower 225 mW power rating and 300 °C/W thermal resistance | Space-constrained PCBs where axial leads are impractical, accepting reduced power handling and thermal margin | Choose MMBZ5278B only for low-power signal-level clamping; not suitable for 500 mW continuous regulation like 1N5278A |
Compared with 1N5278B and MMBZ5278B, the 1N5278A offers the broadest operating temperature range (–65°C to +175°C) and highest continuous power handling (500 mW), making it optimal for ruggedized, high-reliability systems where axial mounting and thermal robustness are prioritized over tolerance tightness or footprint size.
Availability
1N5278A is available at Aetrix Electronics and suitable for high-voltage power supply reference, overvoltage protection clamp, and aerospace voltage monitor applications requiring stable component supply across extended temperature and radiation environments.
Supply support for 1N5278A 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, radiation-hardened, and high-voltage analog components for aerospace, defense, and industrial markets.
The 1N52xx series was designed specifically for precision voltage regulation in harsh-environment power systems, emphasizing wide temperature operation, JEDEC-standard reliability, and compatibility with military screening standards.
FAQ
What is the nominal Zener voltage and test current for the 1N5278A?
The 1N5278A has a nominal Zener voltage of 170 V measured at a test current (IZT) of 0.74 mA. This value is guaranteed per JEDEC registration and applies under stabilized thermal conditions with 10 mm lead length from the case. The 1N5278A maintains this specification across its full operating temperature range of –65°C to +175°C.
Does the 1N5278A have a specified Zener impedance, and at what condition is it measured?
Yes, the 1N5278A has a maximum Zener impedance (ZZK) of 5500 Ω measured at IZK = 0.25 mA. This dynamic impedance reflects the device's regulation stiffness under light-load conditions and is verified using dual-point AC superposition per MicroNote 202 to ensure a sharp breakdown knee and eliminate unstable units.
What is the temperature coefficient of the 1N5278A, and how does it affect design?
The 1N5278A has a Zener voltage temperature coefficient (αVZ) of +0.110 %/°C, measured from 25°C to 125°C at rated IZT. This positive drift means VZ increases predictably with temperature, enabling firmware-based compensation in high-accuracy sensor biasing or reference applications where the 1N5278A serves as a stable, calibrated element.
Can the 1N5278A be used in military or aerospace applications?
Yes, the 1N5278A supports military-grade deployment through optional prefixes: MQ (JAN), MX (JANTX), MV (JANTXV), or MSP (JANS) when ordered with the "–1" internal bond suffix. These variants meet MIL-PRF-19500 screening requirements and leverage the 1N5278A's inherent radiation hardness per MicroNote 050 and extended –65°C to +175°C operating range.
What packaging and plating options are available for the 1N5278A?
The 1N5278A is supplied in the DO-35 (DO-204AH) hermetically sealed glass axial-leaded package. Standard plating is tin-lead; RoHS-compliant matte-tin plating is available with the "e3" suffix. Tape-and-reel packaging is offered with the "TR" suffix per EIA-296, and marking includes the full part number on the glass body.
1N5278A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- DO-204AH, DO-35, Axial
- Packaging:
- Bulk
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 170 V
- Tolerance:
- ±10%
- Power - Max:
- 500 mW
- Impedance (Max) (Zzt):
- 1900 Ohms
- Current - Reverse Leakage @ Vr:
- 100 nA @ 129 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.5 V @ 200 mA
- Operating Temperature:
- -65°C ~ 175°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-204AH (DO-35)
1N5278A FAQ
1.How can I place an order for 1N5278A through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N5278A 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 1N5278A reliable?
The price and inventory of 1N5278A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N5278A is usually 5 days.
3.What payment methods are accepted for 1N5278A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N5278A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N5278A?
1N5278A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N5278A 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 1N5278A?
For technical support, including 1N5278A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N5278A requirements.
6.How does Aetrix verify that 1N5278A is sourced from the original manufacturer or authorized distributors?
All 1N5278A 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 1N5278A meets industry standards.
7.What is the process for return or replacement of 1N5278A?
All 1N5278A units undergo pre-shipment inspection (PSI). If there is an issue with 1N5278A, 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 1N5278A part is unused and in its original packaging.
Return procedure for 1N5278A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1N5278A Tags
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