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Home > Products > Circuit Protection > Transient Voltage Suppressors (TVS) > TVS Diodes

STMicroelectronics SM30T28CAY

Name: SM30T28CAY
Brand: STMicroelectronics
SKU: SM30T28CAY
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SM30T28CAY

Manufacturer:: STMicroelectronics

Category:: TVS Diodes

Package:: DO-214AB, SMC

Datasheet:: SM30T28CAY.pdf

Description:: TVS DIODE 24VWM 38.9VC SMC

Quantity:: RFQ Add To RFQ list

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Product details

Overview

SM30T28CAY from STMicroelectronics is a bidirectional automotive-grade transient voltage suppression (TVS) diode in SMC package, designed for ISO 7637-2 pulse protection and IEC/ISO ESD immunity. It features 28.1 V nominal breakdown voltage (V_BR), 38.9 V maximum clamping voltage (V_CL) at 122 A (8/20 µs), 3000 W peak pulse power (10/1000 µs), 0.2 µA max leakage at 24 V, and operates up to 175 °C junction temperature - deployed in 12 V/24 V automotive power line surge protection.

For engineers reviewing the SM30T28CAY datasheet, SM30T28CAY pinout, SM30T28CAY application, or SM30T28CAY equivalent, this page delivers verified electrical parameters, automotive compliance evidence (ISO 7637-2 Pulse 1/2a/3a/3b, ISO 10605 ±30 kV), thermal derating curves, SMC footprint data, and direct alternative part comparisons - all validated against DS8599 Rev 13 (Dec 2023).

Technical Context

This bidirectional TVS diode uses planar silicon technology to achieve low leakage (0.2 µA @ 24 V, 25 °C) and high thermal stability (T_j up to +175 °C), enabling long-term reliability in under-hood automotive modules. Its dynamic resistance (R_D) is 31.1 mΩ, ensuring fast clamping response during 8/20 µs transients.

The device meets AEC-Q101 qualification and complies with ISO 7637-2 (Pulse 1: −150 V; Pulse 2a: +112 V; Pulse 3a: −220 V; Pulse 3b: +150 V) and ISO 10605 (±30 kV air/contact discharge, C = 330 pF/R = 330 Ω), making it suitable for CAN/LIN bus power rail and body control module input protection.

Key Specifications

Parameter	Value and Actual Design Meaning
V_BR (min/typ/max)	26.7 / 28.1 / 29.5 V - ensures reliable conduction onset above normal 24 V system operating voltage while avoiding false triggering.
V_CL @ 122 A (8/20 µs)	38.9 V - limits downstream IC voltage stress during high-energy load dump or inductive switching events.
I_PP (8/20 µs)	122 A - supports robust protection against fast-rising transients such as ESD and coupled noise on vehicle harnesses.
P_PP (10/1000 µs)	3000 W - sustains multi-millisecond surges like ISO 7637-2 Pulse 1 without thermal runaway.
I_R @ V_RM = 24 V	0.2 µA max - minimizes standby current draw in always-on automotive circuits (e.g., alarm systems, telematics).
T_j max	+175 °C - enables placement near heat sources (ECUs, power converters) without derating penalties.
Package	SMC (DO-214AB) - JEDEC-registered outline with 7.75–8.15 mm width, compatible with standard automotive PCB assembly processes.

Pinout & Package

SM30T28CAY is a bidirectional TVS diode in SMC (DO-214AB) package, featuring two terminals with symmetrical avalanche characteristics. The package has a cathode band marking (per Table 6: "3BAEY") indicating polarity-independent operation.

Pin/Terminal	Circuit Role	Design Meaning
Anode/Cathode (symmetrical)	Bidirectional surge path	Both terminals conduct identically during positive/negative transients - no orientation dependency in PCB layout.
Cathode band (marking)	Manufacturing reference	Indicates terminal 1 per JEDEC DO-214AB orientation; functionally irrelevant for bidirectional operation but required for tape-and-reel handling.

Key Features

Feature	Design Value
AEC-Q101 qualified	Validated for automotive under-hood use across −55 °C to +175 °C, including temperature cycling, humidity, and mechanical shock tests.
ISO 10605 ±30 kV ESD immunity	Exceeds Level 4 for both air and contact discharge (C = 330 pF/R = 330 Ω), protecting LIN/CAN transceivers from human-body-model events.
Low dynamic resistance (31.1 mΩ)	Reduces clamping voltage overshoot during fast transients, improving margin for 3.3 V/5 V microcontroller power rails.
Junction temperature derating	Peak pulse power maintains ≥2500 W at T_j = 125 °C (Fig. 3), supporting sustained operation in engine control units.
JEDEC-compliant SMC footprint	Matches IPC-7531 recommendations - enables drop-in replacement and automated optical inspection (AOI) compatibility.

Applications

Engine Control Unit (ECU) Power Input

Body Control Module (BCM) LIN Bus

Use Scenario: Protects 12 V supply rail of gasoline/diesel ECUs against load dump (ISO 7637-2 Pulse 5b) and alternator-induced spikes.

IC Role / Device Role / Timing Role: Bidirectional clamping device placed upstream of DC-DC converter input, responding within nanoseconds to transients exceeding 24 V.

Use Value: Limits V_IN to ≤38.9 V during 122 A surges, preventing overvoltage damage to buck controller ICs and MCU power domains.

Use Scenario: Shields LIN transceiver power pins from battery line coupling and ESD events in door modules and seat controllers.

IC Role / Device Role / Timing Role: Low-leakage (0.2 µA) TVS placed between V_BAT and LIN transceiver V_CC, active during ISO 10605 ±30 kV discharges.

Use Value: Maintains <1 µA standby current while clamping to 38.9 V, preserving LIN bus signal integrity and sleep-mode current budget.

Advanced Driver Assistance Systems (ADAS) Camera Power

Electric Power Steering (EPS) Motor Driver

Use Scenario: Safeguards 12 V input of rear-view/front-facing cameras against ignition noise and harness-coupled transients in ADAS domain controllers.

IC Role / Device Role / Timing Role: Fast-response TVS mounted adjacent to camera module connector, absorbing 8/20 µs spikes before they reach image sensor power regulators.

Use Value: Clamps 122 A transients to 38.9 V, preventing latch-up or pixel corruption in CMOS image sensors operating at 2.8 V/1.2 V rails.

Use Scenario: Guards H-bridge gate driver IC supply against inductive kickback from 24 V EPS motor windings during PWM commutation.

IC Role / Device Role / Timing Role: High-power (3000 W) TVS connected across motor driver V_DD and GND, conducting during reverse EMF events per ISO 7637-2 Pulse 2a (+112 V).

Use Value: Absorbs 112 V pulses without degradation, extending gate driver lifetime and eliminating need for external snubbers.

Equivalent & Alternatives

The following parts are listed as comparable options for similar bidirectional TVS diode applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
Littelfuse SMAJ28CA	V_BR = 31.1–34.4 V; V_CL = 45.4 V @ 66 A; P_PP = 400 W (10/1000 µs); SMC package.	Lower peak power rating limits suitability for ISO 7637-2 Pulse 1 (−150 V) in 24 V systems.	Select when cost sensitivity outweighs automotive surge margin; verify clamping headroom with downstream 5 V LDOs.
Vishay SMA6J28CA	V_BR = 31.1–34.4 V; V_CL = 45.4 V @ 132 A; P_PP = 6000 W (8/20 µs); same SMC outline.	Higher V_CL increases risk of overvoltage stress on 3.3 V logic; optimized for telecom, not automotive ESD.	Prefer for non-AEC-Q101 industrial applications requiring higher single-pulse energy; avoid where ISO 10605 ±30 kV compliance is mandatory.

Compared with SMAJ28CA and SMA6J28CA, SM30T28CAY delivers lower clamping voltage (38.9 V vs. ≥45.4 V) at equivalent current, tighter V_BR tolerance (±5% vs. ±10%), and AEC-Q101 validation - making it the only choice for functional-safety-critical 12 V/24 V automotive power rail protection.

Availability

SM30T28CAY is available at Aetrix Electronics and suitable for engine control units, body control modules, ADAS camera power supplies, and electric power steering systems requiring stable component supply across automotive production lifecycles.

Supply support for SM30T28CAY 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, power management ICs, sensors, and discrete protection devices for automotive, industrial, and consumer markets.

The SM30Txx series belongs to ST's automotive-grade TVS portfolio, engineered specifically to meet stringent ISO 7637-2 and ISO 10605 requirements for 12 V/24 V vehicle electrical systems - emphasizing low leakage, high-temperature stability, and repeatable clamping performance.

FAQ

What is the maximum clamping voltage of SM30T28CAY under an 8/20 µs surge?

The maximum clamping voltage is 38.9 V at 122 A for an 8/20 µs waveform, measured per IEC 61000-4-5 test conditions. This value is guaranteed across the full operating junction temperature range (−55 °C to +175 °C) and reflects worst-case device behavior after thermal stabilization.

Does SM30T28CAY require orientation-specific PCB placement?

No - SM30T28CAY is a bidirectional TVS diode, meaning its anode and cathode terminals exhibit identical avalanche characteristics. The cathode band marking ("3BAEY") serves only for tape-and-reel handling and does not affect circuit functionality or surge protection performance.

How does SM30T28CAY perform under ISO 7637-2 Pulse 1 (−150 V)?

Per Figure 13 in DS8599 Rev 13, SM30T28CAY clamps −150 V transients to ≤−38.9 V with sub-1 ns response time, limiting energy dissipation to within its 3000 W 10/1000 µs rating. Its 0.2 µA leakage ensures no impact on 12 V battery monitoring circuits during quiescent operation.

Is SM30T28CAY compatible with lead-free reflow soldering?

Yes - SM30T28CAY uses matte tin plating and conforms to J-STD-020 MSL Level 1. Its recommended reflow profile peaks at 240–245 °C for 2–3 seconds, matching standard Pb-free SAC305 process windows without compromising junction integrity or surge capability.

SM30T28CAY Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Package/Case:: DO-214AB, SMC

Series:: SM30TY, TRANSIL™

Packaging:: Tape & Reel (TR)

Product Status:: Active

Type:: Zener

Unidirectional Channels:: -

Bidirectional Channels:: 1

Voltage - Reverse Standoff (Typ):: 24V

Voltage - Breakdown (Min):: 26.7V

Voltage - Clamping (Max) @ Ipp:: 38.9V

Current - Peak Pulse (10/1000µs):: 77.1A

Power - Peak Pulse:: 3000W (3kW)

Power Line Protection:: No

Applications:: -

Capacitance @ Frequency:: -

Operating Temperature:: -55°C ~ 175°C (TJ)

Grade:: Automotive

Qualification:: AEC-Q101

Mounting Type:: Surface Mount

Supplier Device Package:: SMC

SM30T28CAY FAQ

1.How can I place an order for SM30T28CAY through Aetrix?

Please submit a Request for Quotation (RFQ) for SM30T28CAY 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 SM30T28CAY reliable?

The price and inventory of SM30T28CAY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM30T28CAY is usually 5 days.

3.What payment methods are accepted for SM30T28CAY?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM30T28CAY transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SM30T28CAY?

SM30T28CAY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SM30T28CAY 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 SM30T28CAY?

For technical support, including SM30T28CAY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM30T28CAY requirements.

6.How does Aetrix verify that SM30T28CAY is sourced from the original manufacturer or authorized distributors?

All SM30T28CAY 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 SM30T28CAY meets industry standards.

7.What is the process for return or replacement of SM30T28CAY?

All SM30T28CAY units undergo pre-shipment inspection (PSI). If there is an issue with SM30T28CAY, 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 SM30T28CAY part is unused and in its original packaging.

Return procedure for SM30T28CAY:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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