Abstract: A circuit for regulating the slope of a transistor includes the transistor and a monitor module coupled to the transistor to evaluate the slope of the transistor. The circuit further includes a comparator coupled the monitor module to compare the slope with a target slope. The circuit further includes a driver coupled to the comparator and the transistor to regulate the slope of the transistor based on output of the comparator by increasing or decreasing voltage supplied to the transistor at most once per pulse cycle until the slope reaches the target slope.

Abstract: In one embodiment, a method of forming an LED control circuit may include configuring the LED control circuit to receive a sense signal that is representative of a value of an LED current flow through a plurality of LED strings wherein each LED string includes a plurality of series coupled LEDs; configuring a detector circuit of the LED control circuit to detect the LED current being no greater than a first value and responsively initiate forming a first time period; and configuring the LED control circuit to inhibit forming the LED current responsively to termination of the first time period.

Abstract: In one embodiment, a method of forming an LED control circuit may include configuring the LED control circuit to receive a sense signal that is representative of a value of an LED current flow through a plurality of LED strings wherein each LED string includes a plurality of series coupled LEDs; configuring a detector circuit of the LED control circuit to detect the LED current being no greater than a first value and responsively initiate forming a first time period; and configuring the LED control circuit to inhibit forming the LED current responsively to termination of the first time period.

Abstract: In one embodiment a method to compensate for the sensitivity drift of a magnetic field sensor for sensing a magnetic field comprises forming a reference magnetic field having first magnetic field parameters, e.g. a first amplitude and/or direction, in a first step and second magnetic field parameters, a second amplitude and/or direction, in a second step and a bias signal is formed without adjusting the bias signal with a feedback signal derived from an output signal of the magnetic field sensor.

Abstract: A method for starting a brushless DC motor. A rotor is aligned with a stator in accordance with a predetermined phase. After alignment, the rotor is positioned in accordance with another phase, two phases are skipped, a timer is set to a first count time, and the rotor is aligned with the stator in accordance with a third phase. Then the timer is restarted and the rotor is aligned with the stator in accordance with a fourth phase. After a first delay, first back electromotive force value is stored. The timer is stopped when the first back electromotive force value substantially equals a peak amplitude of opposite polarity. The timer is updated to a second count time that is substantially equal to a time at which the second timer was stopped. The process is repeated until the rotor has a position and a velocity that are suitable for normal operation.

Abstract: The present invention provides a method to compensate for the sensitivity drift of a magnetic field sensor for sensing a magnetic field. The magnetic field sensor comprises at least four electrodes. The method comprises a first step where a first set of two electrodes is used to bias the sensor and a second set of two electrodes is used to sense an output signal of the magnetic field sensor, and a second step where the second set of two electrodes is used to bias the sensor and the first set of two electrodes is used to sense an output signal of the magnetic field sensor. The method is characterized in that at least one of the first or the second step is subdivided in at least a first sub-step and a second sub-step. A reference magnetic field has first magnetic field parameters, e.g. a first amplitude and/or direction, in the first sub-step and second magnetic field parameters, a second amplitude and/or direction, in the second sub-step.

Abstract: A method for starting a brushless DC motor. A rotor is aligned with a stator in accordance with a predetermined phase. After alignment, the rotor is positioned in accordance with another phase, two phases are skipped, a timer is set to a first count time, and the rotor is aligned with the stator in accordance with a third phase. Then the timer is restarted and the rotor is aligned with the stator in accordance with a fourth phase. After a first delay, first back electromotive force value is stored. The timer is stopped when the first back electromotive force value substantially equals a peak amplitude of opposite polarity. The timer is updated to a second count time that is substantially equal to a time at which the second timer was stopped. The process is repeated until the rotor has a position and a velocity that are suitable for normal operation.

Abstract: The invention relates to a signaling system for use in a system for monitoring and/or controlling a stack of power cells. The stack of power cells is series connected, i.e. the negative terminal of one power cell is connected to the positive electrode of the adjacent power cell. A monitoring device is associated with each power cell to monitor characteristics of the power cell (temperature, voltage). Every monitoring device is powered by the power cell it is associated. The monitoring device monitors the status of the cell (e.g. it measures the difference of potential between the positive terminal and the negative terminal of that cell but it may also measure the temperature of the power cell, the pH of the electrolyte if the power cell Ci is a battery, etc. and communicates information on the status of the cell to other monitoring devices. The monitoring devices are daisy chained.

Abstract: A differential level shifter employs a variable current mirror to maintain a reference voltage at one output while the other output follows a differential input. Resistor networks allow postproduction trimming of load resistors and the current mirror, resulting in a precise and accurate output of the differential signal. An active cascode circuit enhances current mirror balance and high frequency operation.

Abstract: A circuit for determining a direction of rotation of an electric motor, the motor having asymmetry and/or eccentricity in a profile of back electromotive force as a function of angular position of a rotor with respect to a stator, the circuit receiving a signal representing the BEMF, and use the corresponding asymmetry and/or eccentricity in the signal to derive the direction of rotation. The signal representing the back emf can be generated by a control circuit. The control circuit can have a feedback loop regulator to generate a control signal (TL or TR) to control a current drive circuit (11,12) to control an amplitude of current (iw) in the windings, the feedback loop regulator being arranged to compare the amplitude of the current (iw) in the windings with a reference value (iset), and use the control signal to provide the signal representing the back electromotive force.

Abstract: The present invention provides a method to compensate for the sensitivity drift of a magnetic field sensor for sensing a magnetic field. The magnetic field sensor comprises at least four electrodes. The method comprises a first step where a first set of two electrodes is used to bias the sensor and a second set of two electrodes is used to sense an output signal of the magnetic field sensor, and a second step where the second set of two electrodes is used to bias the sensor and the first set of two electrodes is used to sense an output signal of the magnetic field sensor. The method is characterized in that at least one of the first or the second step is subdivided in at least a first sub-step and a second sub-step. A reference magnetic field has first magnetic field parameters, e.g. a first amplitude and/or direction, in the first sub-step and second magnetic field parameters, a second amplitude and/or direction, in the second sub-step.

Abstract: A circuit for determining a direction of rotation of an electric motor, the motor having asymmetry and/or eccentricity in a profile of back electromotive force as a function of angular position of a rotor with respect to a stator, the circuit receiving a signal representing the BEMF, and use the corresponding asymmetry and/or eccentricity in the signal to derive the direction of rotation. The signal representing the back emf can be generated by a control circuit. The control circuit can have a feedback loop regulator to generate a control signal (TL or TR) to control a current drive circuit (11,12) to control an amplitude of current (iw) in the windings, the feedback loop regulator being arranged to compare the amplitude of the current (iw) in the windings with a reference value (iset), and use the control signal to provide the signal representing the back electromotive force.

Abstract: The invention relates to a signaling system for use in a system for monitoring and/or controlling a stack of power cells. The stack of power cells is series connected, i.e. the negative terminal of one power cell is connected to the positive electrode of the adjacent power cell. A monitoring device is associated with each power cell to monitor characteristics of the power cell (temperature, voltage). Every monitoring device is powered by the power cell it is associated. The monitoring device monitors the status of the cell (e.g. it measures the difference of potential between the positive terminal and the negative terminal of that cell but it may also measure the temperature of the power cell, the pH of the electrolyte if the power cell Ci is a battery, etc. and communicates information on the status of the cell to other monitoring devices. The monitoring devices are daisy chained.

Abstract: A comparator has first and second current paths, each passing from an input through a transistor, through a current source to ground, the second current path also having a reference voltage drop element coupled in series with the second input. The gates of the transistors are coupled to form a current mirror. The reference voltage drop element enables higher voltages to be input and compared to higher thresholds above an internal supply voltage level without the need for dividing resistors to reduce the input voltage. Avoiding such resistors means the power dissipation and the silicon area used can be kept lower. ESD vulnerability is reduced since the inputs are not coupled to gates of MOS transistors. Overvoltage protection across the source and gate of the second transistor can be added.

Abstract: A differential level shifter employs a variable current mirror to maintain a reference voltage at one output while the other output follows a differential input. Resistor networks allow postproduction trimming of load resistors and the current mirror, resulting in a precise and accurate output of the differential signal. An active cascode circuit enhances current mirror balance and high frequency operation.

Abstract: A comparator has first and second current paths, each passing from an input through a transistor, through a current source to ground, the second current path also having a reference voltage drop element coupled in series with the second input. The gates of the transistors are coupled to form a current mirror. The reference voltage drop element enables higher voltages to be input and compared to higher thresholds above an internal supply voltage level without the need for dividing resistors to reduce the input voltage. Avoiding such resistors means the power dissipation and the silicon area used can be kept lower. ESD vulnerability is reduced since the inputs are not coupled to gates of MOS transistors. Overvoltage protection across the source and gate of the second transistor can be added.