Microsemi Corporation

Yuji Yoshida

Chii-Fa Chiou

Xiaoping Jin

Yuji Isobe

A cold cathode fluorescent lamp controller exhibiting a multi-function terminal and operative alternately in a strike mode and a run mode, the controller comprising: a phase locked loop arranged for synchronization of an oscillator, associated with the controller, with an external signal, the phase locked loop comprising a capacitor coupled to the multi-function terminal; and a soft start circuit arranged to limit drive current immediately after reset of the controller responsive to a signal at the multi-function terminal. In one embodiment the controller further comprises an error detection circuit arranged to output an error signal on the multi-function terminal. In one embodiment the controller further comprises a frequency sweeping circuit operative to sweep the frequency of a drive signal during the strike mode of the controller, the frequency of the drive signal being swept by the frequency sweeping circuit responsive to a signal at the multi-function terminal.

CCFL controller with multi-function terminal

A compensation circuit for protecting a lamp from a large transient current. The compensation circuit may include a saw tooth generator configured to generate a saw tooth signal with an amplitude corresponding to a supply voltage of the lamp. A pulse width modulated signal may be generated by a comparator of the compensation circuit based on the saw tooth signal and a DC signal. The duty cycle of the pulse width modulated signal may be used by a controller to control the duration of time that current flows through the lamp. When the supply voltage of the lamp transitions from a low voltage to a high voltage, the amplitude of the saw tooth signal increases. When the amplitude of the saw tooth signal increases, the duty cycle of the pulse width modulated signal decreases thereby causing the controller to decrease the duration of time that current flows through the lamp.

Protecting a cold cathode fluorescent lamp from a large transient current when voltage supply transitions from a low to a high voltage

A transimpedance amplifier selectively activates DC compensation to optimize a signal-to-noise ratio for an optical receiver. The optical receiver includes a photodiode that converts a light signal to an electrical current signal, and the transimpedance amplifier converts the electrical current signal to a pair of differential voltage signals for further processing. The electrical current signal is provided to the transimpedance amplifier by connecting a cathode of the photodiode to a first input amplifier via a DC blocking capacitor and by directly connecting an anode of the photodiode to a second input amplifier. The transimpedance amplifier includes a DC correction circuit that generates a correction current when an output of the first input amplifier exceeds a predefined threshold. The correction current is added to an input of the second input amplifier to adjust a DC offset at an output of the second input amplifier.

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Irvine, CA, United States of America

Yuji Yoshida