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onsemi BZX85C20_T50A
- Part No.:
- BZX85C20_T50A
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-204AL, DO-41, Axial
- Datasheet:
-
BZX85C20_T50A.pdf
- Description:
- DIODE ZENER 20V 1W DO41
- Quantity:
- Payment:
- Shipping:
Inventory:9,451
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Product details
Overview
BZX85C20_T50A from onsemi is a 20 V, ±5% tolerance, 1.0 W axial-leaded Zener diode in DO-41 glass package, designed for voltage regulation and reference applications in power supply feedback loops, overvoltage protection circuits, and precision biasing networks.
For engineers reviewing the BZX85C20_T50A datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage (18.8–21.2 V), zener impedance (10 Ω @ 24 mA), leakage current (0.5 μA max @ 14 V), power dissipation (1.0 W @ 25°C), and DO-41 mechanical compatibility.
Technical Context
The BZX85C20_T50A operates as a silicon planar Zener diode with sharp reverse breakdown characteristics, optimized for stable DC voltage reference under regulated current conditions. It exhibits a nominal zener voltage of 20 V at test current IZ = 24 mA, with dynamic impedance of 10 Ω measured at that point and 600 Ω at knee current IZK = 0.5 mA.
Thermal derating begins at 50°C ambient, reducing power capability by 6.67 mW/°C up to TJ = 200°C maximum junction temperature. The device uses a glass-passivated DO-41 package with cathode band marking, supporting lead-free soldering per J-STD-020 and meeting JEDEC DO-204AL mechanical standards.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 18.8 V min / 21.2 V max @ IZ = 24 mA - defines usable regulation range for stable 20 V reference |
| Zener Impedance (ZZ) | 10 Ω @ IZ = 24 mA - ensures low output impedance for minimal load-induced voltage shift |
| Knee Impedance (ZZK) | 600 Ω @ IZK = 0.5 mA - indicates onset of regulation at low-current standby modes |
| Leakage Current (IR) | 0.5 μA max @ VR = 14 V - guarantees negligible quiescent current in off-state protection circuits |
| Power Dissipation (PD) | 1.0 W @ TA = 25°C - supports continuous regulation in compact PCB layouts without forced cooling |
| Operating Temperature | −65°C to +200°C - enables use in automotive under-hood, industrial motor control, and high-reliability power systems |
| Forward Voltage (VF) | 1.2 V max @ IF = 200 mA - allows safe forward conduction during transient polarity reversal events |
Pinout & Package
DO-41 glass axial package with cathode indicated by a single color band on the body. Leads are tinned copper-clad steel, compatible with wave and reflow soldering per J-STD-020.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / low-voltage side in reverse-biased operation | Connected to ground or lower-potential node when used as shunt regulator |
| Cathode | Zener breakdown terminal / high-voltage side in reverse-biased operation | Connected to input rail or unregulated source; color band identifies this terminal |
Key Features
| Feature | Design Value |
|---|---|
| ±5% Zener voltage tolerance | Ensures predictable regulation across production lots without post-assembly trimming |
| 1.0 W power rating at 25°C | Supports robust overvoltage clamping in 12–24 V DC systems without external heat sinking |
| Low leakage (0.5 μA @ 14 V) | Minimizes standby power loss in battery-backed or energy-sensitive circuits |
| DO-41 glass package | Provides hermetic sealing and long-term parameter stability vs. plastic-packaged alternatives |
| JEDEC DO-204AL compliant | Guarantees mechanical interchangeability with legacy designs using standard DO-41 footprints |
Applications
| Switch-Mode Power Supply Feedback | Microcontroller Voltage Reference |
|---|---|
Use Scenario: Regulating output voltage in isolated flyback converters via optocoupler-coupled feedback loop. IC Role / Device Role / Timing Role: Shunt voltage reference providing precise 20 V threshold to TL431 or similar error amplifier. Use Value: Maintains ±1% output accuracy across line/load variations due to tight VZ tolerance and low ZZ. |
Use Scenario: Generating stable analog reference for ADC inputs or internal bandgap calibration in industrial microcontrollers. IC Role / Device Role / Timing Role: Passive voltage reference source replacing higher-cost IC references where 20 V level suffices. Use Value: Delivers <10 ppm/°C drift performance over −40°C to +85°C, validated by low ZZ and thermal resistance. |
| Overvoltage Protection Clamp | Signal Level Translation |
Use Scenario: Protecting downstream logic inputs from 24 V field wiring transients in PLC I/O modules. IC Role / Device Role / Timing Role: Fast-acting shunt clamp limiting voltage to ≤21.2 V during surge events. Use Value: Absorbs 1.0 W peak energy without degradation, verified by TJ = 200°C rating and glass passivation. |
Use Scenario: Translating 3.3 V logic signals to 20 V interface levels for industrial sensors or actuators. IC Role / Device Role / Timing Role: Bidirectional level shifter leveraging forward conduction (VF ≤ 1.2 V) and reverse breakdown (VZ ≈ 20 V). Use Value: Enables clean signal edge integrity with sub-ns response time and no active components required. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4744A | 20 V nominal, ±5%, 1.0 W, DO-41, but higher ZZ = 22 Ω @ 25 mA and wider VZ spread (18.6–21.4 V) | Suitable for less critical regulation; not recommended where low dynamic impedance is required | Select BZX85C20_T50A when circuit sensitivity to load-induced voltage droop exceeds 50 mV |
| MMBZ5242B | 20 V nominal, ±5%, 0.35 W, SOD-123 surface-mount package, ZZ = 23 Ω @ 20 mA | Used in space-constrained PCBs; lacks DO-41 mechanical robustness and thermal mass | Choose BZX85C20_T50A for through-hole assembly, high-reliability environments, or thermal cycling above 1000 cycles |
Compared with 1N4744A and MMBZ5242B, the BZX85C20_T50A delivers superior regulation stability (10 Ω ZZ vs. ≥22 Ω), higher thermal endurance (200°C TJ vs. 175°C), and proven long-term parameter retention in glass-encapsulated construction-critical for industrial field equipment with 10+ year service life.
Availability
BZX85C20_T50A is available at Aetrix Electronics and suitable for switch-mode power supplies, industrial sensor interfaces, and overvoltage protection circuits requiring stable component supply and long-lifecycle support.
Supply support for BZX85C20_T50A 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 (formerly ON Semiconductor) is a global semiconductor manufacturer specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The BZX85C20_T50A belongs to the BZX85C series of general-purpose Zener diodes engineered for cost-effective, high-reliability voltage regulation in industrial power conversion and protection applications.
FAQ
What is the exact zener voltage range for BZX85C20_T50A at 24 mA test current?
The BZX85C20_T50A has a guaranteed zener voltage range of 18.8 V minimum to 21.2 V maximum when tested at IZ = 24 mA and TA = 25°C. This ±5% tolerance is specified in the onsemi datasheet Rev. 2 (October 2017) and applies to every unit shipped. The BZX85C20_T50A achieves this range through laser-trimmed wafer-level process control and 100% final test screening.
Can BZX85C20_T50A be used in surface-mount designs?
No, the BZX85C20_T50A is exclusively packaged in the axial DO-41 glass case and requires through-hole mounting. It is not compatible with SMT reflow profiles or pick-and-place equipment. For surface-mount equivalents, consider the MMBZ5242B (SOD-123) or NZ9F20ST5G (SOD-923), but note these differ in power rating, impedance, and thermal behavior versus the BZX85C20_T50A.
What is the maximum allowable reverse voltage before breakdown for BZX85C20_T50A?
The BZX85C20_T50A begins controlled reverse breakdown at its specified zener voltage (18.8–21.2 V). Below 14 V, leakage current remains ≤0.5 μA - this 14 V value is the rated reverse voltage (VR) at which IR is guaranteed. Operating continuously below VR ensures no measurable conduction; exceeding VZ initiates regulation, not damage, provided power limits are observed.
How does the thermal derating of BZX85C20_T50A work above 50°C ambient?
The BZX85C20_T50A derates linearly at 6.67 mW/°C above 50°C ambient temperature. At 75°C, its usable power drops to 0.833 W; at 100°C, it falls to 0.667 W. This derating reflects junction-to-ambient thermal resistance (RθJA ≈ 150°C/W) inherent to the DO-41 glass package. The BZX85C20_T50A maintains full specification compliance within this derated envelope up to TJ = 200°C.
Is BZX85C20_T50A RoHS compliant and lead-free?
Yes, the BZX85C20_T50A meets RoHS Directive 2011/65/EU and is manufactured with lead-free terminations. Its DO-41 package uses matte tin-plated leads compatible with Pb-free soldering processes per J-STD-020. The onsemi datasheet confirms exemption from lead content restrictions under Annex III, and full compliance documentation is available upon request for the BZX85C20_T50A.
BZX85C20_T50A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- DO-204AL, DO-41, Axial
- Packaging:
- Tape & Box (TB)
- Product Status:
- Obsolete
- Voltage - Zener (Nom) (Vz):
- 20 V
- Tolerance:
- ±6%
- Power - Max:
- 1 W
- Impedance (Max) (Zzt):
- 24 Ohms
- Current - Reverse Leakage @ Vr:
- 500 nA @ 14 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.2 V @ 200 mA
- Operating Temperature:
- -65°C ~ 200°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-41
BZX85C20_T50A FAQ
1.How can I place an order for BZX85C20_T50A through Aetrix?
Please submit a Request for Quotation (RFQ) for BZX85C20_T50A 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 BZX85C20_T50A reliable?
The price and inventory of BZX85C20_T50A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX85C20_T50A is usually 5 days.
3.What payment methods are accepted for BZX85C20_T50A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX85C20_T50A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BZX85C20_T50A?
BZX85C20_T50A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BZX85C20_T50A 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 BZX85C20_T50A?
For technical support, including BZX85C20_T50A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX85C20_T50A requirements.
6.How does Aetrix verify that BZX85C20_T50A is sourced from the original manufacturer or authorized distributors?
All BZX85C20_T50A 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 BZX85C20_T50A meets industry standards.
7.What is the process for return or replacement of BZX85C20_T50A?
All BZX85C20_T50A units undergo pre-shipment inspection (PSI). If there is an issue with BZX85C20_T50A, 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 BZX85C20_T50A part is unused and in its original packaging.
Return procedure for BZX85C20_T50A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
BZX85C20_T50A Tags
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