Abstract: A motor driver includes an H-bridge having a first differential input, a second differential input, and a differential output; a sensing circuit coupled to the differential output of the H-bridge; a comparison and logic circuit coupled to the sensing circuit; a pair of pre-driver circuits coupled to the comparison and logic circuit for driving at least one of the differential inputs of the H-bridge; and a pair of level shifters coupled between the comparison and logic circuit and the sensing circuit. The pair of level shifters is used to assure that the VGS of a pair of serially coupled transistors in the sensing circuit do not change with temperature, motor current, or voltage, and each includes a transistor receiving a reference current. The pair of level shifters each further includes a serially coupled diode and zener diode for preventing current from flowing from the differential output of the H-bridge to the level-shifting transistor.

Abstract: A pen fault check circuit for an ink jet printer that includes a comparator that further includes a pen signal input, and a switch array coupled to the pen signal input, where the switch array includes a high voltage diode. Also, a method of checking for faults in a pen of an ink jet printer that includes the steps of generating a pen signal from a first constant current source and a pulse line resistance from a pulse line of an ink jet nozzle, generating a reference signal from a second constant current source and an external resistance from a external resistor, where the first current source and the second current source generate equal currents, and comparing the pen signal and the reference signal to determine if the ink jet nozzle is in a fault state.

Abstract: A motor driver having over current detection circuitry includes an H-bridge having a first differential input, a second differential input, and a differential output; a sensing circuit coupled to the differential output of the H-bridge; a comparison and logic circuit coupled to the sensing circuit; a pair of pre-driver circuits coupled to the comparison and logic circuit for driving at least one of the differential inputs of the H-bridge; and a pair of level shifters coupled between the comparison and logic circuit and the sensing circuit. The H-bridge includes a first side having a first transistor coupled to a second transistor, and a second side having a third transistor coupled to a fourth transistor. The first and third transistors are power PDMOS transistors, and the second and fourth transistors are power NDMOS transistors.

Abstract: A pen fault check circuit for an ink jet printer that includes a comparator that further includes a pen signal input, and a switch array coupled to the pen signal input, where the switch array includes a high voltage diode. Also, a method of checking for faults in a pen of an ink jet printer that includes the steps of generating a pen signal from a first constant current source and a pulse line resistance from a pulse line of an ink jet nozzle, generating a reference signal from a second constant current source and an external resistance from a external resistor, where the first current source and the second current source generate equal currents, and comparing the pen signal and the reference signal to determine if the ink jet nozzle is in a fault state.