Abstract: Techniques and apparatus for limiting the current through a motor, such as a motor for rotating a rotatable element of a hard drive. The current can be limited based on a threshold. A first threshold value can be set for a first time period. A second threshold value can be set for a second time period in which the current through the motor rises. The second threshold value is lower than the first threshold value. A spike in the supply current upon accelerating the rotatable element of the motor can thereby be reduced or eliminated.

Abstract: A stepwise voltage ramp generator includes a tank capacitor, a terminal of which is coupled to a reference potential to be charged with a voltage ramp. A transistor couples the tank capacitor to a supply line. A diode-connected transistor, biased with a bias current is coupled to the transistor to form a current mirror. A by-pass switch is electrically coupled in parallel to the diode-connected transistor, and is controlled by a PWM timing signal, the duty-cycle of which determines a mean slope of the generated voltage ramp.

Abstract: A method for determining gain of a back-electromotive force amplifier may include setting an electric motor into a tri-state function mode and storing a first quasi steady-state value for back-electromotive force from the difference signal, and forcing a reference current through the electric motor and determining a first value of the gain of the amplifier for equaling a difference signal to the first quasi steady-state value. The method may further include setting the electric motor into a tri-state function mode a second time and storing a second quasi steady-state value for back-electromotive force from the difference signal, and increasing the first value of the gain by an amount proportional to a difference between the second quasi steady-state value and the first quasi steady-state value.

Abstract: Techniques and apparatus for limiting the current through a motor, such as a motor for rotating a rotatable element of a hard drive. The current can be limited based on a threshold. A first threshold value can be set for a first time period. A second threshold value can be set for a second time period in which the current through the motor rises. The second threshold value is lower than the first threshold value. A spike in the supply current upon accelerating the rotatable element of the motor can thereby be reduced or eliminated.

Abstract: A method for determining gain of a back-electromotive force amplifier may include setting an electric motor into a tri-state function mode and storing a first quasi steady-state value for back-electromotive force from the difference signal, and forcing a reference current through the electric motor and determining a first value of the gain of the amplifier for equaling a difference signal to the first quasi steady-state value. The method may further include setting the electric motor into a tri-state function mode a second time and storing a second quasi steady-state value for back-electromotive force from the difference signal, and increasing the first value of the gain by an amount proportional to a difference between the second quasi steady-state value and the first quasi steady-state value.

Abstract: A stepwise voltage ramp generator includes a tank capacitor, a terminal of which is coupled to a reference potential to be charged with a voltage ramp. A transistor couples the tank capacitor to a supply line. A diode-connected transistor, biased with a bias current is coupled to the transistor to form a current mirror. A by-pass switch is electrically coupled in parallel to the diode-connected transistor, and is controlled by a PWM timing signal, the duty-cycle of which determines a mean slope of the generated voltage ramp.

Abstract: The method controls a charge pump generator having at least an output tank capacitor on which a regulated output voltage of the generator is produced, and a pump capacitor that is connected to a supply node and to ground during charge phases and is coupled in an anti-parallel configuration to the output tank capacitor during charge transfer phases, alternated to the charge phases. The method limits the current absorbed from the supply because the transfer capacitor is charged during at least an initial charge phase with a constant charge current of a pre-established value.

Abstract: The electric charge transferred in a charge transfer phase from the pump capacitor to the tank capacitor is diminished by reducing the amplitude of the voltage swing on the transfer capacitor proportionally to the current to be supplied. This is done by limiting the maximum voltage on the pump capacitor to a certain value. This maximum value is calculated to make the voltage on the transfer capacitor reach a certain minimum voltage at the end of the charge transfer phase. A charge pump generator includes a driving circuit that isolates the pump capacitor when the voltage on it reaches the maximum value.

Abstract: The electric charge transferred in a charge transfer phase from the pump capacitor to the tank capacitor is diminished by reducing the amplitude of the voltage swing on the transfer capacitor proportionally to the current to be supplied. This is done by limiting the maximum voltage on the pump capacitor to a certain value. This maximum value is calculated to make the voltage on the transfer capacitor reach a certain minimum voltage at the end of the charge transfer phase. A charge pump generator includes a driving circuit that isolates the pump capacitor when the voltage on it reaches the maximum value.

Abstract: The method controls a charge pump generator having at least an output tank capacitor on which a regulated output voltage of the generator is produced, and a pump capacitor that is connected to a supply node and to ground during charge phases and is coupled in an anti-parallel configuration to the output tank capacitor during charge transfer phases, alternated to the charge phases. The method limits the current absorbed from the supply because the transfer capacitor is charged during at least an initial charge phase with a constant charge current of a pre-established value.