STMicroelectronics SM15T68CAY

Overview

SM15T68CAY from STMicroelectronics is a bidirectional automotive-grade transient voltage suppression (TVS) diode in SMC package, designed for ISO 7637-2 pulse protection (Pulse1: −150 V; Pulse2a: +112 V; Pulse3a: −220 V; Pulse3b: +150 V) and ESD robustness per ISO 10605 (±30 kV air/contact). It features 68 V breakdown voltage (V_BR = 64.6–71.4 V), 92 V clamping voltage (V_CL) at 16.3 A (10/1000 µs), and 1500 W peak pulse power rating at T_amb = 25 °C.

For engineers reviewing the SM15T68CAY datasheet, SM15T68CAY pinout, SM15T68CAY application, or SM15T68CAY equivalent, key selection criteria include bidirectional surge clamping capability, AEC-Q101 qualification, low leakage (<1 µA at 85 °C), high junction temperature operation (T_j up to 150 °C), and compliance with ISO 7637-2 and ISO 10605 Level 4.

Technical Context

This bidirectional TVS diode uses planar silicon technology to achieve stable V_BR temperature coefficient (α_T = 10.4 × 10⁻⁴/°C) and low dynamic resistance (R_D = 1.26 Ω at 10/1000 µs). Its symmetrical I-V characteristics enable equal clamping in both polarities, critical for protecting differential bus lines like CAN FD or LIN against reverse-polarity transients and coupled surges.

The device operates across −55 °C to +150 °C junction temperature range and maintains ≤1 µA leakage at 85 °C under 58.1 V stand-off (V_RM). Its SMC package supports high thermal dissipation on standard FR4 PCBs, with R_th(j-a) dropping to ~80 °C/W with 3 cm² copper area per lead - enabling sustained reliability in under-hood automotive modules.

Key Specifications

Pinout & Package

SM15T68CAY is housed in an SMC (DO-214AB) surface-mount package with two terminals: Cathode (K) and Anode (A), arranged symmetrically for bidirectional operation. The matte tin-plated leads comply with J-STD-002 and MIL-STD-750 Method 2026, supporting reflow soldering per JEDEC J-STD-020 MSL Level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ68CA and TPSMD68CA, SM15T68CAY uniquely combines AEC-Q101 qualification, full ISO 7637-2 Pulse 1/2a/3a/3b validation, and 1500 W surge capacity in a thermally robust SMC package - making it the only choice for front-end protection in ASIL-B and ASIL-C automotive subsystems.

Availability

SM15T68CAY is available at Aetrix Electronics and suitable for automotive powertrain control, ADAS camera interfaces, body electronics modules, and infotainment head units requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for SM15T68CAY 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, specializing in automotive, industrial, and power management solutions with vertical manufacturing capabilities and broad automotive qualification coverage.

The SM15Txx series targets high-reliability automotive transient protection, specifically engineered to meet stringent ISO 7637-2 and ISO 10605 requirements for next-generation E/E architectures including zonal controllers and domain ECUs.

FAQ

What is the maximum clamping voltage of SM15T68CAY under a 10/1000 µs surge?

The maximum clamping voltage (V_CL) is 92 V at 16.3 A for a 10/1000 µs waveform, measured at T_amb = 25 °C. At elevated junction temperatures (e.g., 125 °C), V_CL increases by 10.4 × 10⁻⁴/°C × ΔT, reaching approximately 96.5 V - still within safe margins for 72 V-rated downstream components.

Is SM15T68CAY unidirectional or bidirectional, and how is polarity identified?

SM15T68CAY is a bidirectional TVS diode, meaning it clamps equally in both polarities. It has no polarity marking - the SMC package contains two identical terminals (Anode and Cathode), and either can serve as input or return. This eliminates orientation constraints during PCB layout and simplifies protection of differential buses.

Does SM15T68CAY meet AEC-Q101 requirements for temperature cycling and mechanical shock?

Yes - SM15T68CAY is fully AEC-Q101 qualified, having passed all required stress tests including temperature cycling (−40 °C to +125 °C, 1000 cycles), mechanical shock (3000 g), and board flex. Its planar construction and matte tin plating ensure long-term interconnect reliability in vibration-prone automotive environments.

Can SM15T68CAY be used to protect a 48 V mild-hybrid system?

No - SM15T68CAY's 68 V breakdown voltage and 92 V clamping level are optimized for 12 V automotive systems. For 48 V architectures, ST recommends SM20T78CA (78 V V_BR) or SM20T100CA (100 V V_BR), which provide appropriate standoff and clamping margins above nominal bus voltage while maintaining AEC-Q101 and ISO 7637-2 compliance.