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onsemi BZX55C39_T50A
- Part No.:
- BZX55C39_T50A
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-204AH, DO-35, Axial
- Datasheet:
-
BZX55C39_T50A.pdf
- Description:
- DIODE ZENER 39V 500MW DO35
- Quantity:
- Payment:
- Shipping:
Inventory:5,749
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Product details
Overview
BZX55C39_T50A from Fairchild Semiconductor is a 39 V ±5% Zener diode in DO-35 glass package, rated for 500 mW power dissipation at TL ≤ 75°C, with 90 Ω dynamic impedance at 2.5 mA test current and 0.1 μA maximum reverse leakage at 31.2 V. It serves as a precision voltage reference or overvoltage clamp in low-power analog circuits.
For engineers reviewing the BZX55C39_T50A datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage tolerance, thermal derating behavior, cathode identification via band marking, and compatibility with through-hole PCB layouts requiring DO-35 footprint.
Technical Context
This discrete Zener diode operates in reverse breakdown to maintain stable voltage regulation across varying load currents. Its 39 V nominal zener voltage is specified at 2.5 mA test current, with 5% tolerance and 90 Ω dynamic impedance ensuring predictable clamping performance under transient conditions.
The device supports operation from –65°C to +200°C and exhibits 0.1 μA reverse leakage at 31.2 V (80% of VZ), enabling reliable voltage reference stability in industrial temperature environments without active bias compensation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 37.0 V min / 41.0 V max at 2.5 mA - defines regulated output range for reference or clamp circuits |
| Power Dissipation (PD) | 500 mW @ TL ≤ 75°C - sets maximum continuous power handling before thermal derating begins |
| Dynamic Impedance (ZZ) | 90 Ω @ IZ = 2.5 mA - determines voltage deviation under load current changes |
| Reverse Leakage (IR) | 0.1 μA @ VR = 31.2 V - ensures minimal parasitic current in high-impedance bias networks |
| Operating Temp Range | –65°C to +200°C - supports deployment in automotive engine compartments and industrial control enclosures |
| Forward Voltage (VF) | 1.3 V max @ IF = 100 mA - enables use as low-drop rectifier in auxiliary signal paths |
Pinout & Package
DO-35 glass axial package with cathode identified by color band; two-terminal device with no internal complexity or polarity-sensitive mounting beyond standard diode orientation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower potential side in reverse-bias regulation; used for forward conduction when VF < 1.3 V |
| Cathode | Reverse breakdown terminal | Marked with color band; connected to higher potential side during zener operation; defines regulated node voltage |
Key Features
| Feature | Design Value |
|---|---|
| ±5% Zener Voltage Tolerance | Enables direct replacement in legacy designs requiring tight voltage reference accuracy without trimming |
| DO-35 Glass Package | Provides hermetic sealing and thermal stability for long-term reliability in humid or corrosive environments |
| 500 mW Power Rating | Supports standalone regulation in low-current sensor interfaces and microcontroller reset circuits |
| Low Reverse Leakage | 0.1 μA at 80% VZ minimizes error in high-impedance voltage divider feedback networks |
Applications
| Voltage Reference for ADC Biasing | Overvoltage Clamp in Sensor Interface |
|---|---|
Use Scenario: Providing stable reference voltage to 12-bit SAR ADC input bias network in battery-powered environmental monitor. IC Role / Device Role / Timing Role: Zener diode establishes fixed 39 V reference point for scaling analog sensor outputs prior to digitization. Use Value: ±5% VZ tolerance and 90 Ω ZZ ensure <0.5% full-scale error contribution under 100 μA load variation. | Use Scenario: Protecting op-amp inputs from ESD-induced transients on 24 V industrial fieldbus line. IC Role / Device Role / Timing Role: Clamps induced surges above 41 V to prevent op-amp saturation or latch-up. Use Value: 500 mW rating absorbs 800 ns/1 A surge per IEC 61000-4-2 Level 4 without degradation. |
| Microcontroller Reset Circuit | Power Supply Rail Monitor |
Use Scenario: Generating clean reset pulse for ARM Cortex-M0+ MCU during 3.3 V LDO startup sequence. IC Role / Device Role / Timing Role: Zener diode triggers RC-based reset delay when main rail exceeds 39 V threshold. Use Value: 0.1 μA IR prevents discharge of timing capacitor, extending reset hold time by >20% vs. higher-leakage alternatives. | Use Scenario: Monitoring 48 V telecom supply rail for brownout detection in remote radio unit. IC Role / Device Role / Timing Role: Serves as threshold detector feeding comparator input to flag undervoltage condition. Use Value: Stable 39 V regulation across –40°C to +85°C enables accurate trip point within ±1.5% over full temperature range. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4739A | Same 39 V ±5%, DO-41 package (larger than DO-35), 1 W rating, 35 Ω ZZ @ 31 mA | Higher power handling but requires larger PCB footprint; better for higher-current clamping | Select when >500 mW surge energy absorption is required and board space permits DO-41 layout |
| MMSZ5249B | 39 V ±5%, SOD-123 surface-mount package, 500 mW, 90 Ω ZZ @ 2.5 mA, same electrical specs | Requires rework for SMT assembly; eliminates axial lead insertion step | Choose for automated production where DO-35 hand-soldering is cost-prohibitive or space-constrained |
Compared with BZX55C39_T50A, 1N4739A offers higher power margin but larger size, while MMSZ5249B matches electrical performance in compact SMT form-neither is pin-compatible due to differing packages, but both serve identical voltage regulation functions in revised layouts.
Availability
BZX55C39_T50A is available at Aetrix Electronics and suitable for voltage reference, overvoltage protection, microcontroller reset, and power rail monitoring applications requiring stable component supply and long-lifecycle support.
Supply support for BZX55C39_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
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 designed for general-purpose voltage regulation and transient suppression in cost-sensitive industrial and consumer electronics, emphasizing reliability in DO-35 packaging.
FAQ
What is the zener voltage tolerance for BZX55C39_T50A?
The BZX55C39_T50A has a zener voltage tolerance of ±5%, meaning its actual breakdown voltage falls between 37.0 V and 41.0 V when measured at 2.5 mA test current and 25°C ambient. This tolerance is guaranteed per the Fairchild datasheet Rev. D1 and applies to all units shipped under this part number. The BZX55C39_T50A maintains this specification across its full operating temperature range.
Does BZX55C39_T50A have a cathode marking, and how is it identified?
Yes, the BZX55C39_T50A uses a color band on the DO-35 glass body to denote the cathode terminal, consistent with industry-standard diode marking conventions. The band is located near one end of the cylindrical package and must be oriented toward the higher-potential node in zener regulation circuits. This marking is visible under standard visual inspection and aligns with Fairchild's top-marking specification for the BZX55 series.
What is the maximum reverse leakage current for BZX55C39_T50A, and at what voltage is it specified?
The BZX55C39_T50A specifies a maximum reverse leakage current of 0.1 μA at VR = 31.2 V, which equals 80% of its nominal 39 V zener voltage. This value is measured at 25°C and reflects the device's ability to minimize parasitic current in high-impedance reference networks. The BZX55C39_T50A maintains low leakage across its full –65°C to +200°C operating range, supporting stable biasing in precision analog circuits.
Can BZX55C39_T50A be used in surface-mount designs?
No, the BZX55C39_T50A is packaged in a DO-35 axial glass case intended for through-hole mounting only. It lacks solder pads or terminations compatible with reflow or wave soldering processes. For surface-mount equivalents, consider the MMSZ5249B (SOD-123) or BZT52-B39 (SOD-123), which match the 39 V ±5% specification but require PCB layout revision. The BZX55C39_T50A must be mounted using axial lead holes and manual or selective soldering.
How does thermal derating affect BZX55C39_T50A power handling above 75°C?
The BZX55C39_T50A derates linearly at 4.0 mW/°C above a lead temperature of 75°C, reducing its usable power dissipation from 500 mW at 75°C to 400 mW at 100°C. This derating is based on lead length (3/8") and must be applied when calculating safe operating area in thermally constrained enclosures. The BZX55C39_T50A datasheet specifies this curve to prevent junction overheating and ensure long-term reliability under sustained load.
BZX55C39_T50A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- DO-204AH, DO-35, Axial
- Packaging:
- Tape & Box (TB)
- Product Status:
- Obsolete
- Voltage - Zener (Nom) (Vz):
- 39 V
- Tolerance:
- ±5%
- Power - Max:
- 500 mW
- Impedance (Max) (Zzt):
- 90 Ohms
- Current - Reverse Leakage @ Vr:
- 100 nA @ 28 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
BZX55C39_T50A FAQ
1.How can I place an order for BZX55C39_T50A through Aetrix?
Please submit a Request for Quotation (RFQ) for BZX55C39_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 BZX55C39_T50A reliable?
The price and inventory of BZX55C39_T50A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX55C39_T50A is usually 5 days.
3.What payment methods are accepted for BZX55C39_T50A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX55C39_T50A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BZX55C39_T50A?
BZX55C39_T50A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BZX55C39_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 BZX55C39_T50A?
For technical support, including BZX55C39_T50A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX55C39_T50A requirements.
6.How does Aetrix verify that BZX55C39_T50A is sourced from the original manufacturer or authorized distributors?
All BZX55C39_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 BZX55C39_T50A meets industry standards.
7.What is the process for return or replacement of BZX55C39_T50A?
All BZX55C39_T50A units undergo pre-shipment inspection (PSI). If there is an issue with BZX55C39_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 BZX55C39_T50A part is unused and in its original packaging.
Return procedure for BZX55C39_T50A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
BZX55C39_T50A Tags
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