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onsemi BZX79C33-T50A
- Part No.:
- BZX79C33-T50A
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-204AH, DO-35, Axial
- Datasheet:
-
BZX79C33-T50A.pdf
- Description:
- DIODE ZENER 33V 500MW DO35
- Quantity:
- Payment:
- Shipping:
Inventory:75,000
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Product details
Overview
BZX79C33-T50A from onsemi is a 33 V ±5% tolerance, 500 mW axial-lead Zener diode in DO-204AH (Case 017AG) glass package, rated for 5 mA test current, 100 Ω dynamic impedance, and −3.5 mV/°C temperature coefficient, used for precision voltage regulation and overvoltage protection in low-power analog circuits.
For engineers reviewing the BZX79C33-T50A datasheet, pinout, applications, or equivalent options, key selection considerations include zener voltage tolerance, thermal coefficient, power derating above 75°C, junction temperature range (−65°C to +200°C), and axial lead mechanical compatibility with through-hole PCB assembly.
Technical Context
The BZX79C33-T50A operates as a silicon planar Zener diode with controlled reverse breakdown at 33 V nominal, specified under thermal equilibrium at TL = 30°C ±1°C with 3/8″ lead length. Its −3.5 mV/°C temperature coefficient ensures predictable drift across industrial temperature ranges.
Designed for stable DC reference and clamping, it exhibits 100 Ω dynamic impedance at IZ = 5 mA and ≤100 nA leakage current at VR = 25.5 V (0.75 × VZ), with forward voltage ≤1.2 V at IF = 200 mA - confirming suitability for bidirectional protection and dual-polarity biasing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 31.35 V to 34.65 V @ IZ = 5 mA - defines regulated output range for reference and clamp circuits |
| Power Dissipation (PD) | 500 mW @ TL ≤ 75°C - sets maximum continuous power handling before thermal derating begins |
| Dynamic Impedance (ZZ) | 100 Ω max @ IZ = 5 mA - determines regulation stiffness and output voltage variation under load changes |
| Temperature Coefficient (TC) | −3.5 mV/°C - quantifies voltage drift per degree Celsius, critical for temperature-stable references |
| Leakage Current (IR) | ≤100 nA @ VR = 25.5 V - ensures minimal error current in high-impedance bias networks |
| Junction Temp Range | −65°C to +200°C - supports operation in harsh environments including automotive under-hood and industrial controls |
Pinout & Package
Package: DO-204AH (Case 017AG), hermetically sealed glass axial-lead package, 4.56 mm body length, 1.91 mm diameter, 0.137 g weight, JEDEC-compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (A) | Forward conduction terminal / cathode-side reference ground | Connected to circuit ground or lower potential node when used in reverse-biased regulation |
| Cathode (K) | Zener breakdown terminal / voltage reference output | Provides stabilized 33 V output relative to anode; polarity must be observed for correct clamping direction |
Key Features
| Feature | Design Value |
|---|---|
| ±5% Zener voltage tolerance | Enables tight regulation without external trimming in cost-sensitive voltage reference designs |
| −3.5 mV/°C TC | Minimizes thermal drift in unregulated power supplies and sensor excitation circuits |
| 100 Ω dynamic impedance | Maintains <1% output deviation under ±1 mA load variation at nominal current |
| Hermetic glass package | Ensures long-term reliability and moisture resistance in humid or high-reliability applications |
| DO-204AH mechanical standard | Guarantees compatibility with legacy axial-lead insertion equipment and board layouts |
Applications
| Power Supply Reference | Sensor Excitation |
|---|---|
Use Scenario: Providing stable 33 V bias for op-amp input stages and ADC reference dividers in isolated DC-DC converters. IC Role / Device Role / Timing Role: Voltage reference diode establishing precise DC operating point for analog signal conditioning. Use Value: Maintains ±0.5% output stability over −40°C to +85°C ambient due to matched TC and low ZZ. |
Use Scenario: Supplying constant-current excitation to RTD or strain gauge bridges in industrial transmitters. IC Role / Device Role / Timing Role: Zener-regulated current source element via series resistor, delivering stable 33 V compliance voltage. Use Value: Enables <0.1% full-scale error contribution from reference drift across temperature cycles. |
| Overvoltage Clamp | Microcontroller I/O Protection |
Use Scenario: Clamping transient surges on 24 V industrial control lines to protect downstream logic inputs. IC Role / Device Role / Timing Role: Reverse-biased shunt protector diverting excess energy to ground during ESD or inductive kick events. Use Value: Responds within nanoseconds with <100 nA leakage below 25.5 V, minimizing standby power loss. |
Use Scenario: Protecting 3.3 V or 5 V MCU GPIO pins from accidental 24 V miswiring or backfeed. IC Role / Device Role / Timing Role: Bidirectional clamp (forward + reverse) limiting pin voltage to safe levels using combined VF and VZ. Use Value: Leverages 1.2 V forward drop and 33 V reverse breakdown to confine pin voltage between −1.2 V and +33 V. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4747A | 33 V nominal, ±5%, 1 W rating, DO-41 package, +3.5 mV/°C TC (opposite sign) | Higher power handling but larger footprint and positive TC limits temp-stable reference use | Select when higher surge energy absorption is required and thermal drift direction is acceptable |
| BZX55C33 | 33 V nominal, ±5%, 500 mW, DO-35 package, −3.5 mV/°C TC, but 150 Ω ZZ @ 5 mA | Same regulation voltage and TC, but higher dynamic impedance reduces regulation accuracy | Choose only if DO-35 footprint constraints prohibit DO-204AH and 50 Ω extra impedance is tolerable |
Compared with 1N4747A and BZX55C33, the BZX79C33-T50A offers identical voltage tolerance and TC sign but superior regulation stiffness (100 Ω vs. 150–200 Ω) and axial-lead compatibility with legacy DO-204AH tooling - making it optimal for space-constrained, temperature-critical reference designs requiring proven manufacturability.
Availability
BZX79C33-T50A is available at Aetrix Electronics and suitable for industrial sensor interfaces, programmable logic controller (PLC) input protection, and analog front-end voltage reference applications requiring stable component supply and long-lifecycle support.
Supply support for BZX79C33-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 supplier specializing in energy-efficient power, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The BZX79C33-T50A belongs to the BZX79C family of general-purpose Zener diodes designed for cost-effective, reliable voltage regulation and transient suppression in high-volume industrial and commercial electronics.
FAQ
What is the exact Zener voltage range for BZX79C33-T50A at 5 mA test current?
The BZX79C33-T50A has a guaranteed Zener voltage range of 31.35 V to 34.65 V (±5%) when measured at IZ = 5 mA, TL = 30°C ±1°C, and 3/8″ lead length - matching the specification in the official onsemi datasheet Rev. 5. This tolerance band ensures predictable performance in production voltage reference circuits without calibration.
Does BZX79C33-T50A have a positive or negative temperature coefficient?
The BZX79C33-T50A has a temperature coefficient of −3.5 mV/°C, meaning its Zener voltage decreases by 3.5 mV per degree Celsius rise in junction temperature. This negative TC is typical for Zener diodes in the 30–40 V range and must be accounted for in precision reference designs where thermal gradients exist.
What is the maximum allowable power dissipation for BZX79C33-T50A at 100°C ambient?
At ambient temperatures above 75°C, the BZX79C33-T50A must be derated at 4.0 mW/°C. At 100°C ambient, its maximum power dissipation is reduced to 400 mW (500 mW − [4.0 mW/°C × 25°C]). This derating ensures safe junction temperature operation up to +200°C.
Is BZX79C33-T50A compatible with automated through-hole assembly equipment?
Yes, the BZX79C33-T50A uses the DO-204AH (Case 017AG) axial-lead package with standardized dimensions - 4.56 mm body length, 1.91 mm diameter, and 25.40 mm minimum lead spacing - ensuring compatibility with industry-standard axial insertion machines and wave soldering processes.
Can BZX79C33-T50A be used for bidirectional ESD protection?
Yes, the BZX79C33-T50A provides bidirectional clamping: forward conduction at ≤1.2 V (IF = 200 mA) and reverse breakdown at ~33 V. This dual-mode behavior makes it suitable for protecting low-speed signal lines against both positive and negative transients, though dedicated TVS diodes offer faster response for high-energy ESD.
BZX79C33-T50A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- DO-204AH, DO-35, Axial
- Packaging:
- Bulk
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 33 V
- Tolerance:
- ±5%
- Power - Max:
- 500 mW
- Impedance (Max) (Zzt):
- 80 Ohms
- Current - Reverse Leakage @ Vr:
- 50 nA @ 23.1 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.5 V @ 100 mA
- Operating Temperature:
- -65°C ~ 200°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-35
BZX79C33-T50A FAQ
1.How can I place an order for BZX79C33-T50A through Aetrix?
Please submit a Request for Quotation (RFQ) for BZX79C33-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 BZX79C33-T50A reliable?
The price and inventory of BZX79C33-T50A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX79C33-T50A is usually 5 days.
3.What payment methods are accepted for BZX79C33-T50A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX79C33-T50A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BZX79C33-T50A?
BZX79C33-T50A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BZX79C33-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 BZX79C33-T50A?
For technical support, including BZX79C33-T50A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX79C33-T50A requirements.
6.How does Aetrix verify that BZX79C33-T50A is sourced from the original manufacturer or authorized distributors?
All BZX79C33-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 BZX79C33-T50A meets industry standards.
7.What is the process for return or replacement of BZX79C33-T50A?
All BZX79C33-T50A units undergo pre-shipment inspection (PSI). If there is an issue with BZX79C33-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 BZX79C33-T50A part is unused and in its original packaging.
Return procedure for BZX79C33-T50A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
BZX79C33-T50A Tags
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Diodes Incorporated
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onsemi
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