Koninklijke Philips Corporation N.V.

U.S. Philips Corporation

Hubertus Cornelis Miermans

Antonius A Marinus

Guy L De Bondt

A power supply apparatus converts an input voltage () into a first () and a second output voltage (). The first () and the second output voltage () are put into and/or out of operation sequentially. The power supply apparatus comprises a first converter unit () which converts the input voltage () into the first output voltage (), and a second converter unit () for providing the second output voltage (). The second converter unit input () is coupled to the first converter unit output (). The second converter unit () can only start and provide an output voltage after the first converter unit () has started. During power-down, a sequence is created in which the second converter unit remains operational until any capacitance coupled to the first converter unit output has been discharged.

Power supply architecture with controlled power-on and power-off sequence

A switched mode power supply apparatus is equipped with a start-up device supplying electrical energy to a controller which controls the switching of a switching transistor. The start-up device is bypassed by a bypass device. During start-up of the power supply, the bypass device is open. After a successful start-up, the bypass device is closed, eliminating further dissipation in the start-up device, and, therefore, increasing the overall energy efficiency of the power supply. By connecting the start-up device to a stand-by power supply or to a primary voltage, use of an additional winding on the transformer to supply the controller is obviated. The power supply has an electronic overload protection, and will stop and periodically attempt a restart when an overload condition occurs.

Start-up circuit for switched mode power supply

In a protection circuit for a plurality of fans, an element is associated with each fan. The impedance or the current value of the element indicates the operation condition of the fan. For example, the impedance or the current value may be low if the fan is operative or functioning normally, and high when the fan is inoperative or functioning abnormally. The elements are arranged in parallel between two conductive lines. A detection circuit determines the total impedance or current value between the two lines. If the total impedance or current is not within a predetermined range which indicates that all fans are operating normally, at least one of the fans functions abnormally. The number of lines required to convey the operation status of the fans to the detection circuit is only two and does not depend on the number of fans involved.

Fan protection

A switched-mode power supply with a burst mode comprises an integrated circuit (Ic) with a minimal number of terminals. The integrated circuit (Ic) comprises a switching element (S) for periodically switching on and off the current (Id) in a primary winding (Lp) of a transformer (T), and a control circuit (Cc) for controlling the on and off-switching of the switching element (S). The integrated circuit (Ic) has three terminals (T,, T,, T,). A main current path of the switching element (S) is arranged between two of the terminals (T,, T,). A capacitor (C,) is connected to the third terminal (T,). A capacitor voltage (Vc) across the capacitor (C,) is used as power supply voltage for the control circuit (Cc). A feedback circuit (Fb) has an input connected to a DC output voltage (Vout) supplied by a secondary winding (Ls) of the transformer (T), and an output connected to the third terminal (T,). The control circuit (Cc) further receives the capacitor voltage (Vc) for periodically switching said main current path on and off when the capacitor voltage (Vc) is in a first range indicating that the power supply voltage (Vout) is lower than the predetermined value (Vp), and for keeping said main current path in a non-conductive state when said capacitor voltage (Vc) is in a second range indicating that the power supply voltage (Vout) exceeds the predetermined value (Vp).

Switched-mode power supply with capacitor controlled power supply

A switched-mode power supply specially suitable for supplying a low output power. The switched-mode power supply periodically first charges a capacitor (C) from an input voltage (Vin) during a first period of time (T1), and then forms a resonant circuit, including the capacitor (C) and an inductor (L), to transfer the charge in the capacitor (C) to a load (Z) via a rectifier during a second period of time (T2).

Switched-mode power supply for charging a capacitance during a first

A switched-mode power supply circuit having a transformer and a first controllable switch on the primary side of the transformer. A first section is in the form of a flyback d.c. converter including a first secondary winding of the transformer for generating a first d.c. output voltage which is stabilized, by a control, against d.c. input voltage variations of the circuit and of a first load. A second section including a second secondary winding of the transformer constitutes a forward d.c. converter having a second controllable switch for generating a second d.c. output voltage. The ratio between the period of conductance of the second switch and the period of the control signal of the first switch is independent of the frequency of this signal.

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Eindhoven, Netherlands

Hubertus Cornelis Miermans