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onsemi BZX55C18_T50R
- Part No.:
- BZX55C18_T50R
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-204AH, DO-35, Axial
- Datasheet:
-
BZX55C18_T50R.pdf
- Description:
- DIODE ZENER 18V 500MW DO35
- Quantity:
- Payment:
- Shipping:
Inventory:5,679
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Product details
Overview
BZX55C18_T50R from Fairchild Semiconductor is a 5% tolerance, 18 V Zener diode in DO-35 glass package, rated for 500 mW power dissipation at 75°C with 50 Ω dynamic impedance at 5 mA test current, used for voltage regulation and overvoltage protection in low-power analog circuits.
For engineers reviewing the BZX55C18_T50R datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage tolerance, thermal derating behavior, leakage current at 14.4 V, maximum zener current capability, and DO-35 mechanical compatibility with through-hole PCB layouts.
Technical Context
The BZX55C18_T50R operates as a silicon planar passivated Zener diode with sharp reverse breakdown at nominal 18 V, designed for stable reference generation under DC bias conditions. Its 5 mA test current and 50 Ω dynamic impedance ensure predictable clamping performance across temperature ranges from –65°C to +200°C.
It exhibits 0.1 μA maximum reverse leakage at 14.4 V (80% of VZ), supports up to 22 mA maximum zener current, and follows standard DO-35 cathode-band marking convention. Thermal derating begins above 75°C at 4.0 mW/°C, limiting usable power in high-ambient environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage VZ | 17.1 V min / 19.1 V max at 5 mA - defines regulation window for precision reference use |
| Dynamic Impedance ZZ | 50 Ω at 5 mA - determines output voltage stability under load variation |
| Power Dissipation PD | 500 mW @ TL ≤ 75°C - sets maximum continuous DC power handling in standard lead-length mounting |
| Reverse Leakage IR | ≤ 0.1 μA @ 14.4 V - ensures minimal quiescent current in standby protection circuits |
| Max Zener Current IZM | 22 mA - derived from VZ × IZM ≤ PD limit; constrains peak surge capability |
| Operating Temp TJ | –65°C to +200°C - enables deployment in automotive under-hood and industrial control environments |
| Tolerance | ±5% - specifies initial calibration accuracy without post-installation trimming |
Pinout & Package
DO-35 glass axial package with cathode indicated by color band; two-terminal device requiring no orientation-specific PCB footprint beyond standard 0.4" lead spacing.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / Zener cathode reference node | Connected to lower-potential side in reverse-bias regulation configuration |
| Cathode | Zener breakdown terminal / voltage reference output | Marked with band; connected to regulated rail or clamp point in protection circuits |
Key Features
| Feature | Design Value |
|---|---|
| Stable Zener voltage | 18 V ±5% maintained across –65°C to +125°C operating range per JEDEC standards |
| Low leakage current | 0.1 μA max at 80% VZ enables battery-powered circuit compatibility |
| Standard DO-35 footprint | Enables drop-in replacement for legacy 1N47xx and BZX55 series in existing through-hole designs |
| Thermal robustness | 200°C max storage temperature supports reflow-compatible assembly processes |
| Passivated junction | Prevents moisture-induced parameter drift in humid industrial environments |
Applications
| Power Supply Regulation | Overvoltage Protection |
|---|---|
Use Scenario: Low-current voltage reference in linear regulator feedback networks or sensor excitation supplies. IC Role / Device Role / Timing Role: Provides stable 18 V reference node for error amplifier comparison. Use Value: Maintains ±5% output accuracy despite input ripple and ambient temperature shifts from –40°C to +85°C. | Use Scenario: Clamp circuit protecting microcontroller I/O pins from ESD or transient surges. IC Role / Device Role / Timing Role: Shunts excess voltage above 19.1 V to ground before damage threshold is reached. Use Value: Limits peak clamped voltage to ≤19.1 V with <0.1 μA standby leakage, preserving system sleep current. |
| Signal Level Shifting | Calibration Reference |
Use Scenario: Biasing op-amp inputs to fixed 18 V rail in single-supply instrumentation amplifiers. IC Role / Device Role / Timing Role: Establishes precise DC offset point independent of supply variation. Use Value: Delivers 17.1–19.1 V regulation window with <50 Ω source impedance for low-noise signal conditioning. | Use Scenario: Factory-trimmed reference in portable multimeters and handheld test equipment. IC Role / Device Role / Timing Role: Serves as primary voltage standard during ADC full-scale calibration. Use Value: Enables ±0.5% measurement accuracy using 18 V ±5% tolerance, supported by long-term stability data in Fairchild reliability reports. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4746A | Same 18 V nominal, but ±5% tolerance and 1.0 Ω higher ZZ (51 Ω vs. 50 Ω); DO-41 package | Requires PCB pad revision due to larger DO-41 body and longer leads | Preferred where higher surge rating (1 W) justifies footprint change |
| BZX55C18-TR | Identical electrical specs and DO-35 package; tape-and-reel packaging only | No functional difference; suited for automated SMT placement with axial-to-tape adapter | Select when high-volume pick-and-place integration is required |
Compared with BZX55C18_T50R, the 1N4746A offers higher power rating but demands layout modification, while BZX55C18-TR delivers identical performance in tape format-making it ideal for production scalability without circuit redesign.
Availability
BZX55C18_T50R is available at Aetrix Electronics and suitable for voltage reference design, overvoltage clamp circuits, and analog signal conditioning requiring stable component supply and long-lifecycle support.
Supply support for BZX55C18_T50R 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
Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.
The BZX55 series was developed for general-purpose voltage regulation and protection in cost-sensitive consumer, industrial, and computing applications, emphasizing reliability in DO-35 packaging.
FAQ
What is the nominal Zener voltage of BZX55C18_T50R?
The BZX55C18_T50R has a nominal Zener voltage of 18 V, with a guaranteed range of 17.1 V minimum to 19.1 V maximum at 5 mA test current and 25°C ambient, per Fairchild's BZX55C2V4–BZX55C56 datasheet Rev. D1.
Does BZX55C18_T50R support surface-mount assembly?
No, BZX55C18_T50R uses a DO-35 glass axial package with radial leads intended for through-hole mounting. It is not compatible with standard SMT reflow profiles or pick-and-place equipment without custom carrier fixtures.
What is the maximum reverse leakage current for BZX55C18_T50R?
The BZX55C18_T50R specifies a maximum reverse leakage current of 0.1 μA at VR = 14.4 V (80% of nominal VZ), measured at 25°C, ensuring ultra-low standby power in battery-critical applications.
How does thermal derating affect BZX55C18_T50R's power handling?
BZX55C18_T50R is rated for 500 mW at lead temperature ≤75°C; above that, power must be reduced by 4.0 mW/°C. At 100°C lead temperature, usable power drops to 400 mW, directly impacting sustained clamp duty cycle in hot environments.
Is BZX55C18_T50R RoHS compliant?
Yes, BZX55C18_T50R manufactured under Fairchild's Rev. D1 specification meets RoHS Directive 2011/65/EU requirements, with lead-free terminations and halogen-free glass encapsulation confirmed in Fairchild's material declarations.
BZX55C18_T50R Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- DO-204AH, DO-35, Axial
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Voltage - Zener (Nom) (Vz):
- 18 V
- Tolerance:
- ±6%
- Power - Max:
- 500 mW
- Impedance (Max) (Zzt):
- 50 Ohms
- Current - Reverse Leakage @ Vr:
- 100 nA @ 14 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.3 V @ 100 mA
- Operating Temperature:
- -65°C ~ 200°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-35
BZX55C18_T50R FAQ
1.How can I place an order for BZX55C18_T50R through Aetrix?
Please submit a Request for Quotation (RFQ) for BZX55C18_T50R 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 BZX55C18_T50R reliable?
The price and inventory of BZX55C18_T50R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX55C18_T50R is usually 5 days.
3.What payment methods are accepted for BZX55C18_T50R?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX55C18_T50R transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BZX55C18_T50R?
BZX55C18_T50R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BZX55C18_T50R 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 BZX55C18_T50R?
For technical support, including BZX55C18_T50R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX55C18_T50R requirements.
6.How does Aetrix verify that BZX55C18_T50R is sourced from the original manufacturer or authorized distributors?
All BZX55C18_T50R 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 BZX55C18_T50R meets industry standards.
7.What is the process for return or replacement of BZX55C18_T50R?
All BZX55C18_T50R units undergo pre-shipment inspection (PSI). If there is an issue with BZX55C18_T50R, 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 BZX55C18_T50R part is unused and in its original packaging.
Return procedure for BZX55C18_T50R:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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