Circuit arrangement and method of driving a circuit arrangement
First Claim
1. A method of driving a circuit arrangement with at least one first electrical device and at least one second electrical device connected in series therewith, by means of a semiconductor switch for controlling said first electrical device, the semiconductor switch comprising at least a gate (g), a source (s) and a drain (d), and connected in parallel with said first electrical device by means of the drain and the source, wherein said second electrical device is present downstream of said first electrical device and said semiconductor switch, in the direction of a current flow when the circuit arrangement is in use, the method comprisingproviding a first control signal between the gate (g) and the source (s), that switches the semiconductor switch, in order to control the first electrical device;
- providing a second control signal to control the second electrical device, the second control signal being determined in dependence on the first control signal, wherein providing the first control signal comprises providing a resistive element between the gate (g) and the source (s) and providing a current signal through the resistive element, and wherein the second control signal is determined in dependence on the value of the current signal.
3 Assignments
0 Petitions
Accused Products
Abstract
The present invention relates to controlling switches in a series connection of electrical devices, in particular to a circuit arrangement, and method of operating same, in which a transistor switch (44, 54) is used to control operation of the devices (12, 14). Because the transistor switches need a gate-source voltage difference, but on the other hand are connected with their source (s) and drain (d) to the main circuit branch, this voltage difference is built up by providing a control current (Ii, I2) over e.g. a resistor (42, 52). This control current (Ii, I2) enters the main current (I), which would influence the operation of the devices, e.g. LEDs (12, 14). In order to correct this, the control current (I2) is corrected for the values of one or more upstream control currents (I2), e.g. through adapting the pulse width in pulse width modulation.
18 Citations
5 Claims
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1. A method of driving a circuit arrangement with at least one first electrical device and at least one second electrical device connected in series therewith, by means of a semiconductor switch for controlling said first electrical device, the semiconductor switch comprising at least a gate (g), a source (s) and a drain (d), and connected in parallel with said first electrical device by means of the drain and the source, wherein said second electrical device is present downstream of said first electrical device and said semiconductor switch, in the direction of a current flow when the circuit arrangement is in use, the method comprising
providing a first control signal between the gate (g) and the source (s), that switches the semiconductor switch, in order to control the first electrical device; providing a second control signal to control the second electrical device, the second control signal being determined in dependence on the first control signal, wherein providing the first control signal comprises providing a resistive element between the gate (g) and the source (s) and providing a current signal through the resistive element, and wherein the second control signal is determined in dependence on the value of the current signal. - View Dependent Claims (2, 3)
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4. A circuit assembly, comprising
a connection for an electrical power source for supplying an electrical current to the circuit assembly, a first electrical device and a second electrical device, connected in series with the first electrical device, a semiconductor switch configured to control the first electrical device, the semiconductor switch comprising a gate (g), a source (s) and a drain (d), and connected in parallel with said first electrical device via the drain (d) and the source (s), a control unit configured to supply a first control signal to the semiconductor switch and a second control signal to said second electrical device, wherein the second electrical device is connected to the first electrical device and the semiconductor switch, and a resistor provided between the gate (g) and the source (d), wherein a voltage difference develops when a current (I1, I2) travels through the resistor, wherein the first control signal comprises a control current signal to the gate (g) and to the resistor, wherein the control unit is arranged to adapt the second control signal in dependence on the first control signal.
Specification