My Inquiry
My Account
onsemi BZX79C20-T50A
- Part No.:
- BZX79C20-T50A
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-204AH, DO-35, Axial
- Datasheet:
-
BZX79C20-T50A.pdf
- Description:
- DIODE ZENER 20V 500MW DO35
- Quantity:
- Payment:
- Shipping:
Inventory:120,000
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
BZX79C20-T50A from onsemi is a 20 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 −65 °C to +200 °C operating temperature - used for precision voltage regulation in low-power analog reference and overvoltage protection circuits.
For engineers reviewing the BZX79C20-T50A datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage tolerance at 5 mA, thermal derating above 75 °C, leakage current at rated reverse voltage, junction capacitance at 0 V, and compatibility with fan-fold tape packaging for automated assembly.
Technical Context
The BZX79C20-T50A operates as a silicon planar Zener diode with sharp reverse breakdown at 20 V nominal, exhibiting a temperature coefficient of +3.7 mV/°C (typical) and 100 Ω dynamic impedance (ZZ) measured at IZ = 5 mA. Its glass-encapsulated DO-204AH construction ensures hermetic sealing and stable long-term voltage reference performance.
It supports continuous DC regulation up to 500 mW at lead temperature ≤75 °C, with linear derating of 4.0 mW/°C above that threshold. Forward voltage is specified ≤1.2 V at IF = 200 mA, confirming suitability for bidirectional clamping or dual-purpose biasing applications where forward conduction may occur.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 20 V nominal, ±5% tolerance (19.0–21.0 V) at IZ = 5 mA - defines stable regulation point for reference design |
| Power Dissipation (PD) | 500 mW @ TL ≤ 75 °C - sets maximum steady-state power handling before thermal derating applies |
| Dynamic Impedance (ZZ) | 100 Ω max @ IZ = 5 mA - determines output voltage variation under load current changes |
| Leakage Current (IR) | 0.05 μA max @ VR = 14.0 V - ensures minimal error current in high-impedance reference nodes |
| Junction Capacitance (CJ) | 47 pF max @ VR = 0 V, f = 1 MHz - impacts high-frequency noise filtering and transient response |
| Temperature Coefficient (TC) | +3.7 mV/°C typical - quantifies drift rate of VZ over temperature, critical for wide-range stability |
| Forward Voltage (VF) | ≤1.2 V @ IF = 200 mA - enables use in polarity-insensitive clamp or dual-direction protection |
Pinout & Package
DO-204AH (Case 017AG) axial-lead glass package: hermetically sealed, 4.56 mm body length, 1.91 mm diameter, 25.4 mm minimum lead length (T50), weight 0.137 g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (A) | Reverse-biased cathode connection terminal | Connected to lower-potential node in Zener regulation; carries full load current during breakdown |
| Cathode (K) | Reverse-biased anode connection terminal | Connected to higher-potential node; defines regulated output voltage referenced to anode |
Key Features
| Feature | Design Value |
|---|---|
| ±5% Zener voltage tolerance | Enables tight regulation without post-manufacture trimming in cost-sensitive consumer and industrial references |
| Hermetically sealed glass package | Prevents moisture ingress and parameter drift over time, supporting >10-year reliability in harsh environments |
| Linear thermal derating (4.0 mW/°C) | Allows predictable power budgeting across −65 °C to +200 °C ambient without abrupt failure modes |
| Low leakage (0.05 μA max) | Minimizes loading error in high-impedance feedback networks and battery-powered sensor references |
| Fan-fold tape packaging (T50A) | Supports high-speed pick-and-place placement with consistent orientation and no reel changeover delays |
Applications
| Industrial Sensor Reference | USB Port Overvoltage Clamp |
|---|---|
Use Scenario: Providing stable 20 V reference for 16-bit ADC biasing in programmable logic controller analog input modules. IC Role / Device Role / Timing Role: Precision shunt voltage reference establishing fixed node voltage for ratiometric measurement scaling. Use Value: ±5% VZ tolerance and <100 Ω ZZ ensure <0.1% full-scale error contribution under 1 mA load variation. |
Use Scenario: Clamping transient surges on USB VBUS line during hot-plug events in embedded host controllers. IC Role / Device Role / Timing Role: Bidirectional overvoltage protector limiting VBUS to 20 V during ESD or inductive kickback. Use Value: 1.2 V forward drop allows safe conduction during reverse polarity faults; 500 mW rating absorbs 100 ns/1 A transients per IEC 61000-4-2 Level 4. |
| Automotive Cabin Control Panel | Smoke Detector Power Supply |
Use Scenario: Regulating 20 V rail for microcontroller I/O buffer supply in HVAC control head units exposed to automotive temperature cycling. IC Role / Device Role / Timing Role: Primary shunt regulator maintaining stable logic supply despite 9–16 V battery fluctuations. Use Value: +3.7 mV/°C TC and −65 °C to +200 °C rating enable <1.5% total VZ shift across full automotive ambient range. |
Use Scenario: Generating stable 20 V bias for ionization chamber amplifier in battery-backed residential smoke alarms. IC Role / Device Role / Timing Role: Low-leakage voltage reference enabling >5-year shelf life with <0.05 μA standby drain. Use Value: 0.05 μA max IR at 14 V prevents measurable battery depletion over 10-year service life. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4744A | 20 V nominal, ±5%, 1 W power rating, DO-41 package, 25 Ω ZZ, +5.0 mV/°C TC | Higher power handling but larger footprint; better regulation stability under varying load, worse thermal drift | Select when >500 mW dissipation or lower dynamic impedance is required; verify PCB pad compatibility with DO-41 vs DO-204AH |
| BZX55C20 | 20 V nominal, ±5%, 500 mW, DO-35 package, 100 Ω ZZ, +3.5 mV/°C TC, 0.1 μA IR | Same power and tolerance, but smaller DO-35 glass case; slightly higher leakage and different thermal mass | Choose for space-constrained layouts where DO-35 fits; confirm mechanical retention strength meets vibration requirements |
Compared with BZX79C20-T50A, the 1N4744A offers higher power and lower impedance but requires board rework for DO-41 pads, while the BZX55C20 matches power and tolerance in a smaller package but trades off 0.05 μA vs 0.1 μA leakage - making BZX79C20-T50A optimal for mid-volume, thermally stable, fan-fold assembly applications.
Availability
BZX79C20-T50A is available at Aetrix Electronics and suitable for industrial sensor reference, USB port overvoltage clamp, and automotive cabin control panel designs requiring stable component supply with consistent fan-fold tape packaging.
Supply support for BZX79C20-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 focused on energy-efficient electronics, delivering silicon solutions for automotive, industrial, cloud, and IoT applications.
The BZX79C series belongs to onsemi's legacy Zener diode portfolio designed specifically for general-purpose voltage regulation and transient suppression in cost-sensitive, high-reliability applications across consumer, industrial, and automotive markets.
FAQ
What is the exact Zener voltage tolerance for BZX79C20-T50A?
The BZX79C20-T50A has a nominal Zener voltage of 20 V with a guaranteed tolerance of ±5%, meaning the actual breakdown voltage falls between 19.0 V and 21.0 V when measured at IZ = 5 mA and TL = 30 °C. This tolerance is confirmed in the Electrical Characteristics table of the official onsemi datasheet (Rev. 5, December 2023), and applies strictly to the BZX79C20-T50A variant within the BZX79C2V4–BZX79C18 family.
Does BZX79C20-T50A support automated SMT assembly?
No - the BZX79C20-T50A uses an axial-lead DO-204AH (Case 017AG) package and ships in fan-fold tape (T50A), which is intended for axial automatic insertion equipment, not surface-mount reflow. It lacks solder pads or terminations compatible with pick-and-place machines or reflow ovens. For SMT-compatible alternatives, consider the SOD-123 packaged BZX84-C20 or similar variants, but note these differ in thermal performance and electrical specs from the BZX79C20-T50A.
What is the maximum allowable reverse voltage before breakdown for BZX79C20-T50A?
The BZX79C20-T50A begins controlled Zener breakdown at its specified nominal voltage of 20 V, with full regulation established at IZ = 5 mA. Below this current, reverse voltage can rise up to the rated VR = 14.0 V while maintaining leakage current ≤0.05 μA. Exceeding 21.0 V (the upper limit of its ±5% tolerance band) risks uncontrolled avalanche and potential parametric shift - so 14.0 V is the safe non-breakdown reverse bias limit, and 20 V is the functional regulation point.
How does the temperature coefficient affect BZX79C20-T50A in real-world operation?
The BZX79C20-T50A exhibits a typical temperature coefficient of +3.7 mV/°C, meaning its Zener voltage increases by approximately 3.7 mV for every 1 °C rise in junction temperature. Over a −40 °C to +85 °C ambient range, this results in ~465 mV total drift - a 2.3% shift relative to 20 V. Designers must account for this in precision references; the BZX79C20-T50A is best suited for applications where such drift is acceptable or compensated via system-level calibration.
Is BZX79C20-T50A RoHS compliant and halogen-free?
Yes - the BZX79C20-T50A is RoHS compliant and halogen-free per onsemi's product compliance documentation (document number 100-000019, "Environmental Compliance Status"). The DO-204AH glass package contains no lead in solderable terminations, and all materials meet EU Directive 2011/65/EU and JEDEC JS709C requirements. Full compliance data, including substance declarations and test reports, is accessible via onsemi's website under the BZX79C20-T50A product page.
BZX79C20-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):
- 20 V
- Tolerance:
- ±5%
- Power - Max:
- 500 mW
- Impedance (Max) (Zzt):
- 55 Ohms
- Current - Reverse Leakage @ Vr:
- 50 nA @ 14 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
BZX79C20-T50A FAQ
1.How can I place an order for BZX79C20-T50A through Aetrix?
Please submit a Request for Quotation (RFQ) for BZX79C20-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 BZX79C20-T50A reliable?
The price and inventory of BZX79C20-T50A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX79C20-T50A is usually 5 days.
3.What payment methods are accepted for BZX79C20-T50A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX79C20-T50A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BZX79C20-T50A?
BZX79C20-T50A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BZX79C20-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 BZX79C20-T50A?
For technical support, including BZX79C20-T50A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX79C20-T50A requirements.
6.How does Aetrix verify that BZX79C20-T50A is sourced from the original manufacturer or authorized distributors?
All BZX79C20-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 BZX79C20-T50A meets industry standards.
7.What is the process for return or replacement of BZX79C20-T50A?
All BZX79C20-T50A units undergo pre-shipment inspection (PSI). If there is an issue with BZX79C20-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 BZX79C20-T50A part is unused and in its original packaging.
Return procedure for BZX79C20-T50A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
BZX79C20-T50A Tags
-
MMBZ5240B-7-F
Diodes Incorporated
-
BZT52C5V6T-7
Diodes Incorporated
-
MMSZ5231B-7-F
Diodes Incorporated
-
BZT52C15-7-F
Diodes Incorporated
-
BZX84C3V3LT1G
onsemi
-
MMSZ5245BS-7-F
Diodes Incorporated
-
MMSZ4682T1G
onsemi
-
BZT52C15S-7-F
Diodes Incorporated
-
MM5Z5V1ST1G
onsemi
-
SMAJ4744A-TP
Micro Commercial Co
-
BZT52C3V6LP-7
Diodes Incorporated
-
SMAZ12-13-F
Diodes Incorporated
Tech Hub
Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …
A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
