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Microchip Technology 1N4256SM
- Part No.:
- 1N4256SM
- Manufacturer:
- Microchip Technology
- Category:
- Single Diodes
- Package:
- SQ-MELF, S
- Datasheet:
-
1N4256SM.pdf
- Description:
- DIODE GP 2.5KV 250MA S SQ-MELF
- Quantity:
- Payment:
- Shipping:
Inventory:8,796
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Product details
Overview
1N4256SM from Microsemi is a hermetically sealed, voidless-glass high-voltage standard recovery rectifier diode rated for 2500 V working peak reverse voltage (VRWM), 0.25 A average forward current at 55 °C, and 10 µA max reverse leakage at VRWM. It features triple-layer passivation, low thermal resistance (38 °C/W), and operates from –65 °C to +175 °C. It is used in radar transmitters, X-ray power supplies, and high-reliability military half-bridge rectification.
For engineers reviewing the 1N4256SM datasheet, 1N4256SM pinout, 1N4256SM application, or 1N4256SM equivalent, key selection criteria include its MIL-PRF-19500/279 qualification status (commercial grade only), S-package glass construction, cathode-band polarity marking, and verified 2500 V VRWM with 3.5 V max VF at 100 mA.
Technical Context
This diode belongs to Microsemi's legacy high-reliability rectifier family designed for stable operation under extreme temperature and voltage stress. Its voidless hermetic glass package ensures long-term hermeticity and radiation hardness per MicroNote 050, while tungsten slugs enable robust thermal conduction.
The 1N4256SM exhibits standard recovery behavior with no soft-recovery or fast-recovery optimization. Its electrical characteristics are specified across –65 °C to +175 °C, with reverse leakage tightly controlled at ≤1 µA @ 25 °C and ≤20 µA @ +100 °C at VRWM = 2500 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 2500 V - Maximum sustainable peak reverse voltage across full operating temperature range without breakdown. |
| IO @ 55 °C | 0.25 A - Continuous average forward current capability with 55 °C ambient, defining usable DC output in power supply designs. |
| VF @ 100 mA | 3.5 V max - Forward voltage drop at nominal test current, directly impacting conduction loss and thermal design margin. |
| IR @ VRWM | 1 µA max @ 25 °C - Low reverse leakage ensures minimal standby power loss and signal integrity in high-impedance bias networks. |
| TJ Range | –65 °C to +175 °C - Extended junction temperature range supports deployment in aerospace, downhole, and military environments. |
| RθJL | 38 °C/W - Thermal resistance from junction to lead enables accurate heatsinking when mounted with 3/8″ lead length. |
| IZSM | 10 A @ 8.3 ms - Non-repetitive surge rating defines survivability during line transients or capacitor-charging events. |
Pinout & Package
1N4256SM uses the S-package: hermetically sealed voidless hard glass case with tungsten slugs and tin/lead or RoHS-compliant matte tin over copper terminals. Cathode is marked by a visible band on the glass body. Weight ≈ 400 mg.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward current entry point | Connected to AC source or transformer secondary in half-wave or bridge configurations; requires mechanical support due to glass-body fragility. |
| Cathode | Forward current exit point | Marked by colored band; connects to load or filter capacitor; polarity must be observed to prevent reverse-bias failure. |
Key Features
| Feature | Design Value |
|---|---|
| Voidless hermetic glass seal | Eliminates internal moisture and gas migration, ensuring >20-year shelf life and reliability in vacuum or high-humidity environments. |
| Triple-layer passivation | Provides enhanced surface insulation and resistance to ion contamination, critical for high-voltage stability in space-grade applications. |
| Lowest reverse leakage in class | ≤1 µA @ 25 °C / VRWM enables use in precision high-impedance biasing and low-power standby circuits without leakage-induced drift. |
| MIL-PRF-19500/279 compliance (commercial) | Meets screening, testing, and traceability requirements for defense electronics procurement, including lot traceability and burn-in. |
| Radiation hardness | Inherently resistant to total ionizing dose (TID) per Microsemi MicroNote 050, supporting use in low-earth orbit and nuclear instrumentation. |
Applications
| Radar Transmitter Power Supply | X-Ray Generator Rectification |
|---|---|
Use Scenario: High-voltage DC generation for magnetron or klystron anode supplies in pulsed radar systems. IC Role / Device Role / Timing Role: High-voltage standard recovery rectifier in voltage-doubler or Cockcroft-Walton multiplier stages. Use Value: 2500 V VRWM and 10 A surge rating ensure reliable operation during repetitive high-energy pulses without avalanche degradation. | Use Scenario: Converting high-frequency AC from resonant inverters into stable DC for X-ray tube acceleration. IC Role / Device Role / Timing Role: Primary rectifying element in high-efficiency, high-isolation HV power modules. Use Value: Voidless glass package prevents internal arcing under 100+ kV transient stress; low IR minimizes dark current in imaging chain. |
| Military Half-Bridge Converter | Industrial HV Power Supply |
Use Scenario: Input rectification stage in airborne or shipboard 28 VDC-to-HV conversion systems requiring MIL-S-901D shock compliance. IC Role / Device Role / Timing Role: High-reliability, high-temperature rectifier in dual-diode half-bridge configuration with forced-air cooling. Use Value: –65 °C to +175 °C operation and 38 °C/W RθJL allow direct mounting to chassis without additional heatsink in constrained enclosures. | Use Scenario: Front-end rectification in industrial electrostatic precipitators and ozone generators operating continuously at 40–60 °C ambient. IC Role / Device Role / Timing Role: Standard recovery diode handling 0.25 A average current at elevated temperature with minimal derating. Use Value: 0.25 A IO @ 55 °C and 0.15 A @ 100 °C provide predictable thermal margin without complex derating curves. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-voltage rectifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4256 | Same electrical specs and package, but non-RoHS commercial version without "SM" suffix; tin/lead termination. | No RoHS compliance; unsuitable for EU-based medical or consumer-facing industrial equipment. | Select 1N4256SM when RoHS compliance and matte tin finish are required for final assembly. |
| 1N3646 | Identical VRWM (2500 V), same S-package, but lower IO (0.25 A @ 55 °C → 0.10 A @ 100 °C vs. 0.15 A for 1N4256SM). | Reduced high-temperature current capability limits use in thermally constrained enclosures above 85 °C ambient. | Choose 1N3646 only if cost sensitivity outweighs thermal margin needs and RoHS is not required. |
Compared with 1N4256 and 1N3646, the 1N4256SM delivers identical high-voltage performance with improved high-temperature current rating and mandatory RoHS-compliant matte tin plating-making it the preferred choice for new designs targeting export compliance and extended thermal operation.
Availability
1N4256SM is available at Aetrix Electronics and suitable for radar transmitter power supplies, X-ray generator rectification, and military half-bridge converters requiring stable component supply, long-lifecycle assurance, and traceable sourcing.
Supply support for 1N4256SM 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 RF solutions for aerospace, defense, and industrial markets.
The 1N4256SM belongs to Microsemi's legacy high-voltage rectifier product line, engineered specifically for mission-critical applications demanding hermeticity, radiation tolerance, and extended temperature operation beyond commercial-grade limits.
FAQ
What is the maximum working peak reverse voltage (VRWM) for the 1N4256SM?
The 1N4256SM has a VRWM of 2500 V, meaning it can sustain up to 2500 volts peak reverse voltage across its terminals over the full operating temperature range (–65 °C to +175 °C) without breakdown. This rating is confirmed in the Electrical Characteristics table on page 4 of T4-LDS-0266 Rev. 2 and defines the upper limit for safe DC blocking in rectifier applications.
Does the 1N4256SM meet MIL-PRF-19500/279 qualification?
The 1N4256SM is a commercial-grade part compliant with MIL-PRF-19500/279 screening requirements, including environmental testing, lot traceability, and burn-in. Unlike the JAN/JANTX variants (e.g., 1N3644–1N3647), the 1N4256SM does not carry JAN or JANTX level markings but satisfies the specification for commercial procurement under this standard.
What is the forward voltage drop (VF) specification for the 1N4256SM?
The 1N4256SM has a maximum forward voltage of 3.5 V at 100 mA and 25 °C, as specified in the Electrical Characteristics table. This value reflects conduction loss under typical low-current rectification conditions and is critical for calculating power dissipation and thermal design margins in high-voltage, low-current applications.
Is the 1N4256SM RoHS compliant?
Yes, the 1N4256SM is RoHS compliant, featuring matte tin termination over copper. Per the datasheet, RoHS versions are available for commercial-grade parts only, and the "SM" suffix explicitly denotes this compliance-distinguishing it from the non-RoHS 1N4256 variant with tin/lead plating.
What package type and polarity marking does the 1N4256SM use?
The 1N4256SM uses the S-package: a hermetically sealed voidless hard glass case with tungsten slugs and axial leads. Polarity is indicated by a visible cathode band on the glass body. The anode and cathode terminals are unmarked otherwise, requiring visual confirmation of the band before PCB placement or wiring.
1N4256SM Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- SQ-MELF, S
- Packaging:
- Bulk
- Product Status:
- Active
- Technology:
- Standard
- Voltage - DC Reverse (Vr) (Max):
- 2500 V
- Current - Average Rectified (Io):
- 250mA
- Voltage - Forward (Vf) (Max) @ If:
- 3.5 V @ 100 mA
- Speed:
- Standard Recovery >500ns, > 200mA (Io)
- Reverse Recovery Time (trr):
- -
- Current - Reverse Leakage @ Vr:
- 1 µA @ 2500 V
- Capacitance @ Vr, F:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- S, SQ-MELF
- Operating Temperature - Junction:
- -65°C ~ 175°C
1N4256SM FAQ
1.How can I place an order for 1N4256SM through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N4256SM 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 1N4256SM reliable?
The price and inventory of 1N4256SM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N4256SM is usually 5 days.
3.What payment methods are accepted for 1N4256SM?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N4256SM transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N4256SM?
1N4256SM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N4256SM 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 1N4256SM?
For technical support, including 1N4256SM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N4256SM requirements.
6.How does Aetrix verify that 1N4256SM is sourced from the original manufacturer or authorized distributors?
All 1N4256SM 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 1N4256SM meets industry standards.
7.What is the process for return or replacement of 1N4256SM?
All 1N4256SM units undergo pre-shipment inspection (PSI). If there is an issue with 1N4256SM, 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 1N4256SM part is unused and in its original packaging.
Return procedure for 1N4256SM:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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