My Inquiry
My Account
onsemi SZ1SMB5939BT3G
- Part No.:
- SZ1SMB5939BT3G
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SZ1SMB5939BT3G.pdf
- Description:
- DIODE ZENER 39V 3W SMB
- Quantity:
- Payment:
- Shipping:
Inventory:2,701
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SZ1SMB5939BT3G from onsemi is a 3 W surface-mount Zener diode with nominal Zener voltage of 39 V (±5%), maximum Zener impedance of 9.6 Ω at 45 mA test current, and reverse leakage current ≤0.25 μA at 31.2 V, designed for precision voltage regulation in automotive power supply rails and industrial overvoltage protection circuits.
For engineers reviewing the SZ1SMB5939BT3G datasheet, pinout, applications, or equivalent options, key selection criteria include Zener voltage tolerance, thermal resistance (226 °C/W), surge power capability (up to 100 W for 1 ms), AEC−Q101 qualification status, and SMB package compatibility with automated SMT assembly.
Technical Context
This device operates as a two-terminal voltage reference using avalanche breakdown in silicon, with a specified Zener voltage range of 37.05 V to 40.95 V at IZT = 45 mA and temperature coefficient optimized for stable regulation above 30 V. Its thermal resistance from junction-to-ambient is 226 °C/W on FR-4 board, requiring careful PCB copper area design for sustained 3 W dissipation.
The SZ1SMB5939BT3G features Class 3 ESD rating (>16 kV HBM), Pb-free construction per J-STD-020, and AEC−Q101 qualification-making it suitable for automotive body electronics and under-hood control modules where reliability under thermal cycling and transient stress is critical.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 39 V nominal (37.05–40.95 V range); enables stable 39 V rail clamping in 42 V automotive systems. |
| Power Dissipation (PD) | 3.0 W @ TL = 75°C; derates linearly to 550 mW @ TA = 25°C-requires thermal pad design for continuous operation. |
| Zener Impedance (ZZT) | 9.6 Ω max @ IZT = 45 mA; ensures low dynamic error during load transients in feedback loops. |
| Reverse Leakage (IR) | ≤0.25 μA @ VR = 31.2 V; minimizes standby current in battery-sensitive applications. |
| Thermal Resistance (RJA) | 226 °C/W; dictates minimum copper area (≥25 mm² recommended) for safe operation at full power. |
| ESD Rating | Class 3 (>16 kV HBM); eliminates need for external ESD protection in infotainment and sensor interface designs. |
| AEC−Q101 Qualified | Yes-validates suitability for automotive grade-2 (−40°C to +105°C ambient) applications without requalification. |
Pinout & Package
Package: SMB (Case 403A), surface-mount plastic package with modified L-bend leads, cathode indicated by polarity band, UL 94 V-0 flammability rating, and Pb-free construction.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / Reference ground node | Connected to system ground or lower-potential rail; must be routed with low-inductance path for transient response. |
| Cathode | Zener breakdown terminal / Regulated output node | Connected to protected node (e.g., IC supply rail); polarity band identifies this terminal for correct orientation during placement. |
Key Features
| Feature | Design Value |
|---|---|
| AEC−Q101 qualification | Validated for automotive-grade reliability including temperature cycling, humidity bias, and mechanical shock testing. |
| Flat handling surface | Enables high-accuracy pick-and-place placement with <±0.1 mm X/Y repeatability on standard SMT lines. |
| Top-side or bottom-side mounting | Supports dual-sided PCB assembly without rework-reduces board area and simplifies layout in space-constrained ECUs. |
| 16 kV HBM ESD rating | Eliminates need for discrete TVS diodes in CAN/LIN bus power domains, reducing BOM count and cost. |
| Void-free transfer-molded plastic case | Ensures consistent thermal performance and long-term moisture resistance in humid under-hood environments. |
Applications
| Automotive Body Control Module (BCM) | Industrial PLC Input Protection |
|---|---|
Use Scenario: Clamping 42 V battery transients on microcontroller I/O supply rails during load dump events. IC Role / Device Role / Timing Role: Two-terminal voltage clamp protecting 3.3 V/5 V regulators from >60 V spikes lasting up to 400 ms. Use Value: Prevents regulator latch-up and MCU reset without adding series resistance or timing delay in safety-critical functions. |
Use Scenario: Protecting 24 V digital input channels from field-wiring induced surges in factory automation cabinets. IC Role / Device Role / Timing Role: Standby-mode shunt regulator that activates only during overvoltage events ≥31.2 V. Use Value: Maintains <0.25 μA leakage during normal operation while delivering 900 mA peak surge current for 1 ms pulses. |
| Telecom Power Supply Monitoring | Medical Diagnostic Equipment Bias Supply |
Use Scenario: Providing reference voltage for analog front-end comparators monitoring -48 V telecom rectifier outputs. IC Role / Device Role / Timing Role: Precision Zener reference with ±5% tolerance and <10 Ω dynamic impedance for accurate threshold detection. Use Value: Enables reliable fault reporting at ±0.5 V accuracy across −40°C to +85°C ambient without calibration drift. |
Use Scenario: Stabilizing high-voltage bias rails (e.g., 39 V for photomultiplier tube anodes) in portable ultrasound units. IC Role / Device Role / Timing Role: Low-noise voltage reference with <0.25 μA leakage ensuring minimal current draw from battery-powered HV supplies. Use Value: Extends single-charge battery life by >12 hours versus higher-leakage alternatives while maintaining 39 V regulation stability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MMSZ5241B-TP | 200 mW SOD-123 package; 36 V nominal Zener; ZZT = 23 Ω @ 20 mA; no AEC-Q101 qualification. | Lower power rating limits use to signal-level clamping only-not suitable for 3 W automotive load dump protection. | Select when space constraints prohibit SMB footprint and power demands are <500 mW. |
| BZX84-C39LT1G | 350 mW SOT-23 package; 39 V nominal; ZZT = 90 Ω @ 5 mA; AEC-Q101 qualified but not PPAP-capable. | Limited surge capability (max 10 W for 1 ms) and higher impedance reduce effectiveness in high-energy transient suppression. | Choose for cost-sensitive consumer electronics where AEC-Q101 is required but full PPAP documentation is not mandated. |
Compared with MMSZ5241B-TP and BZX84-C39LT1G, the SZ1SMB5939BT3G delivers 6× higher power handling, 9× lower dynamic impedance, and full PPAP support-making it the only option for production automotive systems requiring validated process control and 3 W steady-state clamping.
Availability
SZ1SMB5939BT3G is available at Aetrix Electronics and suitable for automotive electronic control units, industrial programmable logic controllers, telecom power monitoring circuits, and medical diagnostic equipment requiring stable component supply with full traceability and lifecycle management.
Supply support for SZ1SMB5939BT3G 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 is a global semiconductor supplier focused on energy-efficient innovation, delivering silicon solutions for automotive, industrial, cloud, and IoT applications with emphasis on functional safety and reliability.
The SZ1SMB59xxT3G series was developed specifically for AEC−Q101-compliant automotive power management, offering robust Zener regulation across 3.3–200 V with enhanced ESD immunity and thermal performance for under-hood deployment.
FAQ
What is the Zener voltage tolerance for SZ1SMB5939BT3G?
The SZ1SMB5939BT3G has a nominal Zener voltage of 39 V with a tolerance of ±5%, meaning its actual breakdown voltage falls between 37.05 V and 40.95 V when measured at IZT = 45 mA and TL = 30°C. This tolerance is confirmed in the Electrical Characteristics table on page 3 of the onsemi datasheet and applies across the full operating temperature range.
Is SZ1SMB5939BT3G suitable for automotive applications?
Yes, SZ1SMB5939BT3G is AEC−Q101 qualified and PPAP capable, with validation for temperature cycling, mechanical shock, and humidity bias per automotive reliability standards. Its Pb-free construction, 16 kV HBM ESD rating, and operation from −65°C to +150°C make it appropriate for engine control units, body modules, and ADAS power domains where robustness is mandatory.
What is the maximum surge power rating for SZ1SMB5939BT3G?
The SZ1SMB5939BT3G supports up to 100 W peak surge power for a 1 ms non-repetitive pulse, as shown in Figure 2 of the onsemi datasheet. This capability allows it to absorb load dump transients in 12 V/42 V automotive systems without failure, provided the pulse repetition rate remains below 0.1 Hz to allow thermal recovery.
How does the thermal resistance of SZ1SMB5939BT3G affect PCB layout?
SZ1SMB5939BT3G has RJA = 226 °C/W on standard FR-4, meaning a 3 W dissipation raises junction temperature by 678°C above ambient-exceeding safe limits. To operate continuously at full power, the PCB must provide ≥25 mm² of 2 oz copper connected to both terminals, verified via thermal simulation or IR imaging per JEDEC JESD51-2.
What is the reverse leakage current specification for SZ1SMB5939BT3G?
The reverse leakage current for SZ1SMB5939BT3G is specified as ≤0.25 μA at VR = 31.2 V (80% of nominal Zener voltage), measured at TL = 30°C. This ultra-low leakage ensures minimal quiescent current draw in battery-backed systems and prevents false triggering in high-impedance sensing circuits.
SZ1SMB5939BT3G Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- DO-214AA, SMB
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 39 V
- Tolerance:
- ±5%
- Power - Max:
- 3 W
- Impedance (Max) (Zzt):
- 45 Ohms
- Current - Reverse Leakage @ Vr:
- 1 µA @ 29.7 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.5 V @ 200 mA
- Operating Temperature:
- -65°C ~ 150°C
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMB
SZ1SMB5939BT3G FAQ
1.How can I place an order for SZ1SMB5939BT3G through Aetrix?
Please submit a Request for Quotation (RFQ) for SZ1SMB5939BT3G 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 SZ1SMB5939BT3G reliable?
The price and inventory of SZ1SMB5939BT3G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SZ1SMB5939BT3G is usually 5 days.
3.What payment methods are accepted for SZ1SMB5939BT3G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SZ1SMB5939BT3G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SZ1SMB5939BT3G?
SZ1SMB5939BT3G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SZ1SMB5939BT3G 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 SZ1SMB5939BT3G?
For technical support, including SZ1SMB5939BT3G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SZ1SMB5939BT3G requirements.
6.How does Aetrix verify that SZ1SMB5939BT3G is sourced from the original manufacturer or authorized distributors?
All SZ1SMB5939BT3G 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 SZ1SMB5939BT3G meets industry standards.
7.What is the process for return or replacement of SZ1SMB5939BT3G?
All SZ1SMB5939BT3G units undergo pre-shipment inspection (PSI). If there is an issue with SZ1SMB5939BT3G, 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 SZ1SMB5939BT3G part is unused and in its original packaging.
Return procedure for SZ1SMB5939BT3G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SZ1SMB5939BT3G 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…
