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onsemi SZ1SMA5945BT3G
- Part No.:
- SZ1SMA5945BT3G
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SZ1SMA5945BT3G.pdf
- Description:
- DIODE ZENER 68V 1.5W SMA
- Quantity:
- Payment:
- Shipping:
Inventory:9,515
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Product details
Overview
SZ1SMA5945BT3G from onsemi is a 1.5 W surface-mount Zener diode with nominal zener voltage of 68 V, maximum zener impedance of 1700 Ω at 120 mA test current, and reverse leakage current ≤0.25 μA at 51.7 V. It operates across −65 °C to +150 °C and is AEC−Q101 qualified for automotive applications requiring stable voltage regulation in power supply rails and overvoltage protection circuits.
For engineers reviewing the SZ1SMA5945BT3G datasheet, pinout, applications, or equivalent options, key selection criteria include its 68 V ±5% zener tolerance, low-profile SMA package, 16 kV HBM ESD rating, and suitability for precision reference and clamping in automotive ECUs and industrial power converters.
Technical Context
This device functions as a two-terminal voltage reference and clamping element, operating in reverse breakdown mode with specified zener voltage (VZ) measured at IZT = 120 mA. Its thermal resistance junction-to-lead is 50 °C/W, enabling 1.5 W dissipation at TL = 75 °C with defined derating above that temperature.
The SZ1SMA5945BT3G exhibits a positive temperature coefficient typical of higher-voltage Zeners, with θVZ ≈ +10 mV/°C near 68 V (per Figure 6), and maintains <0.25 μA leakage at VR = 51.7 V - 75% of nominal VZ. It is not intended for forward conduction; VF ≤ 1.2 V is specified only at IF = 200 mA for polarity verification.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 64.6 V min / 68 V nom / 71.4 V max @ IZT = 120 mA - defines regulated output voltage window under standard test conditions |
| Zener Impedance (ZZT) | 1700 Ω max @ IZT = 120 mA - indicates voltage regulation stability under dynamic load changes |
| Reverse Leakage Current (IR) | ≤0.25 μA @ VR = 51.7 V - ensures minimal standby power loss in high-impedance bias networks |
| Power Dissipation (PD) | 1.5 W @ TL = 75 °C - requires thermal pad design per onsemi's recommended footprint for reliable operation |
| ESD Rating | Class 3 (>16 kV) per HBM - supports robust handling in automated SMT assembly without additional ESD mitigation |
| Operating Temperature | −65 °C to +150 °C - validated for under-hood automotive environments and industrial control cabinets |
Pinout & Package
Package: SMA (Case 403D), surface-mount, low-profile plastic package with flat handling surface and molded cathode band. Cathode marked by band; anode is unmarked terminal.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (Band End) | High-side connection in reverse-bias configuration | Connected to regulated node or voltage rail; must be held at higher potential than anode during regulation |
| Anode (Unmarked End) | Low-side connection in reverse-bias configuration | Typically tied to ground or return path; establishes reference point for zener voltage drop |
Key Features
| Feature | Design Value |
|---|---|
| AEC−Q101 qualification | Validated for automotive electronics including engine control modules and body controllers where reliability under thermal cycling and vibration is mandatory |
| 16 kV HBM ESD rating | Eliminates need for external ESD protection during board handling and reflow, reducing BOM count in space-constrained designs |
| ±5% zener voltage tolerance | Enables use in applications requiring tighter regulation than general-purpose Zeners (e.g., feedback dividers in isolated DC/DC converters) |
| Low-profile SMA package | Offers 2.5 mm height and 4.5 mm length - direct replacement for MELF diodes while enabling automated pick-and-place with standard feeders |
| Pb-free construction | Complies with RoHS Directive 2011/65/EU and JEDEC J-STD-020 moisture sensitivity level (MSL) 1 rating for unlimited floor life |
Applications
| Automotive Engine Control Unit (ECU) | Industrial DC/DC Converter Feedback |
|---|---|
Use Scenario: Voltage clamping on 12 V battery-sensed input lines subject to load dump transients up to 40 V. IC Role / Device Role / Timing Role: Standalone overvoltage clamp protecting microcontroller I/O and analog sensor inputs. Use Value: Withstands 1.5 W surge energy and maintains <0.25 μA leakage at 51.7 V, preventing false triggering during normal operation. |
Use Scenario: Precision voltage reference in optocoupler-based feedback loop of 48 V to 5 V isolated flyback converter. IC Role / Device Role / Timing Role: Zener reference setting secondary-side error amplifier threshold. Use Value: 68 V ±5% tolerance and 1700 Ω ZZT ensure stable regulation across line/load variations and temperature extremes. |
| Telecom Power Supply Monitoring | Medical Diagnostic Equipment Biasing |
Use Scenario: Overvoltage detection in -48 V telecom rectifier output monitoring circuit. IC Role / Device Role / Timing Role: Reference element in comparator-based shutdown circuit triggered above −55 V. Use Value: Stable 68 V breakdown with <0.25 μA leakage at 51.7 V enables accurate trip-point setting without drift-induced false alarms. |
Use Scenario: High-stability bias voltage generation for photodiode amplifier stages in portable ultrasound units. IC Role / Device Role / Timing Role: Passive voltage reference establishing DC offset in analog front-end signal chain. Use Value: AEC−Q101 qualification and −65 °C to +150 °C range support operation in thermally demanding medical enclosures with no derating required. |
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-C68LT1G | 0.3 W rating, SOT-23 package, 64.6–71.4 V range, 100 Ω ZZT @ 5 mA - lower power, lower impedance, but not AEC−Q101 qualified | Suitable for low-power consumer electronics; insufficient for automotive load-dump clamping or industrial 1.5 W continuous dissipation | Select only for space-constrained, non-automotive designs where 68 V reference is needed at <100 mW average power. |
| 1N4748A | 1 W rating, DO-41 through-hole package, 63–73 V range, 100 Ω ZZT @ 31 mA - higher impedance at rated current, no AEC−Q101, no Pb-free guarantee | Requires manual or wave soldering; unsuitable for automated SMT production or automotive PPAP compliance | Choose only for legacy through-hole prototyping or repair where SMA footprint compatibility is not required. |
Compared with BZX84-C68LT1G and 1N4748A, the SZ1SMA5945BT3G delivers automotive-grade reliability, surface-mount scalability, and 1.5 W continuous power handling - making it the sole option among the three qualified for AEC−Q101-compliant production and capable of sustained clamping in high-energy transient scenarios.
Availability
SZ1SMA5945BT3G is available at Aetrix Electronics and suitable for automotive ECU protection, industrial DC/DC converter feedback, and telecom power monitoring requiring stable component supply, full traceability, and long-term lifecycle support.
Supply support for SZ1SMA5945BT3G 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, and cloud infrastructure markets.
The SZ1SMA59xxBT3G series was designed specifically for automotive and high-reliability industrial applications requiring AEC−Q101 qualification, robust ESD immunity, and stable zener regulation in compact surface-mount packages.
FAQ
What is the exact zener voltage tolerance for SZ1SMA5945BT3G?
The SZ1SMA5945BT3G has a zener voltage tolerance of ±5%, with minimum, nominal, and maximum values of 64.6 V, 68 V, and 71.4 V respectively, all guaranteed at IZT = 120 mA and thermal equilibrium. This tolerance is explicitly stated in the datasheet's Electrical Characteristics table and applies to all devices in the SZ1SMA59xxBT3G family.
Is SZ1SMA5945BT3G suitable for automotive applications?
Yes, SZ1SMA5945BT3G is AEC−Q101 qualified and PPAP capable, with explicit automotive qualification noted in the datasheet features and ordering information. Its −65 °C to +150 °C operating range, 16 kV HBM ESD rating, and Pb-free construction meet core requirements for engine control, body electronics, and ADAS subsystems.
What is the maximum continuous power dissipation for SZ1SMA5945BT3G?
The SZ1SMA5945BT3G is rated for 1.5 W DC power dissipation at lead temperature (TL) = 75 °C, with derating of 20 mW/°C above that temperature. At ambient temperature (TA) = 25 °C, the rating drops to 0.5 W due to higher thermal resistance junction-to-ambient (250 °C/W).
Does SZ1SMA5945BT3G have a specified forward voltage?
Yes, the SZ1SMA5945BT3G has a maximum forward voltage (VF) of 1.2 V at forward current (IF) = 200 mA, as confirmed in the Electrical Characteristics table. This parameter is provided for polarity verification and is not intended for forward conduction operation.
What is the reverse leakage current specification for SZ1SMA5945BT3G?
The reverse leakage current (IR) for SZ1SMA5945BT3G is specified as ≤0.25 μA at reverse voltage (VR) = 51.7 V, which equals 75% of the nominal zener voltage. This value is measured at TA = 25 °C and appears in the Electrical Characteristics table on page 2 of the datasheet.
SZ1SMA5945BT3G Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- SZ1SMA59xxBT3G
- Package/Case:
- DO-214AC, SMA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 68 V
- Tolerance:
- ±5%
- Power - Max:
- 1.5 W
- Impedance (Max) (Zzt):
- 120 Ohms
- Current - Reverse Leakage @ Vr:
- 500 nA @ 51.7 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.2 V @ 200 mA
- Operating Temperature:
- -65°C ~ 150°C
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMA
SZ1SMA5945BT3G FAQ
1.How can I place an order for SZ1SMA5945BT3G through Aetrix?
Please submit a Request for Quotation (RFQ) for SZ1SMA5945BT3G 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 SZ1SMA5945BT3G reliable?
The price and inventory of SZ1SMA5945BT3G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SZ1SMA5945BT3G is usually 5 days.
3.What payment methods are accepted for SZ1SMA5945BT3G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SZ1SMA5945BT3G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SZ1SMA5945BT3G?
SZ1SMA5945BT3G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SZ1SMA5945BT3G 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 SZ1SMA5945BT3G?
For technical support, including SZ1SMA5945BT3G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SZ1SMA5945BT3G requirements.
6.How does Aetrix verify that SZ1SMA5945BT3G is sourced from the original manufacturer or authorized distributors?
All SZ1SMA5945BT3G 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 SZ1SMA5945BT3G meets industry standards.
7.What is the process for return or replacement of SZ1SMA5945BT3G?
All SZ1SMA5945BT3G units undergo pre-shipment inspection (PSI). If there is an issue with SZ1SMA5945BT3G, 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 SZ1SMA5945BT3G part is unused and in its original packaging.
Return procedure for SZ1SMA5945BT3G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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