Abstract: A power-limit protection circuit with an efuse element. The power-limit protection circuit has an efuse element coupled between a first terminal and a second terminal. The power-limit protection circuit judges whether a calculated power signal defined from a current signal flowing through the efuse element and a voltage signal at a terminal of the efuse element is larger than a predetermined power threshold. When the calculated power signal is larger than the predetermined power threshold, the power-limit protection circuit increases an impedance of the efuse element to limit the current signal between the first terminal and the second terminal such that the power delivered through the efuse element is limited within the predetermined power threshold.

Abstract: Three example inverter designs are described that can be tailored to drive from one to dozens of lamps of a backlight for a liquid crystal display. For each design the lamps are driven by a 40 kHz to 60 kHz sine wave. The lamp voltage is ˜1200V to “strike” the lamps and ˜600V to produce the optimal 5 mA in each lamp. The designs are: a Royer linear oscillator driven by a buck converter stage, a push-pull inverter that drives the high voltage transformer directly, and a class-D amplifier that produces the drive sine wave using a pulse width modulation technique.

Abstract: Various systems and methods for LCD backlight control are disclosed herein. For example, some embodiments of the present invention provide an LCD backlight circuit with an analog inverter circuit that provides a drive voltage to a lamp. A current traversing the lamp is sensed and provided to a digital control circuit. Based on the sensed current, the digital control circuit generates a control signal that is fed back to the analog inverter circuit. In some cases, the digital control circuit is used to cause a gradual increase in voltage applied to the lamp to achieve ignition of the lamp. In other cases, the digital control is used to provide a pre-distorted sine wave that attenuates one or more harmonics introduced into the system by the non-linearities of the lamp.

Abstract: A PFC circuit modulating a power line using pulse width modulation (PWM) to drive a power MOSFET and series inductor across the power line. Since many modern electronic systems include a power factor correction circuit (PFC) that already includes a series inductor and power MOSFET, a PLC is incorporated into a controller to inject a PLC transmit signal into a control loop for the PFC circuit. This can be done using either an analog PFC controller, such as the UCC28517, the UCC2819A, or a digital PFC controller such as based on a TMS32OC24xx DSP.

Abstract: A method that allows a digital communications system to detect the presence of transmitted messages in noisy environments. The system includes an OFDM transmitter and an OFDM receiver. The OFDM transmitter converts a digital signal to be transmitted to a plurality of sub-signals, each corresponding to a respective sub-carrier frequency. The signal is a packet including a preamble field having a known data pattern. The transmitter pre-codes the preamble data pattern, maps the data to corresponding phase information, converts the sub-signals to the time domain, and converts the sub-signals to analog form for subsequent transmission. The OFDM receiver receives the transmitted sub-signals, converts the sub-signals to digital form, converts the sub-signals to the frequency domain, and subjects the sub-signals to preamble detection processing to detect the signals' presence.

Abstract: A resonant scanning mirror driver configured to drive a micro-electro-mechanical system (MEMS) mirror to a desired deflection utilizes a PWM pattern selected from patterns having a preset number of bits. The patterns reflect the first positive quarters of the PWM pattern and the remaining quarters are generated utilizing the symmetry of the sine wave that is generated. Patterns having a harmonic distortion less than a preselected maximum are sorted into amplitude bins and ranked to generate a subset of patterns having a linearly varying deflection amplitude.

Abstract: A resonant scanning mirror driver configured to drive a micro-electro-mechanical system (MEMS) mirror to a desired deflection utilizes a PWM pattern selected from patterns having 32, 40, 48, 56 or 64 bits. The patterns reflect the first positive and negative quarters of the PWM pattern and the remaining quarters are generated utilizing the symmetry of the sine wave that is generated.

Abstract: A method of deriving optimum read channel parameters for use in reading servo sector data from a disk drive having a head mounted on an actuator, a read channel including a preamplifier, a disk having a plurality of tracks, each track having multiple sequentially active servo sectors, a sampled signal head positioning servo controller to control the actuator position, a microprocessor, and a memory. The first step is to store default values and variable test values associated with read channel parameters. The microprocessor is programmed to detect certain servo errors which may occur. The read channel parameters are initially set to the default values in order to ensure that the disk drive can properly perform a seek. A series of seeks is then performed in alternating directions over a band of tracks.

Abstract: In a disk drive having a disk and a sampled track positioning servo system with a plurality of servo tracks spaced apart by a servo track pitch, a method and apparatus for separately determining the pitch of data tracks based on the servo track pitch and address fields located on the servo tracks. By separately optimizing data track pitch and servo track pitch, the design requirements for data density and servo control can be satisfied without the conflict imposed by a fixed relationship of the two track pitch dimensions.