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AssigneeAllegro MicroSystems, LLC
InventorsAlberto Bilotti, Jose L. Tallarico
Estimating the term…
A full-wave bridge driver has four driver transistors. A motor is connected to the output terminals of the bridge. A fault detector latches off the four driver transistors when the bridge current jumps essentially instantaneously to exceed a predetermined safe-peak value due to a fault occurring in the bridge. A comparator has a predetermined current threshold, that is less than the predetermined safe-peak value of the fault detector, and is connected to a bridge-current sensing resistor for, when the bridge current exceeds the current threshold, producing a signal proportional to the difference between the bridge current and the current threshold. A pulse-width-modulator is connected to the comparator means output, and during periods such as at motor starting when the bridge current gradually exceeds the comparator threshold value, chops the signal at the bases of the four driver transistors, varying the chopped pulse widths to hold the motor current at essentially the threshold current value. For faults that occur across the motor or between the motor and either of the DC-supply terminals, the fault current paths in the bridge do not flow through the inductance of the motor and produce a sharp rising bridge fault current that is essentially transparent to the pulse width modulator which clamps high motor start currents at a level below that at which the fault detector trips the latch and shuts off the driver transistors.
A full-wave bridge driver of the kind having two DC-supply-voltage terminals, four driver transistors connected in a circuit configured as a transistor bridge having two motor load terminals to which a motor may be connected, said bridge being connected between said two DC-supply-voltage terminals, and a fault detector means connected to said bridge for latching off said four driver transistors when the bridge current drawn by said bridge from said DC-supply terminals jumps essentially instantaneously to exceed a predetermined safe-peak value due to a fault occurring in said bridge;
A full-wave bridge driver of the kind having two DC-supply-voltage terminals, four driver transistors connected in an H-bridge configured circuit that is connected between said two DC-supply-voltage terminals, a pair of motor terminals to which a motor may be connected located respectively at the junctions between each of the two of said driver transistors forming the two series branches of said bridge circuit, and a fault detector means connected to said bridge circuit for latching off said four driver transistors when the bridge-circuit current drawn from said DC-supply terminals jumps essentially instantaneously to exceed a predetermined safe-peak value;
Dependencies are inferred from the claim text.