Abstract:
Aspects of the disclosure provide a circuit. The circuit includes a transistor configured to control energy entering the circuit from a power supply, a capacitor coupled with the transistor to store the energy that enters the circuit, and a protection circuit configured to counteract a voltage change of the transistor that is caused by a step voltage change in the power supply. In an embodiment, the protection circuit operates independent of the stored energy on the capacitor.
Abstract:
Aspects of the disclosure provide a circuit. The circuit includes a depletion mode transistor coupled to a power supply and a current path coupled with the depletion mode transistor in series to provide a current to charge a capacitor. The current path has a first resistance during a first stage, such as when the circuit initially receives power, and has a second resistance during a second stage when the capacitor is charged to have a predetermined voltage level.
Abstract:
Aspects of the disclosure provide a circuit. The circuit includes a control circuit and a return path circuit. The control circuit is configured to operate in response to a first conduction angle of a dimmer coupled to the circuit. The first conduction angle is adjusted to control an output power to a first device. The dimmer has a second conduction angle that is independent of the control of the output power to the first device. The return path circuit is configured to provide a return path to enable providing power to a second device in response to the second conduction angle.
Abstract:
An integrated circuit (IC) including a well region of the IC having a first doping level and a plurality of semiconductor regions implanted in the well region. Each of the plurality of semiconductor regions has a second doping level. The second doping level is greater than the first doping level. A plurality of polysilicon regions are arranged on the plurality of semiconductor regions. The polysilicon regions are respectively connected to the semiconductor regions. The plurality of semiconductor regions is a drain of a metal-oxide semiconductor field-effect transistor (MOSFET).
Abstract:
Analog control of the pulse width used to control the speed of a voice coil motor may be implemented using a “constant-current-charging-capacitor” configuration where the time needed to charge the capacitor is directly related to how far the actual motor speed is from the target speed. The BEMF voltage, indicative of motor speed, is sampled, and then stored in a storage capacitor, which is allowed to charge/discharge to a target voltage level. The time required to charge/discharge the capacitor to the target voltage is directly proportional to the difference between the BEMF voltage and the target voltage, and may be used directly as the pulse width (i.e., the charging time) in the PWM velocity control system. To avoid larger capacitors, a pulse multiplier circuit can be added, allowing charging/discharging the sampled voltage to the target voltage to be repeated by a number, N, of times.
Abstract:
The power required by a voice coil motor (VCM) to maintain the head in the data region of a disk drive during an idle mode is further reduced. The current supplied to the VCM is switched on and off. This takes advantage of the inherent inductance in the VCM, which maintains a current after the current supply is switched off. The current will slowly decay, with it being switched on again before it reaches a level where the average value won't offset the flex bias. In one embodiment, the current is maintained in a single direction, to offset the flex bias which pushes in one direction. Digital switches are used to reduce the power consumption of the control circuitry.
Abstract:
In a method for measuring motor speed and position by detecting the back-EMF generated during pole-pair interactions, fluctuations of a three-phase motor power supply that may affect back-EMF detection are reduced. One phase of the power supply is tristated for a certain interval preceding and during back-EMF detection. For a shorter interval during back-EMF detection, the voltage drop across the motor is reduced from the full power supply voltage. This preferably is accomplished either by pulling a first of the other two power supply phases low, while pulling a second of the other two power supply phases up to a regulated voltage below the power supply voltage, or by pulling the second of the other two phases up to the power supply voltage and pulling the first of the other two phases down to a regulated voltage above ground.
Abstract:
A circuit system and process utilizes back electromotive force (BEMF) voltage to assist in safe power down of devices, such as the read/write head in from low factor disk drives or similar devices. The BEMF voltage from a motor device, such as a spindle motor utilized in a circuit using negative voltage to drive some switches, such as positive channel metal oxide semiconductor (“PMOS”) driver transistors, to reduce and/or effectively minimize the on-resistance of the switches while delivering the current from BEMF voltage of the motor to another device, such as a motor that retracts controls a read/write head.
Abstract:
Circuits and methods are provided for producing a rail-to-rail output voltage. A circuit includes a level shifter, a source follower, and a current compensation circuit. The level shifter receives an input signal and applies a compensation voltage to the input signal relative to a voltage level of the input signal in steady-state. The source follower produces an output signal and, responsive to variations in the voltage level of the input signal, changes the voltage level of the output signal using a biasing current. The current compensation circuit, responsive to a difference between the voltage levels of the input and output signals, varies an amount of the biasing current.
Abstract:
A protection circuit for a capacitor comprises a voltage pump that selectively charges the capacitor. A current source selectively charges the capacitor. A controller selectively activates the current source while deactivating the voltage pump when a charging voltage is less than a threshold charging voltage level and selectively deactivates the current source while activating the voltage pump when the charging voltage is greater than the threshold charging voltage level.