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onsemi 1SMA5939BT3
- Part No.:
- 1SMA5939BT3
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
1SMA5939BT3.pdf
- Description:
- DIODE ZENER 39V 1.5W SMA
- Quantity:
- Payment:
- Shipping:
Inventory:4,088
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Product details
Overview
1SMA5939BT3 from onsemi is a 1.5 W surface-mount Zener diode with nominal zener voltage of 39 V (±5%), dynamic impedance of 9.6 Ω at 45 mA test current, and maximum DC zener current of 38 A. It features AEC-Q101 qualification, 16 kV HBM ESD rating, and low-profile SMA package for automotive and industrial voltage regulation.
For engineers reviewing the 1SMA5939BT3 datasheet, pinout, applications, or equivalent options, key selection criteria include zener tolerance, thermal resistance (RJA = 250 °C/W), leakage current (0.25 μA @ 31.7 V), power derating above 25°C, and Pb-free compliance per J-STD-609.
Technical Context
This device operates as a precision shunt voltage regulator in reverse-biased mode, maintaining stable output voltage across varying load and line conditions. Its 39 V nominal breakdown is guaranteed at thermal equilibrium with IZT = 45 mA and exhibits temperature coefficient behavior typical of mid-voltage Zeners (≈ +3.5 mV/°C).
The SMA package (Case 403D-02) supports top-slide or bottom-board mounting with flat handling surface and UL 94 V-0 flammability rating. Thermal design must account for 0.5 W max dissipation at TA = 25°C, derating linearly at 4.0 mW/°C above that ambient.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 37.05–40.95 V (±5% tolerance at IZT = 45 mA; defines regulated output range) |
| Zener Impedance (ZZT) | 9.6 Ω (at IZT = 45 mA; determines voltage regulation stiffness under load transients) |
| Max DC Zener Current (IZM) | 38 A (maximum continuous reverse current before thermal runaway at TL = 75°C) |
| Reverse Leakage (IR) | 0.25 μA @ VR = 31.7 V (defines minimum off-state power loss in high-impedance bias networks) |
| Power Dissipation (PD) | 0.5 W @ TA = 25°C (limits usable current in non-heatsinked PCB layouts) |
| Thermal Resistance (RJA) | 250 °C/W (dictates junction-to-ambient temperature rise per watt; requires thermal pad design) |
| ESD Rating | Class 3 (>16 kV HBM) (enables robust handling in automated SMT lines without special ESD controls) |
Pinout & Package
1SMA5939BT3 uses the SMA (DO-214AC) surface-mount package (Case 403D-02), measuring 4.06–4.57 mm in length (E), 2.29–2.92 mm in width (D), and 1.97–2.20 mm in height (A). Cathode is marked by a band; polarity notch confirms cathode orientation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (marked band) | Regulated output reference node | Connected to system ground or lower-potential rail; voltage develops across anode-to-cathode |
| Anode | Input supply connection | Connected to unregulated input; reverse current flows anode-to-cathode during regulation |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive under-hood applications including engine control modules and body electronics |
| 16 kV HBM ESD rating | Eliminates need for external ESD protection in board-level assembly and field service environments |
| Pb-free (RoHS-compliant) | Meets J-STD-609 moisture sensitivity level 1; compatible with lead-free reflow profiles up to 260°C/10 s |
| Low-profile SMA package | Enables high-density layout in space-constrained industrial controllers and telecom power supplies |
| Flat handling surface | Ensures consistent pick-and-place accuracy during automated SMT assembly with <±0.1 mm placement error |
Applications
| Automotive Engine Control Unit (ECU) | Industrial PLC Analog Input Protection |
|---|---|
Use Scenario: Clamping transient overvoltage on 36 V battery-supplied sensor signal lines in diesel engine ECUs. IC Role / Device Role / Timing Role: Shunt voltage clamp protecting ADC front-end against load-dump spikes up to 60 V. Use Value: Maintains 39 V clamping threshold with <9.6 Ω dynamic impedance, limiting peak voltage excursion to safe levels for downstream op-amps. |
Use Scenario: Providing precise 39 V reference for overvoltage detection circuitry in 24 VDC industrial PLC analog input modules. IC Role / Device Role / Timing Role: Stable voltage reference source for comparator-based fault detection thresholds. Use Value: ±5% tolerance ensures repeatable trip points across temperature; 0.25 μA leakage avoids loading high-impedance divider networks. |
| Telecom Power Supply Feedback | Medical Diagnostic Equipment Biasing |
Use Scenario: Secondary-side voltage regulation feedback element in isolated 48 V telecom DC-DC converters. IC Role / Device Role / Timing Role: Precision shunt regulator setting output voltage via optocoupler feedback loop. Use Value: Low 9.6 Ω ZZT minimizes regulation error under varying load; AEC-Q101 qualification supports extended field life. |
Use Scenario: Generating stable bias voltage for photodiode amplifier stages in portable ultrasound imaging systems. IC Role / Device Role / Timing Role: Low-noise voltage reference for analog front-end signal conditioning. Use Value: 16 kV HBM ESD rating prevents damage during clinical handling; Pb-free construction complies with medical RoHS directives. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BZX84-C39LT1G | 0.3 W power rating, SOT-23 package, 39 V ±5%, ZZT = 90 Ω @ 5 mA | Lower power handling limits use to signal-level clamping only; unsuitable for >100 mA regulation | Select when board space is critical and power dissipation remains below 300 mW |
| SMBJ39A | TVS diode, 39 V standoff, 600 W peak pulse power, bidirectional, 1.5 kW surge capability | Designed for transient suppression-not precision regulation; higher leakage (1 μA @ 31.7 V) | Select when primary requirement is ESD/surge protection rather than stable DC voltage reference |
Compared with BZX84-C39LT1G and SMBJ39A, the 1SMA5939BT3 delivers superior regulation stability (9.6 Ω vs. 90 Ω impedance) and higher continuous power (1.5 W vs. 0.3 W), making it optimal for sustained voltage reference and moderate-current shunt regulation where precision and thermal robustness are required.
Availability
1SMA5939BT3 is available at Aetrix Electronics and suitable for automotive engine control units, industrial PLC analog input protection, telecom power supply feedback, and medical diagnostic equipment biasing requiring stable component supply, long-term lifecycle support, and AEC-Q101 compliance.
Supply support for 1SMA5939BT3 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 management, analog, sensors, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The 1SMA59xxBT3 series was designed for high-reliability surface-mount voltage regulation in automotive and industrial environments, emphasizing AEC-Q101 qualification, robust ESD performance, and thermal stability in compact SMA packaging.
FAQ
What is the zener voltage tolerance of the 1SMA5939BT3?
The 1SMA5939BT3 has a zener voltage tolerance of ±5%, with a specified range of 37.05 V to 40.95 V at IZT = 45 mA and thermal equilibrium. This tolerance is guaranteed per device marking and applies across the full operating temperature range of −65°C to +150°C, as confirmed in the official onsemi datasheet revision 7.
Is the 1SMA5939BT3 suitable for automotive applications?
Yes, the 1SMA5939BT3 is AEC-Q101 qualified and PPAP capable, explicitly designated for automotive use with the "SZ" prefix in its full ordering code SZ/1SMA5939BT3G. Its construction, testing, and traceability meet automotive reliability standards for under-hood and chassis-mounted electronics.
What is the maximum power dissipation of the 1SMA5939BT3 at room temperature?
The 1SMA5939BT3 has a maximum DC power dissipation of 0.5 W at ambient temperature (TA) = 25°C. Above 25°C, it must be derated at 4.0 mW/°C, reaching zero dissipation at approximately 150°C ambient - a critical constraint for thermal design in enclosed enclosures or high-power density PCBs.
Does the 1SMA5939BT3 have Pb-free packaging?
Yes, the "G" suffix in the part number (SZ/1SMA5939BT3G) indicates Pb-free packaging compliant with RoHS Directive 2011/65/EU and J-STD-609. The device uses matte tin lead finish and is rated for lead-free reflow soldering up to 260°C for 10 seconds, as verified in the onsemi packaging specification.
What is the reverse leakage current specification for the 1SMA5939BT3?
The 1SMA5939BT3 specifies a maximum reverse leakage current (IR) of 0.25 μA at VR = 31.7 V (80% of nominal VZ). This ultra-low leakage enables use in high-impedance bias networks and precision reference circuits where parasitic current paths must be minimized.
1SMA5939BT3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 1SMA59xxBT3G
- Package/Case:
- DO-214AC, SMA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Voltage - Zener (Nom) (Vz):
- 39 V
- Tolerance:
- ±5%
- Power - Max:
- 1.5 W
- Impedance (Max) (Zzt):
- 45 Ohms
- Current - Reverse Leakage @ Vr:
- 500 nA @ 29.7 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.2 V @ 200 mA
- Operating Temperature:
- -65°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMA
1SMA5939BT3 FAQ
1.How can I place an order for 1SMA5939BT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMA5939BT3 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 1SMA5939BT3 reliable?
The price and inventory of 1SMA5939BT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMA5939BT3 is usually 5 days.
3.What payment methods are accepted for 1SMA5939BT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMA5939BT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMA5939BT3?
1SMA5939BT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMA5939BT3 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 1SMA5939BT3?
For technical support, including 1SMA5939BT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMA5939BT3 requirements.
6.How does Aetrix verify that 1SMA5939BT3 is sourced from the original manufacturer or authorized distributors?
All 1SMA5939BT3 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 1SMA5939BT3 meets industry standards.
7.What is the process for return or replacement of 1SMA5939BT3?
All 1SMA5939BT3 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMA5939BT3, 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 1SMA5939BT3 part is unused and in its original packaging.
Return procedure for 1SMA5939BT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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