onsemi MMT05A310T3

Overview

MMT05A310T3 from onsemi is a bidirectional thyristor surge protective device (TSPD) designed for secondary overvoltage protection in telecom line interfaces. It features 365 V breakover voltage (typ), 50 A 10×1000 µs surge current rating, 270 V off-state voltage maximum, and fails short-circuit under overstress-enabling robust lightning and induction surge protection in customer-premises telecom equipment.

For engineers reviewing the MMT05A310T3 datasheet, pinout, applications, or equivalent options, key selection criteria include bidirectional clamping behavior, dv/dt immunity (2000 V/µs), holding current (340 mA typ), low capacitance (≤50 pF), and UL registration (E210057) for telecom compliance.

Technical Context

The MMT05A310T3 operates as a crowbar-type protector: it remains high-impedance until transient voltage exceeds its bidirectional breakover threshold (365 V typ), then latches on with low on-state voltage (≤3.0 V at 1 A) until surge current falls below holding current (340 mA typ). Its fail-safe short-circuit mode prevents continued unprotected operation after overstress.

Engineered for telecom secondary protection, it meets Telcordia GR-1089, ITU-T K.20/K.21, IEC 60950, and FCC Part 68 requirements. Thermal limits include −40°C to +125°C operating range and +175°C max conducting-junction temperature, with 2000 W peak pulse power dissipation at 50 A/10×1000 µs.

Key Specifications

Pinout & Package

MMT05A310T3 uses the SMA (DO-214AC) surface-mount package (Case 403D-02), with no polarity marking-MT1 and MT2 terminals are functionally identical and interchangeable for bidirectional operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar thyristor surge protection applications.

Compared with SM15T33CA and BT138-600, the MMT05A310T3 delivers purpose-built telecom surge protection with guaranteed fail-safe shorting, 50 A surge rating, and direct compliance to Telcordia/ITU/IEC standards-making it uniquely suited for secondary protection in regulated customer-premises equipment.

Availability

MMT05A310T3 is available at Aetrix Electronics and suitable for DSL line interface protection, POTS telephone line protection, and ISDN BRI line protection requiring stable component supply and long-term lifecycle support.

Supply support for MMT05A310T3 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 focused on energy-efficient electronics, with leadership in automotive, industrial, cloud power, and sensing solutions.

The MMT05A310T3 belongs to onsemi's Thyristor Surge Protector (TSPD) product line, engineered specifically for secondary overvoltage protection in telecom infrastructure-balancing high surge capability, fail-safe reliability, and regulatory compliance for customer-premises equipment.

FAQ

What is the exact breakover voltage specification for MMT05A310T3?

The MMT05A310T3 has a typical bidirectional breakover voltage (V_BO) of 365 V at 60 Hz with 1.0 A rms surge current, and a maximum of 400 V under the same conditions. This value is measured with 1000 V rms open-circuit voltage and 1.0 kΩ series resistance per the datasheet test setup. The MMT05A310T3 maintains this threshold across both polarities and exhibits a positive temperature coefficient of +0.08%/°C.

Does MMT05A310T3 meet Telcordia GR-1089 compliance?

Yes, the MMT05A310T3 is explicitly cited in the datasheet as used to help equipment meet Telcordia GR-1089, along with ITU-T K.20/K.21 and IEC 60950. Its 50 A 10×1000 µs surge rating, 2000 V/µs dv/dt immunity, and fail-safe short-circuit behavior are aligned with Category A secondary protection requirements defined in GR-1089 for customer-premises telecom equipment.

What is the package type and marking code for MMT05A310T3?

The MMT05A310T3 uses the SMA (DO-214AC) surface-mount package, Case 403D-02, with dimensions per JEDEC standard. Its marking code is "PBJ", laser-etched on the device body. The SMA package supports reflow soldering with a maximum lead temperature of 260°C for 10 seconds, and ships in 12 mm tape-and-reel format (5,000 units per reel).

How does MMT05A310T3 behave after a surge event?

The MMT05A310T3 is designed to fail short-circuit when overstressed beyond its rated surge capability-a fail-safe mechanism that prevents continued unprotected operation. Post-surge, it presents a low-resistance path (<1 Ω) between MT1 and MT2, which can be detected by system monitoring circuits. This behavior is intrinsic to its thyristor structure and is confirmed in the datasheet's "Fail-Safe, Shorts When Overstressed" feature listing.

Can MMT05A310T3 replace unidirectional TSPDs in existing designs?

No-MMT05A310T3 is strictly bidirectional and cannot substitute for unidirectional TSPDs without circuit redesign. Its symmetric MT1/MT2 terminals require placement with no polarity constraint, whereas unidirectional devices have defined anode/cathode orientation. Replacing a unidirectional part with MMT05A310T3 would require verifying that the protection topology (e.g., line-to-ground vs. line-to-line) remains valid and that the 365 V breakover voltage aligns with system withstand requirements.