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onsemi 1N957B
- Part No.:
- 1N957B
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-204AH, DO-35, Axial
- Datasheet:
-
1N957B.pdf
- Description:
- DIODE ZENER 6.8V 500MW DO35
- Quantity:
- Payment:
- Shipping:
Inventory:41,751
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Product details
Overview
1N957B from onsemi is a 500 mW, ±5% tolerance, 6.8 V nominal Zener voltage regulator diode in a DO-35 (DO-204AH) hermetically sealed glass package. It operates from –65°C to +200°C, delivers 18.5 Ω dynamic impedance at 18.5 mA test current, and supports 150 mA maximum DC zener current. It is used for precision voltage reference and overvoltage protection in low-power analog power rails.
For engineers reviewing the 1N957B datasheet, pinout, applications, or equivalent options, this page provides verified electrical parameters, thermal derating curves, leakage behavior at 5.2 V, and validated alternatives for voltage regulation in industrial sensor interfaces and legacy analog circuitry.
Technical Context
The 1N957B employs a silicon-oxide passivated junction with double-slug metallurgical bonded construction, enabling stable Zener operation under thermal stress and high ESD immunity (>16 kV HBM). Its 6.8 V nominal breakdown is specified at 18.5 mA (IZT), with tight 6.46–7.14 V min/max limits confirming ±5% tolerance per the "B" suffix designation.
Thermal performance is defined by lead-to-ambient resistance (θLA ≈ 30–40°C/W) and junction-to-lead resistance (θJL), supporting steady-state dissipation up to 500 mW at TL ≤ 75°C, derating linearly at 4.0 mW/°C above that. Leakage remains ≤1.0 µA at VR = 5.2 V, critical for low-current bias networks.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 6.46–7.14 V @ IZT = 18.5 mA - ensures ±5% regulation accuracy across production lot |
| Zener Impedance (ZZT) | 18.5 Ω @ IZT - defines AC regulation error under dynamic load transients |
| Max Power Dissipation | 500 mW @ TL ≤ 75°C - sets absolute thermal limit for PCB trace or clip mounting |
| Leakage Current (IR) | ≤1.0 µA @ VR = 5.2 V - guarantees minimal error in high-impedance reference dividers |
| Operating Temp Range | –65°C to +200°C - enables use in automotive under-hood, aerospace, and industrial oven controls |
| ESD Rating | Class 3 (>16 kV HBM) - protects against handling damage during manual assembly or field service |
| Package | DO-35 (DO-204AH) - axial-leaded, hermetically sealed glass housing with cathode band marking |
Pinout & Package
Package: DO-35 (DO-204AH), axial-lead, hermetically sealed glass case with cathode indicated by a painted polarity band. Leads are corrosion-resistant and solderable at 230°C for 10 seconds at 1/16″ from case.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / Zener cathode reference node | Connected to lower-potential rail; reverse-biased operation requires anode grounded or at lower voltage than cathode |
| Cathode | Zener breakdown terminal / regulated output node | Marked with band; supplies stable 6.8 V reference when reverse-biased at ≥18.5 mA |
Key Features
| Feature | Design Value |
|---|---|
| ±5% Zener tolerance (B-suffix) | Guarantees 6.46–7.14 V regulation window without post-manufacturing sorting |
| Double-slug metallurgical bond | Enhances thermal coupling between junction and leads, improving power handling stability |
| Hermetic glass sealing | Prevents moisture ingress and long-term parameter drift in humid or corrosive environments |
| ESD robustness >16 kV HBM | Eliminates need for external ESD protection in manual handling or low-speed signal paths |
| Lead temperature rating 230°C | Supports standard wave and hand-soldering processes without junction damage |
Applications
| Industrial Sensor Signal Conditioning | Legacy Analog Power Supply Reference |
|---|---|
|
Use Scenario: Providing stable 6.8 V reference for 4–20 mA transmitter front-end op-amps in factory-floor pressure/temperature sensors. IC Role / Device Role / Timing Role: Zener diode operating in reverse breakdown to generate fixed bias voltage for amplifier input stages. Use Value: Tight ±5% tolerance and <1 µA leakage ensure reference error stays below 0.2% FS over –40°C to +85°C ambient. |
Use Scenario: Regulating auxiliary 6.8 V rail in vintage PLC I/O modules using discrete transistor-based linear regulators. IC Role / Device Role / Timing Role: Shunt voltage regulator absorbing excess current to maintain constant output voltage under variable load. Use Value: 500 mW power rating and DO-35 form factor allow direct replacement of obsolete 1N4734A in through-hole designs. |
| Automotive Cabin Control Panel | Medical Instrumentation Bias Network |
|
Use Scenario: Clamping and referencing microcontroller ADC reference inputs in HVAC control panels exposed to under-dash thermal cycling. IC Role / Device Role / Timing Role: Precision voltage clamp protecting ADC input from transient overvoltage while supplying stable VREF. Use Value: –65°C to +200°C operating range and hermetic seal prevent calibration drift during thermal shock testing. |
Use Scenario: Generating low-noise bias for photodiode transimpedance amplifiers in portable blood oximeters. IC Role / Device Role / Timing Role: Low-leakage (≤1 µA) Zener providing quiet DC reference in ultra-low-current analog front-ends. Use Value: Sub-µA leakage at 80% VR and 18.5 Ω ZZT minimize Johnson noise contribution to system SNR. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4734A | Same 6.8 V nominal, but ±5% tolerance achieved via binning; higher ZZT (10 Ω typical vs. 18.5 Ω max for 1N957B); JEDEC DO-41 package (larger than DO-35) | Used in newer consumer-grade power supplies where board space is less constrained and tighter dynamic impedance is preferred | Select 1N4734A only if DO-41 footprint is acceptable and lower impedance at 20 mA is required; not drop-in due to package size and lead pitch |
| BZX55C6V8 | 6.8 V ±5%, 500 mW, DO-35 package, but rated for 100 °C TJ max (vs. +200°C for 1N957B); leakage 0.5 µA @ 5.44 V (tighter than 1N957B's 1.0 µA @ 5.2 V) | Common in commercial telecom and computing power management where extended temperature range is unnecessary | Choose BZX55C6V8 for cost-sensitive, non-military/industrial designs; avoid where operation above 100°C ambient is expected |
Compared with 1N4734A and BZX55C6V8, the 1N957B uniquely combines hermetic DO-35 packaging, +200°C capability, and guaranteed 18.5 Ω max impedance - making it the only option qualified for high-reliability, high-temperature analog references where long-term parameter stability is mandatory.
Availability
1N957B is available at Aetrix Electronics and suitable for industrial sensor conditioning, legacy analog power supply reference, and automotive cabin control panel applications requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for 1N957B 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 innovation for automotive, industrial, cloud, medical, and IoT applications.
The 1N957B belongs to the legacy 1N9xxB series of hermetically sealed Zener regulators, designed specifically for high-reliability analog voltage reference and protection in harsh-environment systems where long-term stability and thermal resilience are critical.
FAQ
What is the exact Zener voltage tolerance of the 1N957B?
The 1N957B has a guaranteed ±5% Zener voltage tolerance, confirmed by its "B" suffix designation and documented min/nom/max values of 6.46 V / 6.8 V / 7.14 V at IZT = 18.5 mA. This tolerance is measured under thermal equilibrium at lead temperature TL = 30°C ± 1°C with 3/8″ lead length, per the official onsemi datasheet revision 1.
Can the 1N957B be used in surface-mount designs?
No, the 1N957B is exclusively available in the axial-leaded DO-35 (DO-204AH) glass package and is not offered in any surface-mount variant. It requires through-hole mounting with leads bent to fit PCB hole spacing. For SMT equivalents, engineers must select other families such as MMBZ52xxBL or BZX84-C6V8, which differ in power rating, impedance, and temperature range.
What is the maximum reverse leakage current for the 1N957B at 5.2 V?
The 1N957B exhibits a maximum reverse leakage current (IR) of 1.0 µA at VR = 5.2 V (80% of nominal Zener voltage), as specified in the Electrical Characteristics table. This value is measured at TA = 25°C and is critical for ensuring minimal error in high-impedance bias networks and precision reference dividers.
How does the 1N957B's thermal derating work above 75°C?
The 1N957B's steady-state power dissipation derates linearly at 4.0 mW/°C above a lead temperature (TL) of 75°C, dropping from 500 mW at TL ≤ 75°C to zero at TL = 200°C. This derating curve is defined in Figure 1 of the datasheet and must be applied based on actual measured lead temperature-not ambient-due to thermal resistance between junction and lead.
Is the 1N957B suitable for automotive under-hood applications?
Yes, the 1N957B is qualified for automotive under-hood use due to its –65°C to +200°C operating and storage temperature range, hermetic glass sealing, and 16 kV HBM ESD rating. Its double-slug construction and metallurgical bonding provide mechanical and thermal robustness needed in engine compartment environments where thermal cycling and vibration are severe.
1N957B Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- DO-204AH, DO-35, Axial
- Packaging:
- Bulk
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 6.8 V
- Tolerance:
- ±5%
- Power - Max:
- 500 mW
- Impedance (Max) (Zzt):
- 4.5 Ohms
- Current - Reverse Leakage @ Vr:
- 150 µA @ 5.2 V
- Voltage - Forward (Vf) (Max) @ If:
- -
- Operating Temperature:
- -65°C ~ 200°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-35
1N957B FAQ
1.How can I place an order for 1N957B through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N957B 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 1N957B reliable?
The price and inventory of 1N957B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N957B is usually 5 days.
3.What payment methods are accepted for 1N957B?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N957B transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N957B?
1N957B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N957B 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 1N957B?
For technical support, including 1N957B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N957B requirements.
6.How does Aetrix verify that 1N957B is sourced from the original manufacturer or authorized distributors?
All 1N957B 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 1N957B meets industry standards.
7.What is the process for return or replacement of 1N957B?
All 1N957B units undergo pre-shipment inspection (PSI). If there is an issue with 1N957B, 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 1N957B part is unused and in its original packaging.
Return procedure for 1N957B:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1N957B 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
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