The devices simplify automotive solenoid control circuits by saving space, reducing component count and improving reliability
MOSFET-based power schemes for solenoid and actuator control in automotive powertrains are typically built around boost, free-wheel diode or active clamp topologies. Another option is a repetitive avalanche design that dissipates energy from the inductive load by making use of the MOSFET’s ability to repeatedly handle current from the inductive load during switch off.
Offering comparable efficiencies to active clamp alternatives, such designs eliminate the need for diodes and other devices to minimise component count and circuit complexity. They also support faster switch-off times, a factor that can extend the reliability of electromechanical components such as solenoids and relays. Until now this had been a possible solution using outdated planar technology.
Now the new Repetitive Avalanche Application Specific FET (ASFET) family focused on powertrain applications can be used for controlling automotive inductive loads such as solenoids and actuators. Additionally, they provide a faster turn-off time (up to 4X) and guarantee repetitive avalanche functionality (up to one billion cycles), designs can be simplified through a reduced BOM count.
The ASFET family of products provides up to 30 per cent component footprint efficiency by reducing up to 15 board components.
Fully automotive qualified to AEC-Q101 at 175 degrees Celsius, the new MOSFETs are available in 40 V and 60 V options with typical RDS(ON) ratings from 12.5 mΩ to 55 mΩ. All of the devices are supplied in a space-saving LFPAK56D (Dual Power-SO8) copper-clip package technology, which features gull wing leads for increased board reliability and improved manufacturability including automated optical inspection (AOI).
“Typically, engineers looking to implement repetitive avalanche topologies have had to rely on devices that use older, planar semiconductor technologies. Offering automotive-qualified devices with guaranteed repetitive avalanche capabilities that are based on higher performance silicon structures will increase the number of powertrain designs that can take advantage of repetitive avalanche functionality,” explained Richard Ogden, product manager at Nexperia.
In response to industry demands to maximise performance, Nexperia has launched the Application Specific FET (ASFET) family. Other available ASFET families by the company address hot-swap, Power over Ethernet (PoE), battery protection and motor control applications.
