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onsemi BZX79C51_T50R
- Part No.:
- BZX79C51_T50R
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-204AH, DO-35, Axial
- Datasheet:
-
BZX79C51_T50R.pdf
- Description:
- DIODE ZENER 51V 500MW DO35
- Quantity:
- Payment:
- Shipping:
Inventory:8,838
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Product details
Overview
BZX79C51_T50R from ON Semiconductor is a 51 V, ±5% tolerance Zener diode in DO-35 glass package, rated for 500 mW power dissipation at TL ≤ 75°C, with 180 Ω dynamic impedance at 2 mA test current and 0.5 μA leakage current at 39.2 V reverse voltage. It serves as a precision voltage reference or overvoltage clamp in low-power analog circuits.
For engineers reviewing the BZX79C51_T50R datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage tolerance, thermal derating behavior, junction capacitance (19 pF at 0 V), temperature coefficient (+2.5 mV/°C), and DO-35 mechanical compatibility with through-hole PCB layouts.
Technical Context
The BZX79C51_T50R operates as a silicon planar Zener diode optimized for stable voltage regulation in low-current, non-switching applications. Its 51 V nominal breakdown voltage is specified at 2 mA test current, with a positive temperature coefficient of +2.5 mV/°C indicating increasing VZ with rising junction temperature.
It exhibits 180 Ω dynamic impedance (ZZ) at IZ = 2 mA, 19 pF junction capacitance measured at 0 V and 1 MHz, and forward voltage ≤1.5 V at 100 mA - confirming suitability for bidirectional protection and reference roles where low leakage (<0.5 μA at VR = 39.2 V) and predictable TC are required.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage | 51 V ±5% (48.45–53.55 V), specified at IZ = 2 mA - defines precise clamping threshold for voltage-sensitive nodes |
| Power Dissipation | 500 mW @ TL ≤ 75°C - sets maximum continuous power handling before thermal derating begins |
| Dynamic Impedance | 180 Ω @ IZ = 2 mA - determines regulation stiffness and output voltage variation under load changes |
| Leakage Current | 0.5 μA max @ VR = 39.2 V - ensures minimal standby current in high-impedance bias/reference paths |
| Junction Capacitance | 19 pF @ VR = 0 V, f = 1 MHz - impacts high-frequency noise coupling and AC signal integrity in filtering apps |
| Temperature Coefficient | +2.5 mV/°C - enables predictable VZ drift compensation in temperature-stable references |
| Forward Voltage | ≤1.5 V @ IF = 100 mA - supports use as bidirectional ESD clamp or polarity-insensitive protection device |
Pinout & Package
DO-35 glass axial package with cathode band marking; two-terminal device requiring no external biasing. Leads are tinned copper-clad steel, 3/8″ length standard for thermal rating compliance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / Zener cathode reference ground | Connected to lower-potential node; reverse-biased operation places cathode at regulated voltage above anode |
| Cathode | Zener breakdown terminal / voltage reference output | Marked with color band; supplies stable 51 V relative to anode when reverse biased ≥39.2 V |
Key Features
| Feature | Design Value |
|---|---|
| ±5% Zener voltage tolerance | Enables tight voltage reference design without post-calibration in cost-sensitive consumer and industrial controls |
| DO-35 glass package | Provides hermetic sealing and stable long-term VZ drift <1% over 1000 hrs at rated power |
| +2.5 mV/°C temperature coefficient | Allows predictable thermal compensation in dual-diode reference configurations or ambient-compensated sensors |
| 19 pF junction capacitance | Minimizes signal loading in RF detector bias networks and high-impedance op-amp reference inputs |
| 0.5 μA max leakage at 39.2 V | Preserves battery life in always-on monitoring circuits and enables use in ultra-low-power sensor front-ends |
Applications
| Power Supply Monitoring | Overvoltage Protection |
|---|---|
Use Scenario: Monitoring 48 V telecom line voltage for brownout/overvoltage detection in remote base station controllers. IC Role / Device Role / Timing Role: Zener reference input to comparator IC, providing stable 51 V trip threshold independent of supply ripple. Use Value: Tight ±5% VZ tolerance ensures accurate fault detection across production units without trimming. | Use Scenario: Clamping transient surges on 36 V automotive body control module (BCM) sensor inputs. IC Role / Device Role / Timing Role: Shunt protection element diverting excess energy to ground during ISO 7637-2 pulse 1/2a events. Use Value: 500 mW power rating and 180 Ω ZZ enable reliable clamping without thermal runaway under repeated transients. |
| Voltage Reference for ADC | LED Current Regulation |
Use Scenario: Providing reference voltage to 12-bit SAR ADC in industrial temperature transmitter with 4–20 mA loop. IC Role / Device Role / Timing Role: Precision DC reference source for ADC internal reference buffer or external ratiometric scaling. Use Value: +2.5 mV/°C TC allows predictable drift modeling; 19 pF capacitance avoids sampling-time settling errors. | Use Scenario: Setting constant current for high-brightness white LED string in emergency lighting driver. IC Role / Device Role / Timing Role: Voltage reference for LM317-based adjustable current regulator, defining IOUT = 1.25 V / RSET. Use Value: Low 0.5 μA leakage ensures stable reference voltage even at elevated ambient temperatures up to +85°C. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N5257B | Same 51 V nominal, ±5% tolerance, but DO-35 package with 170 Ω ZZ @ 20 mA (not 2 mA); higher test current shifts operating point | Less suitable for low-current references; better for higher-power shunt regulation where 20 mA bias is acceptable | Select BZX79C51_T50R for 2 mA–5 mA bias designs; choose 1N5257B only if circuit already uses 20 mA Zener bias |
| MMSZ5257B-TP | SOD-123 surface-mount package, same 51 V/±5%, but 100 Ω ZZ @ 20 mA and 0.1 μA leakage @ 39.2 V - superior leakage but different test condition and footprint | Requires PCB redesign; not drop-in; preferred for space-constrained, automated assembly environments | Use MMSZ5257B-TP only when SMT migration is planned; BZX79C51_T50R remains optimal for legacy through-hole or prototyping use |
Compared with 1N5257B and MMSZ5257B-TP, the BZX79C51_T50R offers the lowest leakage at its specified test condition (0.5 μA @ 39.2 V), matched DO-35 mechanical fit for existing through-hole designs, and ZZ characterized at 2 mA - aligning with typical low-power reference bias currents.
Availability
BZX79C51_T50R is available at Aetrix Electronics and suitable for power supply monitoring, overvoltage protection, and precision voltage reference applications requiring stable component supply, long-lifecycle support, and traceable sourcing for industrial and telecom equipment.
Supply support for BZX79C51_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
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 BZX79C51_T50R belongs to the BZX79C series of general-purpose Zener diodes designed for cost-effective, reliable voltage regulation and reference functions in low-to-medium power linear circuits.
FAQ
What is the exact Zener voltage tolerance for BZX79C51_T50R?
The BZX79C51_T50R has a guaranteed Zener voltage tolerance of ±5% around its nominal 51 V rating, meaning the actual measured VZ falls between 48.45 V and 53.55 V when tested at IZ = 2 mA and TL = 30°C. This tolerance is confirmed in the official ON Semiconductor datasheet revision 3 (November 2017) and applies to all units shipped under this part number.
Does BZX79C51_T50R support surface-mount assembly?
No, the BZX79C51_T50R uses a DO-35 glass axial package with radial leads intended for through-hole mounting. It is not compatible with reflow or wave soldering processes used for SMT. For surface-mount alternatives, consider the MMSZ5257B-TP in SOD-123, but note differences in test current, impedance, and thermal characteristics versus the BZX79C51_T50R.
What is the maximum allowable reverse voltage before breakdown for BZX79C51_T50R?
The BZX79C51_T50R begins controlled Zener breakdown at its specified test voltage of 51 V ±5% when biased at IZ = 2 mA. Below 39.2 V reverse voltage, leakage remains ≤0.5 μA. Operation below this knee voltage does not trigger regulation; sustained reverse bias above 53.55 V may exceed safe power limits unless current is strictly limited by external resistance.
How does temperature affect the Zener voltage of BZX79C51_T50R?
The BZX79C51_T50R has a positive temperature coefficient of +2.5 mV/°C, meaning its Zener voltage increases by approximately 2.5 mV for every 1°C rise in junction temperature. This behavior is documented in the Electrical Characteristics table and must be accounted for in precision reference designs operating across –65°C to +200°C ambient ranges.
Can BZX79C51_T50R be used for bidirectional ESD protection?
The BZX79C51_T50R conducts forward current ≤1.5 V at 100 mA and regulates in reverse at ~51 V, making it unsuitable as a standalone bidirectional ESD clamp. Its asymmetric behavior and lack of defined clamping voltage in forward direction limit use to unidirectional voltage reference or overvoltage protection. For true bidirectional protection, dedicated TVS diodes like SMBJ51A are recommended instead of the BZX79C51_T50R.
BZX79C51_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):
- 51 V
- Tolerance:
- ±5%
- Power - Max:
- 500 mW
- Impedance (Max) (Zzt):
- 180 Ohms
- Current - Reverse Leakage @ Vr:
- 500 nA @ 35.7 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
BZX79C51_T50R FAQ
1.How can I place an order for BZX79C51_T50R through Aetrix?
Please submit a Request for Quotation (RFQ) for BZX79C51_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 BZX79C51_T50R reliable?
The price and inventory of BZX79C51_T50R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX79C51_T50R is usually 5 days.
3.What payment methods are accepted for BZX79C51_T50R?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX79C51_T50R transactions.
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BZX79C51_T50R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BZX79C51_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 BZX79C51_T50R?
For technical support, including BZX79C51_T50R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX79C51_T50R requirements.
6.How does Aetrix verify that BZX79C51_T50R is sourced from the original manufacturer or authorized distributors?
All BZX79C51_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 BZX79C51_T50R meets industry standards.
7.What is the process for return or replacement of BZX79C51_T50R?
All BZX79C51_T50R units undergo pre-shipment inspection (PSI). If there is an issue with BZX79C51_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 BZX79C51_T50R part is unused and in its original packaging.
Return procedure for BZX79C51_T50R:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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