Surge protection prevents unwanted voltage pulses in the vehicle wiring from damaging sensitive subsystems such as safety systems, control modules and infotainment equipment. Pulses can be caused by events such as electrostatic discharges (ESD) from occupants, turn-on/off of subsystems such as motor drives or climate control, or load dumps when a significant load such as the battery is suddenly disconnected. Historically, designers have chosen from devices certified to industrial standards that specify pulse shapes unrepresentative of those expected in road vehicles.
ST's SM4TY-SM30TY series of Transil miniature surge-protection devices are certified to pulse specifications used by the automotive industry. They are also qualified to the AEC-Q101 automotive reliability test standard for discrete semiconductors, and have a full Automotive-Grade Approval Certificate (AGAC). This saves designers researching for equivalence between industrial and automotive standards, and then re-certifying each new subsystem design independently. Hence new innovations are able to reach the market quickly and cost efficiently.
The Transil protection devices are housed in miniature surface-mount power packages occupying from 12.8mm2 to 46mm2 of pc-board space, capable of handling from 400W to 3000W of power contained in pulses and ESD transients present on the vehicle wiring.
Major features of ST's automotive Transil protection devices:
- Tested and certified using ISO 7637 specifications for electrical transients
- Tested and certified using ISO 10605 specifications for ESD strike
- AEC-Q101 certified
- All devices available in unidirectional or bidirectional configuration:
- SM4TY: SMA package, 2.55 x 5.05 mm, 400 W
- SMA6TY: SMA package, 2.55 x 5.05 mm, 600 W
- SM6TY: SMB package, 3.60 x 5.35 mm, 600 W
- SM15TY: SMC package, 5.90 x 7.95 mm, 1500 W
- SM30TY: SMC package, 5.90 x 7.95 mm, 3000 W
ST automotive-(AGAC) Transil protection devices are in mass production now, in SMA, SMB or SMC surface-mount packages, at prices ranging from $0.118 to $0.528 for unidirectional devices or $0.129 to $0.558 for bidirectional devices. Alternative pricing options for large quantities may be available on request.