STMicroelectronics SM4T28CAY, Automotive Grade Zener TVS Diode, Bidirectional, 400W Peak Pulse Power, 24V Reverse Standoff, 26.7V Breakdown Min, 50V Clamping, DO-214AC (SMA), AEC-Q101 Qualified.
| Parameter | Value |
|---|---|
| Type | Zener |
| Series | * |
| Mounting | Surface Mount |
| Voltage - breakdown | 26.7V |
| Voltage - clamping (Max) @ ipp | 50V |
| Voltage - reverse standoff | 24V |
| Current - peak pulse (10/1000μs) | 46A (8/20µs) |
| Power - peak pulse | 400W |
| Power line protection | No |
| Operating temperature | -55°C ~ 150°C (TJ) |
| Grade | Automotive |
| Package | Tape & Reel (TR) Cut Tape (CT) |
| Qualification | AEC-Q101 |
| Case | DO-214AC, SMA |
| Bidirectional channels | 1 |
Its 24V reverse standoff voltage matches a nominal 24V supply rail, with a minimum breakdown of 26.7V and a maximum clamping voltage of 50V at the peak pulse current of 46A (8/20µs). The 400W rating means this part can absorb substantial transient energy without failing — relevant for load-dump and inductive-switch-off events in automotive and industrial 24V systems.
Yes, the SM4T28CAY is AEC-Q101 qualified, which is the automotive-grade stress-test standard for discrete semiconductors. This qualification covers the part for use in automotive ECUs, sensors, and power distribution modules.
The SM4T28CAY is the bidirectional variant of the SM4T28A unidirectional part. Both share the same breakdown and clamping voltages, but the CA version clamps both polarities, while the A version protects only one. If the circuit already has a bridge rectifier or the line is DC-only, the unidirectional SM4T28A may be sufficient; for AC or floating lines, the bidirectional SM4T28CAY is the correct choice. The package (SMA) and footprint are identical.