Thomson Multimedia S.a.

Thomson Licensing

Thomson Licensing S.a.

Thomas Licensing S.a.

Deutsche Thomson-brandt Gmbh

Kum Yoong Zee

Seng Huat Ng

Kian Meng Koh

Markus Rehm

Thomas Riesle

Choon Meng Chan

Jose Ignacio Rodriquez-Duran

José-I Rodriguez-Duran

The arrangement and the respective display unit comprise a microprocessor, a demagnetization circuit and a switched mode power supply operating in a normal mode and in a low power mode. The microprocessor is coupled via the same output to the switched mode power supply for controlling the low power mode and to the demagnetization circuit for controlling a demagnetization operation. In a preferred embodiment, the control signal from the microprocessor provides a control for a low power burst mode, and is further combined with a power on-indicative signal via a logical AND combination for controlling the demagnetization circuit.

System for controlling low power mode of TV by using single output pin of microprocessor to send signals to demagnetization circuit and switched mode power supply

The protection circuit comprises a clamping circuit with a switching element for reducing a supply voltage in case of an over voltage condition, and a holding circuit for providing a holding current for the clamping circuit. The clamping circuit comprises a threshold circuit, which provides a switching voltage for a switching element when the supply voltage reaches an upper voltage limit. The switching element is connected to a charge capacitor, which provides the switching-on voltage for the switching transistor, and by reducing this supply voltage, the switching of the switching transistor is disabled. The holding circuit comprises in particular a capacitor, which is coupled via a resistor to the clamping circuit for providing an additional current in case of an over voltage condition.

Protection circuit for a switched mode power supply

A switched-mode power supply with a control loop and a microprocessor has a normal mode and a low-power mode with a burst mode. The microprocessor is connected via an output to the control loop and uses this to control the burst mode of the switched-mode power supply directly. The control loop of the switched-mode power supply monitors, in particular, a secondary output voltage, so that the output of the microprocessor is connected to the control loop, for example via a simple resistor network or a transistor stage. The clock frequency and the duty cycle of the burst mode are permanently stored in the microprocessor and can be defined for the switched-mode power supply directly, for example using TTL logic.

Arrangement having a switched-mode power supply and a microprocessor

The protection circuit comprises a storage capacitor which is coupled with a terminal of a secondary winding which charges said storage capacitor during the on-interval of the switching transistor. During the off-interval of the switching transistor the charge of the storage capacitor is fed to the driver stage or the control capacitor for closing or keeping closed the switching transistor when one of the secondary windings has a short circuit.

Protection circuit for a switched-mode power supply

The invention is about a dc/dc converter (1) fitted with switching means (11, 12) having a drive electrode (13, 14) each drive electrode (13, 14) being connected to polarization means (49,50). The switching means are to switch on and off a current coming from a direct source of current 2 and circulating in windings (17, 18, 5) of transformers (6, 7) of the converter. The improvement according to the invention comprises a protection circuit 24 connected to means (44) for detecting the value of current circulating in one of the windings (4, 5, 15, 19, 23) of the transformers. Outputs (47, 48) of circuit 24 are connected to the drive electrode (13, 14) of switching means (11, 12). Protection circuit (24) may be a bistable circuit that will lower voltage at its outputs (47, 48) in a permanent way if detected current has been to high, thus switching off in a permanent way switching means (11, 12). The switching off is made in less than a working period of the switching means (11, 12) and prevent any damage to said switching means.

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Johor, Malaysia

Kum Yoong Zee