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

onsemi 1N5921B

Name: 1N5921B
Brand: onsemi
SKU: 1N5921B
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 1N5921B

Manufacturer:: onsemi

Category:: Single Zener Diodes

Package:: DO-204AL, DO-41, Axial

Datasheet:: 1N5921B.pdf

Description:: DIODE ZENER 6.8V 3W AXIAL

Quantity:: RFQ Add To RFQ list

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Inventory:7,174

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Product details

Overview

1N5921B from onsemi is a 3 W, ±5% tolerance Zener diode in DO-41 package with nominal zener voltage of 6.8 V, maximum zener impedance of 55.1 Ω at 5.2 mA test current, and surge rating of 98 W at 1 ms. It serves as a precision voltage reference or shunt regulator in low-power DC power supplies and overvoltage protection circuits.

For engineers reviewing the 1N5921B datasheet, pinout, applications, or equivalent options, key selection criteria include its 6.8 V nominal regulation voltage, 55.1 Ω dynamic impedance at IZT = 5.2 mA, 200 µA leakage at VR = 5.2 V, ESD rating >16 kV (HBM), and axial DO-41 mechanical compatibility with legacy through-hole designs.

Technical Context

The 1N5921B operates as a silicon-oxide passivated junction Zener diode optimized for stable reverse-biased voltage regulation. Its design targets steady-state dissipation up to 3 W at TL = 75°C with 24 mW/°C derating above that temperature, and supports transient surge handling up to 98 W for 1 ms pulses without degradation.

It exhibits a typical temperature coefficient near zero for its 6.8 V rating (per Figure 5), enabling minimal drift across operating temperatures. The cathode-band polarity marking and axial DO-41 package ensure unambiguous orientation and compatibility with standard lead-forming and wave-soldering processes.

Key Specifications

Parameter	Value and Actual Design Meaning
Nominal Zener Voltage (V_Z)	6.8 V - precise regulation point at I_ZT = 5.2 mA under controlled thermal conditions
Zener Impedance (Z_ZT)	55.1 Ω max - low dynamic resistance ensures tight voltage regulation under varying load currents
Test Current (I_ZT)	5.2 mA - standardized bias point for guaranteed V_Z and Z_ZT specification compliance
Reverse Leakage (I_R)	200 µA max @ V_R = 5.2 V - low off-state current minimizes standby power loss
Surge Power Rating	98 W @ 1 ms - enables robust transient overvoltage clamping without failure
ESD Rating (HBM)	Class 3 (>16 kV) - high electrostatic discharge immunity simplifies handling and board assembly
Package	DO-41 (Case 59) - industry-standard axial plastic package with corrosion-resistant leads and 260°C solderability

Pinout & Package

DO-41 package: axial-leaded, void-free thermosetting plastic case with cathode indicated by a single color band. Leads are readily solderable; maximum soldering temperature is 260°C at 1/16″ from case for 10 seconds. Mounting position is unrestricted.

Pin/Terminal	Circuit Role	Design Meaning
Cathode (banded end)	Regulated output node	Connected to higher-potential rail; reverse-biased operation establishes stable V_Z drop
Anode	Reference/return node	Connected to circuit ground or lower-potential rail; completes Zener conduction path

Key Features

Feature	Design Value
±5% Zener voltage tolerance	Tight regulation window (6.46–7.14 V) reduces need for post-regulation trimming in cost-sensitive designs
3 W steady-state power dissipation	Enables use in higher-current shunt regulation without heatsinking in ambient ≤50°C environments
Surge rating of 98 W @ 1 ms	Provides reliable transient suppression for inductive kickback or ESD events in industrial control inputs
Pb-free (G suffix) packaging	Meets RoHS Directive 2011/65/EU and JEDEC J-STD-020 moisture sensitivity level 1 requirements
Silicon-oxide passivated junction	Ensures long-term parameter stability and low leakage drift over 10+ year operational lifetimes

Applications

Industrial Sensor Signal Conditioning	Low-Power Microcontroller Reset Circuit
Use Scenario: Stabilizing reference voltage for analog front-end amplifiers in 4–20 mA loop-powered transmitters. IC Role / Device Role / Timing Role: Shunt voltage reference providing fixed 6.8 V bias for op-amp rails and ADC references. Use Value: Low 55.1 Ω Z_ZT maintains regulation accuracy within ±1% across 1–10 mA load variations, critical for 12-bit sensor resolution.	Use Scenario: Generating a clean, temperature-stable reset threshold for 3.3 V microcontrollers during brown-out conditions. IC Role / Device Role / Timing Role: Zener-based voltage divider input to supervisor IC (e.g., MAX809) to trigger reset below 2.8 V. Use Value: Near-zero TC at 6.8 V minimizes reset threshold drift over −40°C to +85°C, eliminating calibration in field-deployed units.
DC-DC Converter Feedback Divider	Overvoltage Protection Clamp
Use Scenario: Setting regulated output voltage in isolated flyback converters using optocoupler feedback. IC Role / Device Role / Timing Role: Precision voltage reference in secondary-side TL431 replacement circuit where cost and simplicity are prioritized. Use Value: 6.8 V nominal V_Z allows direct interface with TL431's 2.495 V reference via resistor scaling, reducing BOM count.	Use Scenario: Clamping induced surges on 5 V logic rails exposed to relay coil switching or hot-plug events. IC Role / Device Role / Timing Role: Fast-acting shunt clamp absorbing transient energy before downstream ICs exceed absolute maximum ratings. Use Value: 98 W 1 ms surge rating handles 50 V/1 A spikes without parametric shift, verified per Figure 3 of datasheet.

Industrial Sensor Signal Conditioning

Low-Power Microcontroller Reset Circuit

Use Scenario: Stabilizing reference voltage for analog front-end amplifiers in 4–20 mA loop-powered transmitters.

IC Role / Device Role / Timing Role: Shunt voltage reference providing fixed 6.8 V bias for op-amp rails and ADC references.

Use Value: Low 55.1 Ω Z_ZT maintains regulation accuracy within ±1% across 1–10 mA load variations, critical for 12-bit sensor resolution.

Use Scenario: Generating a clean, temperature-stable reset threshold for 3.3 V microcontrollers during brown-out conditions.

IC Role / Device Role / Timing Role: Zener-based voltage divider input to supervisor IC (e.g., MAX809) to trigger reset below 2.8 V.

Use Value: Near-zero TC at 6.8 V minimizes reset threshold drift over −40°C to +85°C, eliminating calibration in field-deployed units.

DC-DC Converter Feedback Divider

Overvoltage Protection Clamp

Use Scenario: Setting regulated output voltage in isolated flyback converters using optocoupler feedback.

IC Role / Device Role / Timing Role: Precision voltage reference in secondary-side TL431 replacement circuit where cost and simplicity are prioritized.

Use Value: 6.8 V nominal V_Z allows direct interface with TL431's 2.495 V reference via resistor scaling, reducing BOM count.

Use Scenario: Clamping induced surges on 5 V logic rails exposed to relay coil switching or hot-plug events.

IC Role / Device Role / Timing Role: Fast-acting shunt clamp absorbing transient energy before downstream ICs exceed absolute maximum ratings.

Use Value: 98 W 1 ms surge rating handles 50 V/1 A spikes without parametric shift, verified per Figure 3 of datasheet.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
1N4734A	Same 6.8 V nominal V_Z, but ±5% tolerance, 1 W rating, higher Z_ZT = 7 Ω, DO-41 package	Limited to lower-power regulation; unsuitable for >150 mW continuous dissipation	Select when thermal budget is constrained and surge immunity is not required
BZX55C6V8	6.8 V nominal V_Z, ±5%, 500 mW rating, Z_ZT = 10 Ω, DO-35 package	Smaller footprint but lower surge capability (40 W) and reduced thermal mass	Prefer for space-constrained PCBs where 3 W dissipation is unnecessary

Compared with 1N5921B, the 1N4734A offers identical voltage but lower power and surge resilience, while the BZX55C6V8 trades package size and power rating for compactness-neither is pin-compatible due to differing thermal and surge performance envelopes.

Availability

1N5921B is available at Aetrix Electronics and suitable for industrial sensor interfaces, microcontroller reset circuits, DC-DC feedback networks, and overvoltage protection requiring stable component supply and long-lifecycle support.

Supply support for 1N5921B 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

onsemi (Semiconductor Components Industries, LLC) is a global semiconductor supplier specializing in energy-efficient power, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The 1N5921B belongs to the 1N5913B Series of 3 W Zener regulators designed for high-reliability voltage reference and shunt regulation in harsh-environment applications where stability, surge immunity, and Pb-free compliance are mandatory.

FAQ

What is the nominal zener voltage and tolerance of the 1N5921B?

The 1N5921B has a nominal zener voltage of 6.8 V with a tolerance of ±5%, meaning its actual measured V_Z falls between 6.46 V and 7.14 V when tested at I_ZT = 5.2 mA and T_L = 30°C. This tolerance is explicitly designated by the "B" suffix per onsemi's ordering nomenclature and confirmed in Table 3 of the datasheet.

What is the maximum steady-state power dissipation for the 1N5921B and how does it derate with temperature?

The 1N5921B supports 3 W steady-state power dissipation at lead temperature (T_L) = 75°C with 3/8″ lead length; above 75°C, it derates linearly at 24 mW/°C. At ambient temperature (T_A) = 50°C, its rated dissipation drops to 1 W with 6.67 mW/°C derating-values strictly defined in the Maximum Ratings table on page 1 of the datasheet.

Does the 1N5921B have a specified temperature coefficient, and what is its impact at 6.8 V?

Yes-the 1N5921B exhibits a near-zero temperature coefficient around 6.8 V, as shown in Figure 5 of the datasheet, where the typical coefficient is approximately 0 mV/°C. This minimizes V_Z drift across −65°C to +200°C operating range, making the 1N5921B especially suitable for precision reference applications where thermal stability is critical.

What is the surge power rating of the 1N5921B and under what conditions is it validated?

The 1N5921B is rated for 98 W nonrepetitive surge power at 1 ms pulse width, as specified in Figure 3 of the datasheet and confirmed in the Features section. This rating applies to rectangular waveform pulses with T_J = 25°C prior to initial pulse and is validated under strict test conditions-not extrapolated from thermal resistance curves.

Is the 1N5921B RoHS-compliant and what does the "G" suffix indicate?

Yes-the "G" suffix in 1N5921B, G explicitly denotes a Pb-free (RoHS-compliant) package per onsemi's ordering information on page 1. The device meets JEDEC J-STD-020 moisture sensitivity level 1 and is qualified for lead-free reflow and wave soldering up to 260°C, as documented in the Mechanical Characteristics section.

1N5921B Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: DO-204AL, DO-41, Axial

Packaging:: Bulk

Product Status:: Obsolete

Voltage - Zener (Nom) (Vz):: 6.8 V

Tolerance:: ±5%

Power - Max:: 3 W

Impedance (Max) (Zzt):: 2.5 Ohms

Current - Reverse Leakage @ Vr:: 5 µA @ 5.2 V

Voltage - Forward (Vf) (Max) @ If:: 1.5 V @ 200 mA

Operating Temperature:: -65°C ~ 200°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: Axial

1N5921B FAQ

1.How can I place an order for 1N5921B through Aetrix?

Please submit a Request for Quotation (RFQ) for 1N5921B 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 1N5921B reliable?

The price and inventory of 1N5921B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N5921B is usually 5 days.

3.What payment methods are accepted for 1N5921B?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N5921B transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 1N5921B?

1N5921B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 1N5921B 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 1N5921B?

For technical support, including 1N5921B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N5921B requirements.

6.How does Aetrix verify that 1N5921B is sourced from the original manufacturer or authorized distributors?

All 1N5921B 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 1N5921B meets industry standards.

7.What is the process for return or replacement of 1N5921B?

All 1N5921B units undergo pre-shipment inspection (PSI). If there is an issue with 1N5921B, 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 1N5921B part is unused and in its original packaging.

Return procedure for 1N5921B:

1.Submit a request within 90 days.

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

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