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onsemi BZX85C18-T50A
- Part No.:
- BZX85C18-T50A
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-204AL, DO-41, Axial
- Datasheet:
-
BZX85C18-T50A.pdf
- Description:
- DIODE ZENER 18V 1W DO41
- Quantity:
- Payment:
- Shipping:
Inventory:6,334
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Product details
Overview
BZX85C18-T50A from onsemi is a 18 V ±5% Zener diode in DO-41 glass package, rated for 1.0 W power dissipation at 25°C, with 15 Ω zener impedance at 20 mA test current and 0.5 μA maximum leakage at 14 V reverse voltage. It provides stable voltage reference in low-power regulator and protection circuits.
For engineers reviewing the BZX85C18-T50A datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage tolerance, thermal derating (6.67 mW/°C above 50°C), junction temperature range (–65°C to +200°C), and DO-41 mechanical compatibility with axial leaded PCB layouts.
Technical Context
The BZX85C18-T50A operates as a silicon planar Zener diode optimized for voltage regulation and overvoltage clamping. Its 18 V nominal breakdown voltage is specified at IZ = 20 mA with ±5% tolerance, and it exhibits 15 Ω dynamic impedance (ZZ) under that condition.
It features a glass-passivated DO-41 package with cathode band marking, supports continuous operation up to +200°C junction temperature, and complies with JEDEC DO-204AL mechanical standards. Forward voltage is ≤1.2 V at 200 mA, confirming standard PN junction behavior.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 16.8 V min / 19.1 V max at IZ = 20 mA - defines usable regulation window for precision reference designs |
| Power Dissipation (PD) | 1.0 W @ TA = 25°C - sets maximum continuous DC power handling without heatsinking |
| Zener Impedance (ZZ) | 15 Ω @ IZ = 20 mA - determines output voltage stability under load variation |
| Leakage Current (IR) | 0.5 μA max @ VR = 14 V - ensures minimal standby current in high-impedance bias networks |
| Operating Temperature | –65°C to +200°C - enables use in automotive under-hood and industrial high-temp environments |
| Thermal Derating | 6.67 mW/°C above 50°C - requires linear power reduction above ambient threshold for reliability |
| Forward Voltage (VF) | ≤1.2 V @ IF = 200 mA - confirms low-loss forward conduction for bidirectional clamp configurations |
Pinout & Package
DO-41 glass axial package with cathode identified by a single color band on the body. Leads are tinned copper-clad steel, compatible with wave and hand soldering per J-STD-020.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / Zener cathode reference ground | Connected to lower-potential node in shunt regulation; reverse-biased during Zener operation |
| Cathode | Zener breakdown terminal / voltage reference output | Marked with color band; connected to regulated rail; sinks current to maintain VZ |
Key Features
| Feature | Design Value |
|---|---|
| ±5% Zener voltage tolerance | Enables predictable regulation without post-production trimming in cost-sensitive consumer power supplies |
| 1.0 W power rating | Supports higher-current shunt regulation than 400 mW devices, reducing need for external pass transistors |
| DO-41 glass package | Provides hermetic sealing and thermal stability superior to plastic packages in humid or high-reliability environments |
| Low 0.5 μA leakage at 14 V | Minimizes quiescent current draw in battery-powered voltage monitor circuits |
| JEDEC DO-204AL compliance | Ensures mechanical interchangeability with legacy DO-41 footprints and automated assembly tooling |
Applications
| Overvoltage Protection Clamp | Low-Power Voltage Reference |
|---|---|
Use Scenario: Clamping transient surges on 15 V logic supply rails in industrial PLC I/O modules. IC Role / Device Role / Timing Role: Shunt clamping device absorbing ESD and inductive kick energy above 18 V threshold. Use Value: Prevents damage to downstream 16 V-rated interface ICs using only passive components and no active control circuitry. |
Use Scenario: Providing stable 18 V reference for ADC biasing in portable medical sensor front-ends. IC Role / Device Role / Timing Role: Precision voltage source for analog signal conditioning circuitry requiring <1% drift over temperature. Use Value: Delivers ±5% initial accuracy and <0.5 μA leakage to extend battery life while maintaining measurement linearity. |
| DC Power Supply Regulation | Signal Level Translation |
Use Scenario: Regulating unregulated 24 V wall adapter output to fixed 18 V for op-amp biasing in audio preamps. IC Role / Device Role / Timing Role: Shunt regulator maintaining constant voltage across load despite input ripple and load current variation. Use Value: Achieves <50 mV line regulation with 15 Ω ZZ, eliminating need for three-terminal regulators in space-constrained designs. |
Use Scenario: Translating 3.3 V microcontroller GPIO signals to 18 V logic levels for driving external relays. IC Role / Device Role / Timing Role: Bidirectional level-shifter using forward conduction (≤1.2 V) and reverse Zener breakdown (18 V). Use Value: Enables simple, low-cost interface between low-voltage digital controllers and high-voltage actuators without dedicated level-shift ICs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4746A | 18 V ±5%, 1.0 W, DO-41, but ZZ = 20 Ω @ 21 mA - higher impedance than BZX85C18-T50A's 15 Ω | Slightly reduced regulation stiffness under dynamic load; same thermal envelope and footprint | Acceptable where tighter voltage stability is not required and legacy 1N47xx sourcing is preferred |
| MMSZ5246B | 18 V ±5%, 500 mW, SOD-123 surface-mount package - half the power rating and different mounting | Not suitable for >500 mW continuous dissipation; requires PCB rework for SMT vs. through-hole | Preferred for space-constrained PCBs where power demand stays below 0.5 W and reflow assembly is used |
Compared with 1N4746A and MMSZ5246B, the BZX85C18-T50A delivers lower zener impedance for improved regulation accuracy and full 1.0 W capability in a proven through-hole package-making it optimal for robust, medium-power shunt regulation where thermal margin and mechanical reliability are prioritized.
Availability
BZX85C18-T50A is available at Aetrix Electronics and suitable for industrial power supplies, automotive body electronics, and medical sensor modules requiring stable component supply with long-term manufacturability.
Supply support for BZX85C18-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, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The BZX85C18-T50A belongs to the BZX85C series of general-purpose Zener diodes designed for reliable voltage regulation and transient suppression in cost-sensitive, high-volume applications across industrial and automotive sectors.
FAQ
What is the Zener voltage tolerance for BZX85C18-T50A?
The BZX85C18-T50A has a Zener voltage tolerance of ±5%, meaning its breakdown voltage is guaranteed between 16.8 V and 19.1 V when tested at 20 mA. This tolerance is measured under thermal equilibrium conditions at 30°C lead temperature, per the official onsemi datasheet revision 2 (October 2017). The BZX85C18-T50A achieves this specification using a tightly controlled diffusion process in its silicon die.
Can BZX85C18-T50A be used in surface-mount designs?
No - the BZX85C18-T50A uses a DO-41 axial glass package with leads designed for through-hole mounting. It is not compatible with SMT reflow processes due to thermal mass and glass-body fragility. For surface-mount alternatives, consider the MMSZ5246B (SOD-123, 500 mW) or NZ9F18ST5G (SOD-923, 200 mW), but note their lower power ratings and different thermal profiles compared to the BZX85C18-T50A.
What is the maximum allowable junction temperature for BZX85C18-T50A?
The BZX85C18-T50A has a maximum junction temperature (TJ) of +200°C and a storage temperature range of –65°C to +200°C. This wide range allows operation in under-hood automotive environments and high-temperature industrial enclosures. Derating begins at 50°C ambient, with power dissipation reduced by 6.67 mW per °C above that point - a critical design constraint for sustained BZX85C18-T50A performance.
How does the zener impedance of BZX85C18-T50A affect regulation performance?
The BZX85C18-T50A specifies 15 Ω zener impedance (ZZ) at IZ = 20 mA, indicating how much its output voltage changes per mA of current variation. Lower ZZ means tighter regulation - for example, a 10 mA load shift causes only ~150 mV deviation in BZX85C18-T50A's output, versus ~200 mV for the 1N4746A (20 Ω). This makes the BZX85C18-T50A preferable in applications demanding stable reference voltage under varying load.
Is BZX85C18-T50A RoHS compliant and lead-free?
Yes - the BZX85C18-T50A is RoHS compliant and lead-free, meeting EU Directive 2011/65/EU and subsequent amendments. onsemi confirms this status in its official product change notifications and packaging data sheets. The DO-41 glass package contains no lead-based solder or plating, and all materials comply with JEDEC J-STD-609 moisture sensitivity and halogen-free requirements applicable to the BZX85C18-T50A.
BZX85C18-T50A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- DO-204AL, DO-41, Axial
- Packaging:
- Cut Tape (CT)
- Product Status:
- Obsolete
- Voltage - Zener (Nom) (Vz):
- 18 V
- Tolerance:
- ±6%
- Power - Max:
- 1 W
- Impedance (Max) (Zzt):
- 20 Ohms
- Current - Reverse Leakage @ Vr:
- 500 nA @ 12.5 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
BZX85C18-T50A FAQ
1.How can I place an order for BZX85C18-T50A through Aetrix?
Please submit a Request for Quotation (RFQ) for BZX85C18-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 BZX85C18-T50A reliable?
The price and inventory of BZX85C18-T50A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX85C18-T50A is usually 5 days.
3.What payment methods are accepted for BZX85C18-T50A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX85C18-T50A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BZX85C18-T50A?
BZX85C18-T50A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BZX85C18-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 BZX85C18-T50A?
For technical support, including BZX85C18-T50A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX85C18-T50A requirements.
6.How does Aetrix verify that BZX85C18-T50A is sourced from the original manufacturer or authorized distributors?
All BZX85C18-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 BZX85C18-T50A meets industry standards.
7.What is the process for return or replacement of BZX85C18-T50A?
All BZX85C18-T50A units undergo pre-shipment inspection (PSI). If there is an issue with BZX85C18-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 BZX85C18-T50A part is unused and in its original packaging.
Return procedure for BZX85C18-T50A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
BZX85C18-T50A Tags
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MMBZ5240B-7-F
Diodes Incorporated
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BZT52C5V6T-7
Diodes Incorporated
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MMSZ5231B-7-F
Diodes Incorporated
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BZT52C15-7-F
Diodes Incorporated
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BZX84C3V3LT1G
onsemi
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MMSZ5245BS-7-F
Diodes Incorporated
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MMSZ4682T1G
onsemi
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BZT52C15S-7-F
Diodes Incorporated
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MM5Z5V1ST1G
onsemi
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SMAJ4744A-TP
Micro Commercial Co
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BZT52C3V6LP-7
Diodes Incorporated
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SMAZ12-13-F
Diodes Incorporated
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