STMicroelectronics SM6T33CAY

Overview

SM6T33CAY from STMicroelectronics is a bidirectional automotive-grade transient voltage suppression (TVS) diode in SMB package, designed for ISO 7637-2 pulse protection (Pulse 1: −150 V; Pulse 2a: +112 V; Pulse 3a: −220 V; Pulse 3b: +150 V) and ESD robustness per ISO 10605 (±30 kV air/contact discharge). It features a 33 V standoff voltage (VRM), 45.7 V clamping voltage at 13.1 A (10/1000 µs), 600 W peak pulse power, and operates up to 150 °C junction temperature.

For engineers reviewing the SM6T33CAY datasheet, SM6T33CAY pinout, SM6T33CAY application, or SM6T33CAY equivalent, this device is selected for high-reliability automotive power line and signal line surge protection where low leakage (<0.2 µA at 25 °C), stable clamping under thermal stress, and AEC-Q101 qualification are mandatory.

Technical Context

The SM6T33CAY employs planar silicon technology to achieve low leakage current and high thermal stability across −55 °C to +150 °C operating junction range. Its bidirectional structure enables symmetrical clamping for both positive and negative transients without polarity dependency.

It delivers 600 W (10/1000 µs) and 4 kW (8/20 µs) peak pulse power with dynamic resistance of 0.84 Ω at 25 °C, enabling effective voltage limiting during fast-rising surges such as ISO 7637-2 Pulse 3b (+150 V) and ESD events exceeding IEC 61000-4-2 Level 4.

Key Specifications

Pinout & Package

SM6T33CAY is housed in an SMB (DO-214AA) surface-mount package with two terminals: Cathode and Anode. The bidirectional configuration means both terminals function symmetrically - no polarity marking required for installation. Package dimensions: 3.95 mm × 5.60 mm × 2.45 mm (L × W × H), with matte tin-plated leads compliant to J-STD-002 and MIL-STD-750 Method 2026.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ33CA and 1.5KE33CA, SM6T33CAY uniquely balances AEC-Q101 compliance, SMB footprint, 600 W surge capability, and sub-46 V clamping - making it the optimal choice for space-constrained, thermally demanding automotive electronics.

Availability

SM6T33CAY is available at Aetrix Electronics and suitable for automotive ECU design, LIN bus interface development, camera module power protection, and passive entry RF antenna feedline hardening requiring stable component supply across production lifecycles.

Supply support for SM6T33CAY 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 over 40 years of analog and protection device expertise.

The SM6TY series was developed specifically for automotive transient protection, targeting ISO 7637-2 and ISO 10605 compliance in engine control, body electronics, and ADAS subsystems - emphasizing thermal stability and AEC-Q101 reliability.

FAQ

Is SM6T33CAY unidirectional or bidirectional?

SM6T33CAY is a bidirectional TVS diode, as indicated by the "CAY" suffix in its ordering code. Its symmetrical breakdown behavior allows it to clamp both positive and negative transients equally - ideal for protecting AC-coupled or floating signal lines like LIN bus or antenna feeds without polarity concerns.

What is the maximum clamping voltage at 10 A (10/1000 µs)?

Per Table 2 of DS6905 Rev 11, SM6T33CAY has a maximum clamping voltage (VCL) of 45.7 V at 13.1 A (10/1000 µs). At 10 A, interpolation yields approximately 43.2 V - confirmed by Figure 5's VCL vs. IPP curve, ensuring protected circuits remain within safe operating area for 3.3 V or 5 V ICs.

Does SM6T33CAY require orientation-specific PCB layout?

No. Due to its bidirectional construction, SM6T33CAY has no anode/cathode functional distinction during surge events. The SMB package uses identical metallization on both terminals, and the marking "MTY" (per Table 6) does not indicate polarity - enabling rotation-insensitive placement and simplified automated assembly.

How does SM6T33CAY perform at elevated junction temperatures?

At 150 °C junction temperature, SM6T33CAY maintains 515 W peak pulse power (10/1000 µs), per Figure 3. Its temperature coefficient αT = 9.8 × 10⁻⁴ /°C adjusts clamping voltage upward linearly: VCL(150 °C) ≈ 45.7 V × [1 + 0.00098 × (150 − 25)] = ~49.9 V - still within safe margins for 5 V tolerant interfaces.