Abstract: A switch for switching video signals in a set top box between a first interface for connecting the set top box to a television, a second interface for connecting the set top box to a video playback device, and decoding circuitry for decoding a video stream, the set top box including a processor having a low power mode in which the decoding circuitry is inactive, the switch including detection circuitry arranged to detect, while the processor is in the low power mode, activity on a video input line of one of the first and second interfaces, and arranged to output an activation signal to switching circuitry in the switch to activate a loop through between the first and second interfaces when activity is detected.

Abstract: An electronic system providing a video signal to an output terminal intended to be connected to a receiver having one input impedance out of two input impedances, the electronic system including an adaptable amplifier providing the video signal and capable of operating according to one operation configuration out of two operation configurations, each operation configuration being adapted to one of the two input impedances of the receiver; circuitry for detecting characteristic portions of the video signal; and control and measurement circuitry capable of measuring a signal representative of the current provided to the output terminal by the electronic system during each detected characteristic portion, and of having the adaptable amplifier adopt one of the two operation configurations based on the comparison of the representative measured signal with thresholds.

Abstract: A switch for switching video signals in a set top box between a first interface for connecting the set top box to a television, a second interface for connecting the set top box to a video playback device, and decoding circuitry for decoding a video stream, the set top box including a processor having a low power mode in which the decoding circuitry is inactive, the switch including detection circuitry arranged to detect, while the processor is in the low power mode, activity on a video input line of one of the first and second interfaces, and arranged to output an activation signal to switching circuitry in the switch to activate a loop through between the first and second interfaces when activity is detected.

Abstract: A method for providing a horizontal scan control signal for a TV set from a horizontal synchronization signal contained in a composite video signal, the horizontal synchronization signal containing horizontal synchronization pulses and parasitic pulses, the scan control signal being provided from an oscillating signal generated by an oscillator of a phase-locked loop receiving the horizontal synchronization signal, the oscillating signal having a frequency depending on a driving signal provided from the comparison between the horizontal synchronization signal and a binary phase signal, in which, at each parasitic pulse among successive parasitic pulses between two synchronization pulses, the driving signal is successively varied in the increasing direction or in the decreasing direction.

Abstract: An electronic system providing a video signal to an output terminal intended to be connected to a receiver having one input impedance out of two input impedances, the electronic system including an adaptable amplifier providing the video signal and capable of operating according to one operation configuration out of two operation configurations, each operation configuration being adapted to one of the two input impedances of the receiver; circuitry for detecting characteristic portions of the video signal; and control and measurement circuitry capable of measuring a signal representative of the current provided to the output terminal by the electronic system during each detected characteristic portion, and of having the adaptable amplifier adopt one of the two operation configurations based on the comparison of the representative measured signal with thresholds.

Abstract: A method for providing a horizontal scan control signal for a TV set from a horizontal synchronization signal contained in a composite video signal, the horizontal synchronization signal containing horizontal synchronization pulses and parasitic pulses, the scan control signal being provided from an oscillating signal generated by an oscillator of a phase-locked loop receiving the horizontal synchronization signal, the oscillating signal having a frequency depending on a driving signal provided from the comparison between the horizontal synchronization signal and a binary phase signal, in which, at each parasitic pulse among successive parasitic pulses between two synchronization pulses, the driving signal is successively varied in the increasing direction or in the decreasing direction.

Abstract: In a switching power supply controlled by modulated width pulses obtained by comparison between a saw-tooth voltage (15) oscillating between first and second levels and a servo control voltage (19), the servo control voltage is initially set to a value external to the oscillation interval of the saw-tooth, then, in a first phase, varies up to a first level (dead time) and, in a second phase, varies from the first to the second level for supplying control pulses having progressively increasing widths. A circuit (45, 50) ensures the variation of the servo control voltage during the first phase according to a first slope and then the variation of said servo control voltage during the second phase according to a second slope, lower than the first one, and a circuit (60) causes the slope switching after the detection of the first control pulse.

Abstract: A detection circuit of a line synchronization signal in a video signal wherein the synchronization signal is sent to a phase locked loop (PLL) comprises a voltage controlled oscillator (8), for supplying a line scanning signal to a display. The following steps are provided: inhibiting the operation of the loop and setting the VCO to its free frequency, in the absence of the line synchronization signal; supplying a detection window in relation with the oscillations of the VCO; and detecting the presence of the synchronization signal in this window for supplying either an enabling signal after the detection of a determined number of synchronization tops, this enabling signal connecting again the VCO in the loop, or an inhibiting signal if the detection is interrupted during the determined number of synchronization tops.

Abstract: A detection circuit for a video tape recorder signal on the input of a TV set connected to a line synchronization separating circuit (11) in turn connected to a PLL (12) comprises a first phase comparator (15), the PLL (12) exhibiting a first time constant (I1, C1) corresponding to an operation on a normal TV signal. This circuit further comprises a switch (20) for switching the PLL on a second time constant (3I1, C1) shorter than the first one, a second phase comparator (22) for comparing the input and output phases of the first phase comparator, the second phase comparator being associated with a third time constant (I2, C2) shorter than the first and second ones, a threshold comparator (24) supplying to the switch (20) a control signal when the comparator output (22) is outside determined limits.