STMicroelectronics SMA6F33A

Overview

SMA6F33A from STMicroelectronics is a unidirectional 600 W transient voltage suppression (TVS) diode designed for robust ESD and surge protection in power rails and signal lines. It features a 33 V stand-off voltage (VRM), 53.3 V clamping voltage at 11.8 A (10/1000 µs), and operates up to 175 °C junction temperature - deployed in automotive body control modules, industrial PLC I/O protection, and telecom power supply inputs.

For engineers reviewing the SMA6F33A datasheet, SMA6F33A pinout, SMA6F33A application, or SMA6F33A equivalent, key selection criteria include clamping performance under 10/1000 µs surges, low leakage (<0.2 µA @ 25 °C), high-temperature reliability, and compliance with IEC 61000-4-2 Level 4 (±25 kV contact / ±30 kV air discharge).

Technical Context

The SMA6F33A employs planar silicon avalanche technology to deliver precise breakdown at 36.7–40.5 V (VBR min/max @ 1 mA), with dynamic resistance of 1.08 Ω enabling tight clamping during fast transients. Its unidirectional configuration supports DC-biased protection paths without reverse conduction.

Thermal design is enabled by a 175 °C max junction rating and validated thermal impedance curves showing <100 °C/W junction-to-ambient for single pulses on FR4 PCBs with recommended copper area. The device meets J-STD-020 MSL Level 1 and UL94 V0 flammability requirements.

Key Specifications

Pinout & Package

The SMA6F33A is housed in an industry-standard SMA (DO-214AC) flat package with matte tin-plated leads, compatible with IPC7531 footprints and JEDEC registered outline. Dimensions: 4.6 mm × 2.9 mm × 2.3 mm (L × W × H), weight 39 mg.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar transient voltage suppression applications.

Compared with SMAJ33A and SMBJ33A, the SMA6F33A uniquely balances 600 W surge capability, ultra-low leakage, and 175 °C operation in the compact SMA footprint - making it optimal for space- and temperature-critical automotive and industrial edge nodes where both size and reliability are non-negotiable.

Availability

SMA6F33A is available at Aetrix Electronics and suitable for automotive body electronics, industrial programmable logic controllers, and telecom power supply designs requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for SMA6F33A 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 devices, sensors, and protection components for automotive, industrial, and consumer markets.

The SMA6F series belongs to ST's Transil™ TVS portfolio, engineered specifically for high-reliability transient suppression in harsh environments - emphasizing low leakage, high-temperature stability, and IEC/UL-certified surge robustness.

FAQ

What is the maximum clamping voltage of SMA6F33A under a 10/1000 µs surge?

The SMA6F33A clamps to 53.3 V at 11.8 A under a 10/1000 µs waveform, as specified in Table 2 of DS12564 Rev 3. This value is measured at 25 °C ambient and represents the peak voltage imposed on the protected circuit during standardized surge testing.

Does SMA6F33A support bidirectional transient protection?

No - SMA6F33A is a unidirectional TVS diode, intended for DC-biased applications where reverse conduction is not required. Its cathode-anode polarity must be oriented with cathode toward the protected line and anode to ground. For AC or bipolar signal lines, a bidirectional variant like SMA6F33CA would be required.

Can SMA6F33A be used in reflow soldering processes?

Yes - the device is qualified for lead-free reflow per J-STD-020 MSL Level 1, with a peak profile of 240–245 °C for ≤60 seconds. Figure 20 in DS12564 specifies a ramp rate of ≤3 °C/s and controlled cooling to prevent thermal shock or delamination.

How does leakage current change with temperature for SMA6F33A?

At VRM = 33 V, leakage is 0.2 µA maximum at 25 °C and rises to 1 µA maximum at 85 °C, as confirmed in Table 2. Figure 8 shows IR increases exponentially beyond 100 °C, reaching ~1000 nA at 175 °C - still within acceptable limits for most high-temperature protection schemes.