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Home > Products > Discrete Semiconductor Products > Diodes > Zener > Single Zener Diodes

Microchip Technology 1N981A

Name: 1N981A
Brand: Microchip Technology
SKU: 1N981A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 1N981A

Manufacturer:: Microchip Technology

Category:: Single Zener Diodes

Package:: DO-204AA, DO-7, Axial

Datasheet:: 1N981A.pdf

Description:: DIODE ZENER 68V 500MW DO7

Quantity:: RFQ Add To RFQ list

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Product details

Overview

1N981A from Microsemi is a silicon 500 mW axial-lead Zener diode in DO-35 (DO-204AH) package, rated for 68 V nominal Zener voltage with ±10% tolerance, 1.8 mA Zener test current, and 230 Ω dynamic impedance at I_ZT. It operates across –65°C to +175°C and delivers stable voltage regulation in low-power reference and protection circuits.

For engineers reviewing the 1N981A datasheet, 1N981A pinout, 1N981A application, or 1N981A equivalent, key selection factors include its 68 V regulation level, ±10% tolerance (A suffix), 0.5 W power rating at 50°C lead temperature, DO-35 mechanical compatibility, and cathode-band polarity marking for correct orientation in shunt regulation designs.

Technical Context

The 1N981A functions as a two-terminal shunt voltage regulator, conducting in reverse breakdown when cathode voltage exceeds anode by ≥68 V. Its Zener knee is characterized at 1.8 mA test current, with 230 Ω dynamic impedance measured under 10% AC ripple superimposed on DC bias.

Thermal design relies on junction-to-lead resistance of 250 °C/W (3/8″ lead length) and junction-to-ambient resistance of 310 °C/W on FR4 board; maximum steady-state dissipation is 480 mW at T_L < 50°C but derates linearly above that threshold.

Key Specifications

Parameter	Value and Actual Design Meaning
Nominal Zener Voltage	68 V ±10% - defines regulated output voltage under specified test conditions; actual regulation range spans 61.2 V to 74.8 V.
Zener Test Current (I_ZT)	1.8 mA - minimum current required to achieve nominal V_Z; critical for setting bias resistor value in shunt regulator design.
Zener Impedance (Z_ZT)	230 Ω @ I_ZT - quantifies voltage variation per mA change in current; impacts regulation stability under load transients.
Max DC Zener Current (I_ZM)	5.5 mA - maximum continuous reverse current before exceeding 400 mW dissipation at 75°C lead temperature.
Reverse Leakage Current	5 μA @ 51.7 V - ensures minimal quiescent current below breakdown; critical for low-power standby circuits.
Temp. Coefficient (αV_Z)	+0.097 %/°C - positive drift means V_Z increases ~66 mV/°C at 68 V; must be compensated in precision references.
Forward Voltage	1.3 V max @ 200 mA - specifies forward conduction drop; relevant for polarity protection or dual-use rectifier applications.
Operating Temperature	–65°C to +175°C - enables use in aerospace, downhole, and industrial environments without derating.

Pinout & Package

Package: DO-35 (DO-204AH), hermetically sealed glass axial-leaded case with tin-lead or RoHS-compliant matte-tin plating; cathode identified by single black band.

Pin/Terminal	Circuit Role	Design Meaning
Anode (unbanded end)	Reference ground node	Connected to system ground or lowest potential point; establishes reference for Zener regulation.
Cathode (banded end)	Regulated output node	Connected to input supply rail; maintains voltage at ~68 V relative to anode when reverse-biased above breakdown.

Key Features

Feature	Design Value
JEDEC-registered 1N981A	Guarantees standardized electrical behavior and interchangeability across qualified suppliers per JEDEC spec.
±10% Zener voltage tolerance (A suffix)	Enables cost-effective voltage clamping where tight regulation is not required, such as overvoltage protection.
0.5 W power rating at T_L ≤ 50°C	Supports robust transient suppression in 24 V–48 V industrial control rails without external heatsinking.
Nonsensitive to ESD (MIL-STD-750 Method 1020)	Eliminates need for pre-assembly ESD handling protocols during manual soldering or board assembly.
Inherent radiation hardness	Validated per Microsemi MicroNote 050; suitable for space-qualified or high-reliability nuclear instrumentation systems.

Applications

Industrial Power Supply Protection	Automotive ECU Reference Clamping
Use Scenario: Clamp transient spikes on 48 V battery-fed control modules during load dump events. IC Role / Device Role / Timing Role: Shunt regulator absorbing surge energy to hold downstream circuit voltage ≤75 V. Use Value: Prevents damage to 5 V/3.3 V LDOs and microcontrollers using only passive components and no active control loop.	Use Scenario: Stabilize 5 V reference rail against alternator ripple and ignition noise in engine control units. IC Role / Device Role / Timing Role: Precision voltage clamp maintaining reference integrity despite wide ambient temperature swings. Use Value: Ensures ADC accuracy remains within ±0.5% over –40°C to +125°C operating range without calibration.
Aerospace Sensor Biasing	Test Equipment Calibration Reference
Use Scenario: Provide stable bias voltage for piezoresistive pressure transducers in flight data recorders. IC Role / Device Role / Timing Role: Low-drift Zener source compensating for sensor offset drift across thermal cycles. Use Value: Achieves <10 ppm/°C effective reference stability when combined with matched resistor networks.	Use Scenario: Serve as secondary voltage standard in portable multimeter self-test routines. IC Role / Device Role / Timing Role: Fixed 68 V reference enabling internal DAC linearity verification at mid-scale. Use Value: Reduces calibration dependency on external standards while maintaining traceable 0.1% accuracy.

Industrial Power Supply Protection

Automotive ECU Reference Clamping

Use Scenario: Clamp transient spikes on 48 V battery-fed control modules during load dump events.

IC Role / Device Role / Timing Role: Shunt regulator absorbing surge energy to hold downstream circuit voltage ≤75 V.

Use Value: Prevents damage to 5 V/3.3 V LDOs and microcontrollers using only passive components and no active control loop.

Use Scenario: Stabilize 5 V reference rail against alternator ripple and ignition noise in engine control units.

IC Role / Device Role / Timing Role: Precision voltage clamp maintaining reference integrity despite wide ambient temperature swings.

Use Value: Ensures ADC accuracy remains within ±0.5% over –40°C to +125°C operating range without calibration.

Aerospace Sensor Biasing

Test Equipment Calibration Reference

Use Scenario: Provide stable bias voltage for piezoresistive pressure transducers in flight data recorders.

IC Role / Device Role / Timing Role: Low-drift Zener source compensating for sensor offset drift across thermal cycles.

Use Value: Achieves <10 ppm/°C effective reference stability when combined with matched resistor networks.

Use Scenario: Serve as secondary voltage standard in portable multimeter self-test routines.

IC Role / Device Role / Timing Role: Fixed 68 V reference enabling internal DAC linearity verification at mid-scale.

Use Value: Reduces calibration dependency on external standards while maintaining traceable 0.1% accuracy.

Equivalent & Alternatives

The following parts are listed as comparable options for similar Zener regulation applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
1N981B	Same 68 V nominal voltage but ±5% tolerance (B suffix) and 1.8 mA I_ZT, 230 Ω Z_ZT.	Higher precision regulation required; tighter tolerance reduces worst-case voltage spread in feedback loops.	Select 1N981B when closed-loop stability or ADC reference accuracy demands ≤±3.4 V variation.
MMBZ5255B (ON Semiconductor)	SMD SOT-23 package; 68 V ±5%, 1.8 mA I_ZT, 230 Ω Z_ZT; 200 mW rating vs. 500 mW.	Space-constrained PCBs where through-hole DO-35 mounting is impractical.	Choose MMBZ5255B only if thermal management allows full 200 mW dissipation and layout cannot accommodate axial leads.

Compared with 1N981A, the 1N981B offers tighter voltage control at identical power and impedance, while MMBZ5255B trades package size and power rating for surface-mount compatibility-neither is pin-compatible, and both require layout or thermal redesign.

Availability

1N981A is available at Aetrix Electronics and suitable for industrial power supply protection, automotive ECU reference clamping, and aerospace sensor biasing requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 1N981A 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 analog, RF, and radiation-hardened components for defense, aerospace, and industrial markets.

The 1N957B–1N992B series was designed specifically for ruggedized voltage regulation in mission-critical systems where extended temperature operation, ESD immunity, and long-term parametric stability are mandatory.

FAQ

What is the Zener voltage tolerance for 1N981A?

The "A" suffix in 1N981A denotes a ±10% tolerance on the nominal 68 V Zener voltage, meaning the actual breakdown voltage falls between 61.2 V and 74.8 V at 25°C with 1.8 mA test current. This wider tolerance supports cost-sensitive overvoltage protection applications where absolute precision is secondary to robustness and availability. The 1N981A meets JEDEC registration requirements for this tolerance grade.

Can 1N981A be used in surface-mount designs?

No-1N981A is packaged exclusively in the axial-leaded DO-35 (DO-204AH) glass case and requires through-hole mounting. For surface-mount equivalents, consider Microsemi's MLL981B in DO-213AA (MELF) or ON Semiconductor's MMBZ5255B in SOT-23. Substituting 1N981A into an SMT footprint would require mechanical adaptation and violates its qualified thermal path; the 1N981A's 250 °C/W junction-to-lead resistance assumes 3/8″ axial lead length.

What is the maximum power dissipation for 1N981A at 75°C lead temperature?

At 75°C lead temperature (measured 3/8″ from body), the 1N981A is rated for 400 mW maximum continuous power dissipation, corresponding to a Zener current limit of 5.5 mA. This is derived from the device's thermal resistance and junction temperature limits. Exceeding this current risks thermal runaway, especially given the +0.097 %/°C temperature coefficient. The 1N981A datasheet specifies I_ZM = 5.5 mA explicitly for this condition.

How does the temperature coefficient affect 1N981A performance in automotive applications?

The +0.097 %/°C temperature coefficient causes the 1N981A's Zener voltage to increase by approximately 66 mV per °C rise at 68 V. Over a –40°C to +125°C automotive range, this results in a total shift of ~10.9 V-requiring design margin or compensation in precision references. However, for clamping applications like load-dump protection, this drift is acceptable since the 1N981A still holds voltage below destructive thresholds across the full range.

Is 1N981A RoHS compliant?

The base 1N981A part number is not RoHS compliant; RoHS compliance requires the "e3" suffix (e.g., 1N981Ae3), indicating annealed matte-tin plating instead of traditional tin-lead. Microsemi documents this option in the "Features" section of the datasheet. Standard 1N981A uses Sn/Pb terminations per MIL-STD-750 Method 2026, so environmental compliance must be verified via the full marked part number on the device body or reel label.

1N981A Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

Package/Case:: DO-204AA, DO-7, Axial

Packaging:: Bulk

Product Status:: Active

Voltage - Zener (Nom) (Vz):: 68 V

Tolerance:: ±10%

Power - Max:: 500 mW

Impedance (Max) (Zzt):: 230 Ohms

Current - Reverse Leakage @ Vr:: 5 µA @ 51.7 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-7

1N981A FAQ

1.How can I place an order for 1N981A through Aetrix?

Please submit a Request for Quotation (RFQ) for 1N981A 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 1N981A reliable?

The price and inventory of 1N981A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N981A is usually 5 days.

3.What payment methods are accepted for 1N981A?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N981A transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 1N981A?

1N981A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 1N981A 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 1N981A?

For technical support, including 1N981A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N981A requirements.

6.How does Aetrix verify that 1N981A is sourced from the original manufacturer or authorized distributors?

All 1N981A 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 1N981A meets industry standards.

7.What is the process for return or replacement of 1N981A?

All 1N981A units undergo pre-shipment inspection (PSI). If there is an issue with 1N981A, 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 1N981A part is unused and in its original packaging.

Return procedure for 1N981A:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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