STMicroelectronics SM6T250CAY

Overview

SM6T250CAY from STMicroelectronics is a bidirectional 600 W automotive-grade Transil™ TVS diode designed for surge and ESD protection in high-reliability vehicle electronics. It features a 213 V stand-off voltage, 344 V clamping voltage at 1.75 A (10/1000 µs), 175 °C maximum junction temperature, and AEC-Q101 qualification - deployed in powertrain control units, body control modules, and infotainment power rails.

For engineers reviewing the SM6T250CAY datasheet, SM6T250CAY pinout, SM6T250CAY application, or SM6T250CAY equivalent, key selection criteria include ISO 7637-2 surge immunity (up to 30 kV contact/air discharge per IEC 61000-4-2 and ISO 10605), low leakage (200 nA @ 25 °C), SMB package compatibility, and thermal stability up to 175 °C junction temperature.

Technical Context

The SM6T250CAY employs planar junction technology to achieve low leakage current and stable breakdown behavior across wide temperature ranges. Its bidirectional architecture enables symmetrical transient suppression on AC-coupled or floating signal/power lines without polarity constraints.

Clamping performance is defined by dynamic resistance (15 Ω at 8/20 µs, 11 Ω at 10/100 µs) and temperature coefficient (10⁻⁴/°C), enabling accurate V_CL prediction at elevated T_j using V_CL@T_j = V_CL@25°C × (1 + α_T × (T_j − 25)).

Key Specifications

Pinout & Package

SM6T250CAY is housed in an SMB (DO-214AA) surface-mount package per JEDEC outline, with molded plastic case, solder-plated terminals, and UL 94 V0-compliant epoxy. The device is bidirectional and has no polarity marking band.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ250A and SMCJ250CA, SM6T250CAY delivers optimal balance of bidirectional capability, SMB footprint constraint, and 600 W surge handling - making it ideal for space-constrained, polarity-agnostic automotive nodes where thermal and ESD margins are tightly specified.

Availability

SM6T250CAY is available at Aetrix Electronics and suitable for powertrain control units, body control modules, and infotainment power supplies requiring stable component supply with full AEC-Q101 traceability and automotive-grade lot control.

Supply support for SM6T250CAY 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, designing and manufacturing microcontrollers, power devices, sensors, and analog ICs for automotive, industrial, and consumer markets.

SM6T250CAY belongs to ST's Transil™ TVS diode family, engineered specifically for robust, high-temperature automotive transient protection - emphasizing low leakage, precise clamping, and compliance with ISO 7637-2, IEC 61000-4-2, and AEC-Q101.

FAQ

What is the maximum clamping voltage of SM6T250CAY under a 10/1000 µs surge?

The maximum clamping voltage is 344 V at 1.75 A for a 10/1000 µs waveform, measured at T_amb = 25 °C. This value increases linearly with junction temperature at 10⁻⁴/°C, so at 150 °C T_j, V_CL ≈ 344 V × (1 + 0.0001 × 125) = 348.3 V.

Is SM6T250CAY suitable for protecting CAN FD data lines?

No - SM6T250CAY is not optimized for high-speed data line protection due to its 300 pF typical junction capacitance at 0 V, which would distort CAN FD signaling above 2 Mbps. Use ST's ESDCAN03-2BM or similar low-capacitance (<3 pF) automotive TVS for CAN FD interfaces.

Does SM6T250CAY require heatsinking on standard FR-4 PCBs?

Heatsinking is not required for single-pulse events, but thermal performance improves significantly with ≥1 cm² of 2 oz copper connected to both terminals. Figure 8 in the datasheet shows R_thJA drops from 120 °C/W (no copper) to ~50 °C/W with 2 cm² copper, supporting repeated surge duty cycles at elevated ambient temperatures.

How does SM6T250CAY differ from SM6T250A?

SM6T250CAY is bidirectional (CAY suffix), while SM6T250A is unidirectional (A suffix). The bidirectional version clamps symmetrically for both polarities, enabling use on floating or AC-coupled lines; the unidirectional version requires correct cathode orientation and offers slightly tighter V_BR tolerance but cannot suppress negative-going transients.