Bridge circuit for driving an inductive load with a shoot-through prevention circuit

A full wave bridge circuit for driving an inductive load, of the kind including a positive voltage supply conductor, a ground conductor, first and second NPN source driver transistors respectively having collectors connected to said supply conductor, first and second NPN sink driver transistors respectively having emitters connected to said ground conductor, said first and second source driver transistors having emitters connected respectively to the collectors said first and second sink drivers, first and second output load terminals connected respectively to said first and second source driver emitters, first and second bridge-control source-input conductors to which one pair of bridge-control signals may be applied are connected directly to the bases respectively of said first and second source driver transistors;

• first and second bridge-control sink-input conductors to which another pair of bridge-control signals may be applied are connected directly to the bases respectively of said first and second sink driver transistors, a first fly-back diode connected cathode-to-anode across one of said first driver transistors collector-to-emitter, a second fly-back diode connected across the corresponding of said second driver transistors collector-to-emitter;
• wherein the improvement comprises:
• a) a first base resistor connected from base to emitter of connected from base to emitter of said corresponding second driver transistor;
• b) first and second auxiliary protective NPN transistors having collectors respectively connected to said collectors of said one first and corresponding second driver transistors, and having emitters respectively connected to said bases of said one first and corresponding second driver transistors;
• and
• c) first and second auxiliary resistors connected respectively from the bases of said first and second auxiliary transistors to respectively said first and second bridge-control input conductors that are connected respectively to said one first and corresponding second driver transistors.

A full wave bridge circuit for driving an inductive load, of the kind including a positive voltage supply conductor, a ground conductor, first and second NPN source driver transistors respectively having collectors connected to said supply conductor, first and second NPN sink driver transistors respectively having emitters connected to said ground conductor, said first and second source driver transistors having emitters connected respectively to the collectors said first and second sink drivers, first and second output load terminals connected respectively to said first and second source driver emitters, first and second bridge-control source-input conductors to which one pair of bridge-control signals may be applied are connected directly to the bases respectively of said first and second source driver transistors;

• first and second bridge-control sink-input conductors to which another pair of bridge-control signals may be applied are connected directly to the bases respectively of said first and second sink driver transistors, a first fly-back diode connected cathode-to-anode across one of said first driver transistors collector-to-emitter, a second fly-back diode connected across the corresponding of said second driver transistors collector-to-emitter;
• wherein the improvement comprises:
• a) first and second base resistors connected from the emitter to the bridge-control input conductors of said one first and corresponding second of said driver transistors, respectively;
• b) first and second auxiliary protective NPN transistors having emitters connected respectively to said first and second bridge-control input conductors, and respectively having collectors connected to said collector of said one first and second corresponding driver transistors;
• and
• c) first and second auxiliary resistors connected respectively to the bases of said first and second auxiliary transistors from said first and second bridge-control input conductors of said respective one first and corresponding second driver transistors.