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.
What makes this movie stand out from the typical high school sports story is that the teenagers are undocumented immigrants, and the big game is a NASA-sponsored marine robotics competition. Like many other Hollywood movies, however, Spare Parts only tells part of the story. What the film shows -- and doesn’t show -- raises important issues affecting STEM education in the US.
Instead of sifting through huge amounts of technical data looking for answers to assembly problems, engineers can now benefit from 3M's new initiative -- 3M Assembly Solutions. The company has organized its wealth of adhesive and tape solutions into six typical application areas, making it easier to find the best products to solve their real-world assembly and bonding problems.
Load dump occurs when a discharged battery is disconnected while the alternator is generating current and other loads remain on the alternator circuit. If left alone, the electrical spikes and transients will be transmitted along the power line, leading to malfunctions in individual electronics/sensors or permanent damage to the vehicle’s electronic system. Bottom line: An uncontrolled load dump threatens the overall safety and reliability of the vehicle.
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.