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onsemi 1SMA45AT3G
- Part No.:
- 1SMA45AT3G
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
1SMA45AT3G.pdf
- Description:
- TVS DIODE 45VWM 72.2VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:25,000
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Product details
Overview
1SMA45AT3G from ON Semiconductor is a unidirectional 400 W peak power Zener transient voltage suppressor (TVS) designed for overvoltage protection of sensitive electronics. It features a 45 V working peak reverse voltage (VRWM), 52.65 V nominal breakdown voltage (VBR) at 1 mA, 72.2 V clamping voltage (VC) at 5.5 A peak pulse current, and sub-1 ns response time - deployed in automotive power supplies and industrial control I/O interfaces.
For engineers reviewing the 1SMA45AT3G datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM ≥ system DC bus voltage, VC margin relative to IC absolute maximum ratings, surge current capability under 10/1000 µs waveform, and SMA package thermal performance on FR-4 PCBs with minimum footprint.
Technical Context
The 1SMA45AT3G operates as a unidirectional Zener-based TVS diode, leveraging avalanche breakdown to clamp transients above its VBR threshold. Its low zener impedance and fast <1 ns response ensure effective suppression of ESD and lightning-induced surges without affecting normal signal integrity.
It is rated for 400 W non-repetitive peak pulse power (10/1000 µs waveform), supports 40 A forward surge current (8.3 ms half-sine), and maintains stable clamping up to +150°C junction temperature - enabling use in under-hood automotive modules and industrial PLC backplanes where thermal derating must be modeled per Figure 3.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 45 V - Maximum continuous reverse operating voltage before clamping begins; must exceed circuit's DC or peak AC rail voltage. |
| VBR @ IT=1 mA | 50–55.3 V - Breakdown range defining turn-on threshold; ensures reliable triggering above system operating voltage. |
| VC @ IPP=5.5 A | 72.2 V - Clamped voltage during 10/1000 µs surge; determines maximum stress imposed on downstream ICs. |
| Peak Pulse Power | 400 W - Sustained for 1 ms per REA 10/1000 µs waveform; defines transient energy handling capacity. |
| Junction Capacitance | 280 pF @ 0 V - Low enough for <100 MHz signal lines; impacts high-speed data line protection feasibility. |
| ESD Rating | Class 3 (>16 kV HBM) - Meets IEC 61000-4-2 Level 4 for system-level ESD immunity design. |
Pinout & Package
1SMA45AT3G uses the SMA (DO-214AC) surface-mount package (Case 403D), featuring a low-profile, flat-handling design suitable for top-side or bottom-side PCB mounting. Polarity is marked by a cathode band; leads are Pb-free and solderable at 260°C for 10 seconds.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (banded end) | Transient current sink node | Connected to protected line; conducts surge current to ground when VLINE exceeds VBR. |
| Anode | Reference/ground return path | Typically tied to system ground plane; completes clamping loop and defines reference potential for VC. |
Key Features
| Feature | Design Value |
|---|---|
| Unidirectional clamping architecture | Enables asymmetric protection on DC-biased lines (e.g., 12 V power rails) without forward conduction during normal operation. |
| 400 W peak pulse rating | Handles automotive load-dump transients (ISO 7637-2 Pulse 5a) and industrial surge events (IEC 61000-4-5) without degradation. |
| Sub-1 ns response time | Clamps ESD events (IEC 61000-4-2) before sensitive logic inputs reach destructive voltage thresholds. |
| SURMETIC® package reliability | Void-free molded plastic construction ensures long-term moisture resistance and thermal cycle stability in harsh environments. |
Applications
| Automotive Power Rail Protection | Industrial PLC Digital I/O Protection |
|---|---|
Use Scenario: Protecting 12 V/24 V battery-fed ECUs from load dump and jump-start transients per ISO 7637-2. IC Role / Device Role / Timing Role: Unidirectional TVS placed between power rail and chassis ground to clamp surges >45 V. Use Value: Limits peak rail voltage to 72.2 V during 400 W transients, preventing damage to MCU power supplies and CAN transceivers. | Use Scenario: Shielding 24 V digital input channels in programmable logic controllers from field-wiring induced surges. IC Role / Device Role / Timing Role: Front-end transient suppressor on optocoupler input side, referenced to isolated logic ground. Use Value: Absorbs 5.5 A surge current while maintaining <72.2 V clamping, preserving optocoupler CMTI and input stage integrity. |
| Medical Equipment Power Supply Input | Telecom Line Card Surge Protection |
Use Scenario: Safeguarding auxiliary 5 V/12 V rails in diagnostic imaging systems against AC line coupling and ESD. IC Role / Device Role / Timing Role: Secondary-stage TVS after primary MOV filtering, providing precise clamping near IC absolute max ratings. Use Value: 280 pF capacitance avoids signal distortion on low-noise analog supply paths while delivering 400 W surge headroom. | Use Scenario: Protecting Ethernet PHY power pins and RS-485 transceiver VCC lines in outdoor base station line cards. IC Role / Device Role / Timing Role: Localized clamping device adjacent to connector entry points, referenced to local ground plane. Use Value: Withstands repeated 10/1000 µs surges up to 400 W and meets Class 3 HBM ESD requirements for field-replaceable modules. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SZ1SMA45AT3G | AEC-Q101 qualified; identical electrical specs; automotive-grade traceability and PPAP support. | Required for automotive OEM designs requiring certified components and process control documentation. | Select SZ1SMA45AT3G when automotive qualification, site-specific change control, or PPAP submission is mandatory. |
| 1SMA45AHE3_A/H | VBR min/max tighter (50.0–55.0 V); same VRWM/VC; Vishay packaging with alternate marking. | Drop-in replacement in non-automotive industrial designs where second-source assurance is needed. | Choose 1SMA45AHE3_A/H for dual-sourcing flexibility without layout or BOM revision. |
Compared with 1SMA45AT3G, SZ1SMA45AT3G adds automotive qualification overhead but no electrical trade-offs, while 1SMA45AHE3_A/H offers identical clamping performance with alternate supply chain validation - both require no PCB changes but differ in compliance scope and sourcing origin.
Availability
1SMA45AT3G is available at Aetrix Electronics and suitable for automotive power rail protection, industrial PLC I/O hardening, and medical equipment power supply input stages requiring stable component supply across multi-year production cycles.
Supply support for 1SMA45AT3G 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
ON Semiconductor is a global semiconductor manufacturer specializing in power management, analog, sensor, and discrete devices for automotive, industrial, and communications markets.
The 1SMAxxAT3G series was developed to deliver high-energy transient suppression in compact surface-mount packages for cost-sensitive, high-reliability applications including automotive electronics and industrial controls.
FAQ
What is the clamping voltage of the 1SMA45AT3G under a 5.5 A transient?
The 1SMA45AT3G has a maximum clamping voltage (VC) of 72.2 V when subjected to a 5.5 A peak pulse current (IPP) under the standard 10/1000 µs waveform. This value is measured at TA = 25°C and defines the upper voltage limit imposed on protected circuitry during surge events - critical for ensuring downstream ICs remain within their absolute maximum ratings. The 1SMA45AT3G achieves this clamping performance while dissipating 400 W peak power.
Is the 1SMA45AT3G suitable for bidirectional signal line protection?
No, the 1SMA45AT3G is a unidirectional TVS diode and is not suitable for bidirectional signal line protection such as RS-485 or USB data lines. It conducts only in reverse bias above its breakdown voltage and blocks forward current beyond ~3.5 V. For bidirectional protection, ON Semiconductor offers the 1SMA45CAT3G variant (not the 1SMA45AT3G), which provides symmetrical clamping in both polarities. Using 1SMA45AT3G on AC-coupled or differential lines risks forward conduction and failure.
What is the thermal resistance from junction to ambient for the 1SMA45AT3G?
The 1SMA45AT3G has a thermal resistance from junction to ambient (RJA) of 250°C/W when mounted on an FR-4 board using ON Semiconductor's minimum recommended footprint. At TA = 25°C, this yields a maximum DC power dissipation of 0.5 W; derating is required above 25°C at 4.0 mW/°C. For higher power handling, thermal relief via copper pour or heatsinking is necessary - the 1SMA45AT3G's RJL of 50°C/W (junction-to-lead) supports improved conduction when leads are soldered to large copper areas.
Does the 1SMA45AT3G meet automotive qualification standards?
The standard 1SMA45AT3G is not AEC-Q101 qualified; however, its automotive-grade counterpart SZ1SMA45AT3G is fully AEC-Q101 qualified and PPAP capable. Both share identical electrical specifications (VRWM = 45 V, VC = 72.2 V, PPK = 400 W), but only SZ1SMA45AT3G undergoes extended stress testing, lot traceability, and change control required for automotive Tier 1 supply. For non-automotive industrial or medical use, 1SMA45AT3G remains fully compliant with its published ratings.
How does the junction capacitance of the 1SMA45AT3G affect high-speed circuit design?
The 1SMA45AT3G exhibits a typical junction capacitance of 280 pF at 0 V bias, which may load high-speed signal lines and cause edge degradation or timing skew if placed directly on data paths above ~10 MHz. It is best suited for power rail and low-frequency I/O protection (e.g., 24 V digital inputs, relay drivers). For USB, Ethernet, or CAN FD lines, lower-capacitance TVS devices (<100 pF) are recommended - the 1SMA45AT3G should be used only on DC-biased or low-bandwidth nodes where 280 pF introduces negligible impedance mismatch.
1SMA45AT3G Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- DO-214AC, SMA
- Series:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 45V
- Voltage - Breakdown (Min):
- 50V
- Voltage - Clamping (Max) @ Ipp:
- 72.2V
- Current - Peak Pulse (10/1000µs):
- 5.5A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- 280pF @ 1MHz
- Operating Temperature:
- -65°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMA
1SMA45AT3G FAQ
1.How can I place an order for 1SMA45AT3G through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMA45AT3G 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 1SMA45AT3G reliable?
The price and inventory of 1SMA45AT3G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMA45AT3G is usually 5 days.
3.What payment methods are accepted for 1SMA45AT3G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMA45AT3G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMA45AT3G?
1SMA45AT3G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMA45AT3G 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 1SMA45AT3G?
For technical support, including 1SMA45AT3G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMA45AT3G requirements.
6.How does Aetrix verify that 1SMA45AT3G is sourced from the original manufacturer or authorized distributors?
All 1SMA45AT3G 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 1SMA45AT3G meets industry standards.
7.What is the process for return or replacement of 1SMA45AT3G?
All 1SMA45AT3G units undergo pre-shipment inspection (PSI). If there is an issue with 1SMA45AT3G, 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 1SMA45AT3G part is unused and in its original packaging.
Return procedure for 1SMA45AT3G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1SMA45AT3G Tags
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