A power control circuit comprising a power supply and a load, the load being synthesized from an impedance synthesizer comprising two-terminal impedance elements connected in series and grouped in impedance modules. The impedance elements in each impedance module are of equal value, while those between the modules bear ratios uniquely defined according to the numbers of impedance elements in the impedance modules. A number of switches associated with said impedance elements short out a selected number of the impedance elements under the control of a first analog signal which may be preprocessed by an analytic function. The analog signal is converted to digital signals by an analog-to-digital converter, then level shifted to control the switches associated with the impedance elements, whereby the amount of power delivered to the load is controllable by the first analog signal. Pulse-width-modulation is deployed to further control the power by a second analog signal, with additional benefit of overload protection.

An electrically switched power converter (10) for converting a direct current (DC) supply voltage (Vin) into at least three balanced DC output load voltages (V1, V2, . . . , Vn). The power converter (10) comprises a switching network (12) having a plurality of series connected electrically controllable switches (S1, S2, . . . , Sn). An output network (11) having a plurality of series connected capacitors (C1, C2, . . . , Cn) for providing said DC output load voltages. A plurality of inductors (L1, L2, . . . , Ln−1), and an electronic controller (14). The electronic controller (14) operates the switches of the switching network (12) for balancing the output load voltages (V1, V2, . . . , Vn) within a range of output load voltages based on a measured representation of the output load voltages and/or output load currents (Io.sub.1, Io.sub.2, . . . , Io.sub.n), by forming respective parallel connections of capacitors (C1, C2, . . . , Cn) and inductors (L1, L2, . . . , Ln−1).

An electrically switched power converter (10) for converting a direct current (DC) supply voltage (Vin) into at least three balanced DC output load voltages (V1, V2, . . . , Vn). The power converter (10) comprises a switching network (12) having a plurality of series connected electrically controllable switches (S1, S2, . . . , Sn). An output network (11) having a plurality of series connected capacitors (C1, C2, . . . , Cn) for providing said DC output load voltages. A plurality of inductors (L1, L2, . . . , Ln−1), and an electronic controller (14). The electronic controller (14) operates the switches of the switching network (12) for balancing the output load voltages (V1, V2, . . . , Vn) within a range of output load voltages based on a measured representation of the output load voltages and/or output load currents (Io.sub.1, Io.sub.2, . . . , Io.sub.n), by forming respective parallel connections of capacitors (C1, C2, . . . , Cn) and inductors (L1, L2, . . . , Ln−1).

A first flying capacitor circuit and a second flying capacitor circuit are connected in series so as to be in parallel to a high voltage side DC part. A reactor is connected to a positive side terminal of a low voltage side DC part and a midpoint of the first flying capacitor circuit. A midpoint of the second flying capacitor circuit is connected to a negative side terminal of the low voltage side DC part. A node between the first flying capacitor circuit and the second flying capacitor circuit is connected to an intermediate potential node of the high voltage side DC part.

Disclosed are a voltage compensation method and device of a voltage reducing circuit. The voltage compensation method includes: determining a capacitance value of each capacitor and a resistance value of each resistor in a voltage compensation circuit according to a voltage compensation expectation of the voltage reducing circuit; determining each zero and each pole of a transfer function of the voltage compensation circuit according to the capacitance value of each capacitor and the resistance value of each resistor; setting each capacitor and the resistor not in direct connection with the capacitor in series to have a positive temperature coefficient, and setting the resistor in direct connection with the capacitor in series to have a negative temperature coefficient; and compensating voltage for the voltage reducing circuit by using the voltage compensation circuit to output a rated voltage.

Disclosed are a voltage compensation method and device of a voltage reducing circuit. The voltage compensation method includes: determining a capacitance value of each capacitor and a resistance value of each resistor in a voltage compensation circuit according to a voltage compensation expectation of the voltage reducing circuit; determining each zero and each pole of a transfer function of the voltage compensation circuit according to the capacitance value of each capacitor and the resistance value of each resistor; setting each capacitor and the resistor not in direct connection with the capacitor in series to have a positive temperature coefficient, and setting the resistor in direct connection with the capacitor in series to have a negative temperature coefficient; and compensating voltage for the voltage reducing circuit by using the voltage compensation circuit to output a rated voltage.

A driving circuit turns on and off a driving current I.sub.LED that flows through a light source, so as to control the lighting on/off state of the light source. A judgment circuit compares a voltage V.sub.LED across the light source with a threshold value, and judges the lighting on/off state of the light source based on the comparison result. A first resistor R is provided in parallel with the light source.

A driving circuit turns on and off a driving current I.sub.LED that flows through a light source, so as to control the lighting on/off state of the light source. A judgment circuit compares a voltage V.sub.LED across the light source with a threshold value, and judges the lighting on/off state of the light source based on the comparison result. A first resistor R is provided in parallel with the light source.

A voltage generator circuit can be structured to provide an output voltage having a substantially flat temperature coefficient by use of a circuit loop having transistors and a resistor arranged such that, in operation, current through the resistor has a signed temperature coefficient. The current behavior can be controlled by an output transistor coupled to another transistor, which is coupled to the circuit loop, with this other transistor sized such that, in operation, a voltage of this other transistor has a signed temperature coefficient that is opposite in sign to the signed temperature coefficient of the current through the resistor. Embodiments of voltage generator circuits can also include additional components to trim output voltage, to provide unconditional stability, or other features for the respective voltage generator circuit. In various embodiments, a voltage generator circuit can be implemented as a low drop-out (LDO) voltage regulator.

A switch mode power supply includes a bootstrap circuit, control circuits, and an auxiliary winding coupled to the bootstrap circuit and configured to supply power to the control circuits after startup of the power supply. The bootstrap circuit is configured to supply power to the control circuits during startup and includes an isolation circuit to limit current flow between the starting capacitor and the control circuits while the starting capacitor is charged to a starting voltage by the high voltage input. During the initial charge of the starting capacitor, the control circuits do not have power to provide the initial functionality of the power supply. Once the starting capacitor is charged to the starting voltage, the isolation circuit is activated to allow current flow that powers the control circuits during the remainder of the startup until the auxiliary winding is able to power the control circuits.