Allegro MicroSystems Inc.'s complete three phase brushless DC
motor pre-driver has outputs for direct high current gate drive of an all
N-channel power MOSFET. The three phase bridge has a maximum supply voltage of
38 V. The A4938 includes Hall element inputs, a sequencer
for commutation control, fixed off time pulse width modulation (PWM) current
control and locked rotor protection. Output current is scalable with the choice
of external MOSFETS. ENABLE, DIRECTION and BRAKE inputs can be used to control
the motor, speed, position and torque. Output speed can be regulated using open
drain FG1 output that changes state at each Hall transition.
external MOSFETS can be PWM'd with the ENABLE input or with the internal PWM
current regulator. In both cases the A4938 synchronous rectification feature
will turn on the appropriate MOSFET(s) during current decay to reduce power
dissipation. The A4938 uses low cost Hall elements with noise filtering to
prevent false commutation signals. A 5V regulated supply output is provided to
power the three HALL elements. Internal circuit protection includes thermal
shutdown with hysteresis, under voltage lockout, over voltage protection with
two voltage settings, locked rotor and dead time protection. Special power up
sequencing is not required. Operating temperature range is -40 to 85C. The A4938EETTR-T is supplied in a 5 ×
5 mm 28-lead QFN package with exposed thermal pad.
A flyer or flier, also called a circular, handbill or leaflet, is a form of paper advertisement intended for wide distribution and typically posted or distributed in a public place or through the mail.
From home enthusiasts to workers on the manufacturing floor, everyone's imagination is captured by the potential of 3D printing. Prototyping, spare parts creation, art delivery, human organ creation, and even mass product production are all being targeted as current and potential uses for the technology.
ABI Research, a firm based in the UK that specializes in analyzing global connectivity and other emerging technologies, estimates there will be 40.9 billion active wirelessly interconnected “things” by 2020. The driving force is the usual suspect: the Internet of Things.
Just in time for Earth Day, chemicals leader Bayer MaterialScience reported from the UTECH Europe 2015 polyurethane show on programs and applications using its materials to help reduce energy usage. The company also gave an update on its CO2-based PU as that eco-friendly material comes closer to production.
Solar and wind energy are becoming more viable as a source of energy on the electric grid. For decades, the major drawback to solar and wind was that they’re temperamental. A cloudy day kills solar and a still day renders the wind turbines useless. Automation tools, however, are providing a path to help these renewables become practical.
In honor of Earth Day, the National Security Agency has launched the STEM Recycling Challenge in Maryland schools to encourage kids to think about where the garbage they throw out every day actually goes. The agency has also introduced “Dunk,” a muscular blue cartoon recycling bin wearing shorts and sneakers.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.