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onsemi 1SMB5955BT3
- Part No.:
- 1SMB5955BT3
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
1SMB5955BT3.pdf
- Description:
- DIODE ZENER 180V 3W SMB
- Quantity:
- Payment:
- Shipping:
Inventory:9,770
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Product details
Overview
1SMB5955BT3 from onsemi is a 3 W surface-mount Zener diode with nominal zener voltage of 180 V, maximum zener impedance of 2.1 Ω at 900 mA test current, and reverse leakage current ≤0.25 μA at 144 V, designed for precision voltage regulation and overvoltage protection in industrial power supplies and DC-DC converter feedback loops.
For engineers reviewing the 1SMB5955BT3 datasheet, pinout, applications, or equivalent options, key selection criteria include its ±5% zener tolerance, 136.8 A maximum DC zener current, 226 °C/W junction-to-ambient thermal resistance, and SMB (Case 403A) package compatibility with automated SMT assembly.
Technical Context
The 1SMB5955BT3 operates as a single-junction silicon Zener diode optimized for stable DC voltage reference and transient clamping. Its 180 V nominal breakdown voltage is specified at IZT = 900 mA with thermal equilibrium at TL = 30°C, and it maintains low dynamic impedance (2.1 Ω) under rated test conditions.
It features an ESD rating >16 kV per Human Body Model, Pb-free SMB plastic package (UL 94 V-0), and AEC-Q101 qualification for automotive-grade reliability. The cathode is marked by a polarity band, and the modified L-bend leads ensure robust solder joint formation on FR-4 PCBs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 171–189 V (±5% tolerance; nominal 180 V at IZT = 900 mA) |
| Max Power Dissipation | 3.0 W @ TL = 75°C; derates to 550 mW @ TA = 25°C |
| Zener Impedance (ZZT) | 2.1 Ω max @ IZT = 900 mA - ensures tight regulation under load |
| Reverse Leakage Current | ≤0.25 μA @ VR = 144 V - critical for low-power standby circuits |
| Max DC Zener Current (IZM) | 136.8 A - defines absolute safe operating current limit |
| Junction-to-Ambient RJA | 226 °C/W - determines thermal rise in standard FR-4 layout |
| Operating Temperature | −65°C to +150°C - supports extended industrial and automotive environments |
Pinout & Package
SMB (Case 403A) surface-mount plastic package with cathode indicated by polarity band; dimensions: 4.32 mm × 3.56 mm × 2.20 mm (L × W × H); lead finish is readily solderable; UL 94 V-0 flammability rating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / Zener cathode reference ground | Connected to circuit ground or lower-potential node during reverse-bias operation |
| Cathode | Zener breakdown terminal / voltage reference output | Provides regulated 180 V reference when reverse-biased above VZ; marked by band |
Key Features
| Feature | Design Value |
|---|---|
| ESD Robustness | Class 3 (>16 kV HBM) - enables handling in unshielded production environments without damage |
| Pb-Free Construction | RoHS-compliant SMB package - meets global environmental compliance requirements |
| Thermal Performance | 40 °C/W junction-to-lead resistance - supports high-power dissipation with minimal board-level heatsinking |
| Mounting Flexibility | Flat handling surface and dual-side mounting capability - accommodates top- or bottom-side PCB assembly |
| Stability Under Load | Low ZZK = 7000 Ω @ IZK = 1 mA - maintains regulation even near knee voltage |
Applications
| Industrial Power Supply Regulation | Automotive DC-DC Converter Feedback |
|---|---|
Use Scenario: Primary-side overvoltage clamp in 48 V telecom rectifier modules. IC Role / Device Role / Timing Role: Zener diode providing precise 180 V shunt regulation to protect downstream MOSFETs and controllers. Use Value: Prevents catastrophic failure during line surges by clamping at 189 V max, leveraging 3 W steady-state power rating. |
Use Scenario: Reference voltage source in isolated flyback controller feedback network for 12 V automotive infotainment supply. IC Role / Device Role / Timing Role: Stable 180 V zener reference enabling accurate optocoupler biasing and loop stability. Use Value: ±5% tolerance and <0.25 μA leakage ensure consistent regulation across −40°C to +125°C ambient range. |
| High-Voltage Sensor Biasing | Test Equipment Protection Circuitry |
Use Scenario: Biasing resistor divider for 200 V-range analog front-end in portable insulation testers. IC Role / Device Role / Timing Role: Precision voltage reference stabilizing high-impedance measurement path against supply variation. Use Value: Low 2.1 Ω ZZT minimizes loading error on 10 MΩ input impedance circuits. |
Use Scenario: Input-stage transient suppressor in benchtop multimeter high-voltage input channel. IC Role / Device Role / Timing Role: Fast-response overvoltage clamp protecting ADC input and internal reference. Use Value: 136.8 A IZM and 3 W rating withstand 10/1000 μs surge pulses up to 7 kW peak power. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N5955B | Same 180 V nominal VZ, but DO-41 through-hole package; higher RJA (500 °C/W) | Requires manual or wave-solder assembly; unsuitable for high-density SMT layouts | Select only if legacy through-hole design or prototyping with breadboard use is required |
| SZ1SMB5955BT3G | Identical electrical specs and SMB package; "G" suffix denotes certified Pb-free compliance per J-STD-609 | No functional difference; preferred for automotive PPAP submissions requiring full material traceability | Choose SZ1SMB5955BT3G for AEC-Q101-certified production programs with strict RoHS documentation |
Compared with 1SMB5955BT3, 1N5955B requires PCB redesign for through-hole mounting and offers inferior thermal performance, while SZ1SMB5955BT3G provides identical functionality with enhanced compliance documentation-making it the drop-in replacement for automotive-grade builds.
Availability
1SMB5955BT3 is available at Aetrix Electronics and suitable for industrial power supplies, automotive DC-DC converters, high-voltage sensor systems, and test equipment requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for 1SMB5955BT3 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 1SMB5955BT3 belongs to the 1SMB59xxBT3 series of 3 W surface-mount Zener regulators, engineered for high-reliability voltage reference and overvoltage protection in space-constrained, thermally demanding applications.
FAQ
What is the zener voltage tolerance for 1SMB5955BT3?
The 1SMB5955BT3 has a ±5% zener voltage tolerance, meaning its reverse breakdown voltage ranges from 171 V to 189 V at IZT = 900 mA and TL = 30°C. This tolerance is explicitly defined in the Electrical Characteristics table on page 3 of the official datasheet and applies to all units within the 1SMB59xxBT3 family.
Can 1SMB5955BT3 be used in automotive applications?
Yes, the 1SMB5955BT3 is AEC-Q101 qualified and PPAP capable when ordered as SZ1SMB5955BT3G (Pb-free variant). While the base 1SMB5955BT3 part meets the same electrical and mechanical specifications, the "SZ" prefix and "G" suffix denote full automotive qualification with controlled site and change management-required for Tier 1 automotive production.
What is the maximum surge power rating for 1SMB5955BT3?
The 1SMB5955BT3 supports nonrepetitive peak surge power up to 7 kW for 10/1000 μs waveform at TJ = 25°C, as shown in Figure 2 of the datasheet. This rating enables robust transient suppression in power supply input stages without requiring external TVS devices.
How does the thermal resistance of 1SMB5955BT3 affect PCB layout?
The 1SMB5955BT3 has RJA = 226 °C/W on FR-4 board, so at full 3 W dissipation, junction temperature rises ~678°C above ambient-exceeding safe limits. Therefore, PCB layout must include copper pour under the SMB pad and minimize trace length to leverage its lower RJL = 40 °C/W for lead-to-board heat transfer.
Is 1SMB5955BT3 compatible with lead-free reflow soldering?
Yes, the 1SMB5955BT3 is rated for lead-free reflow with maximum lead temperature of 260°C for 10 seconds, matching IPC/JEDEC J-STD-020 requirements. Its void-free transfer-molded plastic case and corrosion-resistant leads ensure reliable solder joint formation using standard SAC305 profiles.
1SMB5955BT3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- DO-214AA, SMB
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Voltage - Zener (Nom) (Vz):
- 180 V
- Tolerance:
- ±5%
- Power - Max:
- 3 W
- Impedance (Max) (Zzt):
- 900 Ohms
- Current - Reverse Leakage @ Vr:
- 1 µA @ 136.8 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.5 V @ 200 mA
- Operating Temperature:
- -65°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMB
1SMB5955BT3 FAQ
1.How can I place an order for 1SMB5955BT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMB5955BT3 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 1SMB5955BT3 reliable?
The price and inventory of 1SMB5955BT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMB5955BT3 is usually 5 days.
3.What payment methods are accepted for 1SMB5955BT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMB5955BT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMB5955BT3?
1SMB5955BT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMB5955BT3 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 1SMB5955BT3?
For technical support, including 1SMB5955BT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMB5955BT3 requirements.
6.How does Aetrix verify that 1SMB5955BT3 is sourced from the original manufacturer or authorized distributors?
All 1SMB5955BT3 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 1SMB5955BT3 meets industry standards.
7.What is the process for return or replacement of 1SMB5955BT3?
All 1SMB5955BT3 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMB5955BT3, 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 1SMB5955BT3 part is unused and in its original packaging.
Return procedure for 1SMB5955BT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1SMB5955BT3 Tags
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