METHOD AND APPARATUSES FOR CONTROLLING THE OUTPUT VOLTAGE OF A VOLTAGE REGULATOR

Abstract

A device comprises a voltage regulator, circuits, a voltage-to-current converter, a control bus, a resistor and a resistor network. Each of the circuits has at least one LED connector and one LED driver. Each of the circuits has a measuring circuit for detecting voltage differences between the potentials of LED terminals and a reference potential. Further, each of the circuits includes a local controller. The local controller withdraws a current from the control bus in dependence on the detected voltage differences. Bias current sources inject bias currents into the control bus in form of a sum current of the injected bias currents. The resistor performs a current-to-voltage conversion of the sum current to a control voltage. The voltage-to-current converter converts the control voltage into a current. The resistor network converts the current into a voltage value. An output voltage of the voltage regulator depends on the voltage value.

Claims

1. A method for regulating an output voltage at an output of a voltage regulator for supplying a lighting device with electrical energy, wherein the lighting device includes at least two circuits, the at least two circuits including a first circuit and a second circuit, wherein each of the at least two circuits is constructed to supply at least one LED group with electrical energy by a current source associated to the LED group, and wherein the current source is a LED driver, the method comprising: generating the output voltage by the voltage regulator at the output; setting of a first LED group current through the at least one LED group by the current source of the first circuit associated with the respective LED group of the first circuit; setting of a second LED group current through the at least one LED group by the current source of the second circuit associated with the respective LED group of the second circuit; if necessary, setting of a third LED group current through an at least one further LED group by the current source of the possibly further circuit associated to this further LED group; detecting respective voltage drops across the respective current sources of the LED groups as the respective voltage drop values of the current source within the respective circuits, wherein a separate voltage drop value is detected for each current source; selecting the respective voltage drop value of one of the respective current sources of each circuit from the voltage drop values of the current sources of the respective circuit as a characteristic voltage drop value of the circuit; withdrawing of a respective withdrawal current of the respective circuit from a control bus by each of these circuits, wherein an amount of the respective withdrawal current of the respective circuit depends on a deviation of its characteristic voltage drop value from a set value, and all of the withdrawal currents and at least one optional constant bias current are summed to a total current, and regulating the output voltage of the voltage regulator at its output as a function of the sum current.

2. A device for supplying at least two LED groups with electrical energy comprising: a voltage regulator, at least two circuits, a voltage-to-current-converter, a control bus, a resistance, and a resistance network, wherein each of the circuits has at least one LED connection for at least one LED group, each of the circuits has at least one LED driver per LED group for the energy supply of the LED group via the LED connection associated with the respective LED group, each of the circuits has at least one measuring device of the circuit for detecting voltage differences between potentials of the LED connections of the circuit and a reference potential, each of the circuits comprises a local controller, wherein: the local controller withdraws a current from the control bus by a driver in dependence on the voltage differences detected by the measuring device, one or more bias current sources feeds one or more bias currents in form of a sum current of the fed bias currents into the control bus, the resistor performs a current-to-voltage conversion of the sum current into a control voltage, the voltage-to-current converter converts the control voltage into a current of a voltage control signal, the resistor network converts the current of the voltage control signal into a voltage value, and an output voltage of the voltage regulator depends on the voltage value.

3. A device for supplying at least two LED groups with electrical energy, the device comprising: a voltage controlled voltage regulator, at least two circuits, a control bus, and a resistor, wherein each of the circuits includes at least one LED terminal for at least one LED group, each of the circuits includes at least one LED driver per LED group for supplying power to LED group via the LED terminal associated with the LED group, each of the circuits includes at least one measuring circuit of the circuit for detecting voltage differences between potentials of the LED terminals of the circuit and a reference potential, each of the circuits includes a local regulator, wherein the local regulator withdraws a current from the control bus by at least one driver in dependence on the voltage differences detected by its measuring circuit, one or more bias current sources feed one or more respective bias currents into the control bus in form of a sum current of the fed bias currents, the resistor performs a current-to-voltage conversion of the sum current into a control voltage, and an output voltage of the voltage regulator depends on the value of the control voltage.

4. A device for supplying at least two LED groups with electrical energy, the device comprising: a current controlled voltage regulator, at least two circuits, and a control bus, wherein each of the circuits comprises at least one LED connection for at least one respective LED group, each of the circuits includes at least one LED driver per LED group for supplying power to the LED group via the LED connection associated with the LED group, each of the circuits includes at least one measuring circuit of the circuit for detecting voltage differences between potentials of LED terminals of the circuit and a reference potential, each of the circuits includes a local controller, wherein the local controller withdraws a current from the control bus by at least one driver in dependence on the voltage differences detected by its measuring means, one or more bias current sources feed one or more bias currents into the control bus in form of a sum current of the fed bias currents, the resistor performs a current-to-voltage conversion of the sum current into a control voltage, and an output voltage of the voltage regulator depends on the value of the sum current.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG. 1 shows an exemplary device for regulating a voltage regulator for supplying at least two LED groups.

DESCRIPTION

[0035] The disclosure relates to a method for regulating the output voltage (V.sub.0) at the output (V.sub.out) of a voltage regulator (VREG) for supplying a lighting device with electrical energy, wherein the lighting device comprises several, but at least two, circuits (IC1, IC2) with at least one LED group (LED.sub.1, LED.sub.2, LED.sub.3) and an appropriate current source (LED DRV) per circuit (IC1, IC2).

[0036] The method, shown in FIG. 1, comprises at least the following steps:

[0037] First, a supply voltage (V.sub.0) is generated by means of the voltage regulator (VREG) at the output (V.sub.out) of this voltage regulator (VREG).

[0038] Next, a respective LED group current (I.sub.LED1, I.sub.LED2, I.sub.LED3) is set by the LED groups (LED.sub.1, LED.sub.2, LED.sub.3) by means of a current source (LED DRV) for each LED group (LED.sub.1, LED.sub.2, LED.sub.3). In the example of FIG. 1, the LED groups (LED.sub.1, LED.sub.2, LED.sub.3) are distributed on two circuits (IC1, IC2). Devices having more than two circuits and more than three LED groups are expressly intended to be included in the claims and to be considered as disclosed herein.

[0039] Next, the detection of the respective voltage drop across respective current sources (LED DRV) of the LED groups (LED1, LED2, LED3) is performed as the respective voltage drop value of this current source (LED DRV). This is preferably done in each of the circuits (IC1, IC2) for preferably each of the current sources (LED DRV).

[0040] Next, in preferably each circuit (IC1, IC2), a voltage drop value of the voltage drop values of the current sources (LED DRV) of this circuit is selected as the characteristic voltage drop value of this circuit from among the voltage drop values determined for this circuit. Thus, one characteristic voltage drop value is preferably obtained for each circuit. It is performed as nothing else than determining a respective voltage drop value of a current source (LED DRV) of each circuit (IC1, IC2) from the voltage drop values of the current sources (LED DRV) of that respective circuit (IC1, IC2) as a characteristic voltage drop value of that circuit (IC1, IC2). Preferably, the characterizing voltage drop value of this circuit (IC1, IC2) is the minimum voltage drop value of the determined voltage drop values of this circuit (IC1, IC2).

[0041] Next, each of the circuits (IC1, IC2) draws an electric current associated with it, its draw current, from a control bus (RB). This represents a withdrawal of a respective withdrawal current of the respective circuit (IC1, IC2) from a control bus (RB) by each of these circuits (IC1, IC2). The amount of this respective withdrawal current of the respective circuit (IC1, IC2) is to depend thereby on the deviation of its characteristic voltage drop value from a set value. This setpoint is preferably common to all circuits and thus selected or set the same for all circuits (IC1, IC2) within a tolerance interval.

[0042] Preferably, each circuit (IC1, IC2) feeds a substantially constant bias current (I.sub.Bias) into the control bus (RB). However, a single injection is usually sufficient for proper operation. Theoretically, solutions without bias current injection are also conceivable with greater circuitry effort, but are not preferred here.

[0043] By feeding the current into the control bus (RB), all extraction currents and at least one optional constant bias current (I.sub.Bias) are summed up to a common sum current (I.sub.S). Thus is disclosed a low-effort, easy and inexpensive to implement generation of a common sum current and its subsequent use as a control signal. The output voltage (V.sub.0) of the voltage regulator (VREG) is then regulated at its output (V.sub.out) as in dependence of the sum current (I.sub.S). In the example of FIG. 1, several current-voltage conversions and voltage-current conversions are performed for circuit reasons. Theoretically, however, direct control of the voltage regulator with this current signal is conceivable if the voltage regulator has a current input for controlling its reference value. In the example of FIG. 1, however, a voltage input for the voltage regulator (VREG) is assumed.

[0044] The corresponding device for supplying several, but at least two LED groups (LED.sub.1, LED.sub.2, LED.sub.3) with electrical energy therefore preferably comprises a voltage regulator (VREG), at least two circuits (IC1, IC2), a voltage-to-current converter (VC-C), a control bus (RB), a resistor (R.sub.GPIO) and a resistor network (R1, R2). Each of the circuits (IC1, IC2) preferably has at least one LED connection (LED0, LED1) for at least one LED group (LED.sub.1, LED.sub.2, LED.sub.3), at least one LED driver (LED DRV) per LED group (LED.sub.1, LED.sub.2, LED.sub.3) for supplying power to this LED group (LED.sub.1, LED.sub.2, LED.sub.3) via an LED connection (LED0, LED1) associated with this LED group (LED.sub.1, LED.sub.2, LED.sub.3) and at least one measuring means (ADC) of this circuit (IC1, IC2) for detecting the voltage differences between the potentials of LED connections (LED0, LED1) of this circuit (IC1, IC2) and a reference potential (GND). Furthermore, each of the circuits (IC1, IC2) has a local controller (VR) which, by means of at least one driver (DRV), draws a current from the control bus (RB) depending on the voltage differences detected by its measuring means (ADC). One or more bias current sources (IQ) inject one or more bias currents (I.sub.Bias) into the control bus (RB) in the form of a sum current of the injected bias currents (I.sub.Bias) in order to set the operating point correctly. The resistor (R.sub.GPIO) performs a current-to-voltage conversion of the sum current (I.sub.S) into a control voltage (V.sub.R). The voltage-to-current converter (VC-C) converts the control voltage (V.sub.R) into a current of a voltage control signal (VCTR). The resistor network (R1, R2) converts the current of the voltage control signal (VCTR) into a voltage value (V.sub.ADJ) The output voltage (V.sub.0) of the voltage regulator (VREG) depends on the voltage value (V.sub.ADJ), so that this then closes the control loop. Preferably, the dependencies are linear.

[0045] The control chain of FIG. 1 can be massively shortened.

[0046] The corresponding device simplified in a first step for supplying several, but at least two LED groups (LED.sub.1, LED.sub.2, LED.sub.3) with electrical energy therefore preferably comprises a voltage regulator (VREG), at least two circuits (IC1, IC2), a control bus (RB), and a resistor (R.sub.GPIO). Each of the circuits (IC1, IC2) preferably has at least one LED connection (LED0, LED1) for at least one LED group (LED.sub.1, LED.sub.2, LED.sub.3), at least one LED driver (LED DRV) per LED group (LED.sub.1, LED.sub.2, LED.sub.3) for supplying power to this LED group (LED.sub.1, LED.sub.2, LED.sub.3) via the LED connection (LED0, LED1) associated with this LED group (LED.sub.1, LED.sub.2, LED.sub.3) and at least one measuring means (ADC) of this circuit (IC1, IC2) for detecting the voltage differences between the potentials of LED connections (LED0, LED1) of this circuit (IC1, IC2) and a reference potential (GND). Furthermore, each of the circuits (IC1, IC2) has a local controller (VR) which, by means of at least one driver (DRV), draws a current from the control bus (RB) depending on the voltage differences detected by its measuring means (ADC). One or more bias current sources (IQ) inject one or more bias currents (I.sub.Bias) into the control bus (RB) in the form of a sum current of the injected bias currents (I.sub.Bias) in order to set the operating point correctly. The resistor (R.sub.GPIO) performs a current-voltage conversion of the sum current (I.sub.S) into a control voltage (V.sub.R). The output voltage (V.sub.0) of the voltage regulator (VREG) depends on the voltage value of the control voltage (V.sub.R), so that this then closes the control loop. Preferably, the dependencies are linear.

[0047] This control chain can be further shortened.

[0048] The corresponding device simplified in a second step for supplying electrical energy to several, but at least two LED groups (LED.sub.1, LED.sub.2, LED.sub.3) preferably comprises a voltage regulator (VREG), at least two circuits (IC1, IC2), and a control bus (RB). Each of the circuits (IC1, IC2) preferably has at least one LED connection (LED0, LED1) for at least one LED group (LED.sub.1, LED.sub.2, LED.sub.3), at least one LED driver (LED DRV) per LED group (LED.sub.1, LED.sub.2, LED.sub.3) for supplying power to this LED group (LED.sub.1, LED.sub.2, LED.sub.3) via the LED connection (LED0, LED1) associated with this LED group (LED.sub.1, LED.sub.2, LED.sub.3) and at least one measuring means (ADC) of this circuit (IC1, IC2) for detecting the voltage differences between the potentials of LED connections (LED0, LED1) of this circuit (IC1, IC2) and a reference potential (GND). Furthermore, each of the circuits (IC1, IC2) has a local controller (VR) which, by means of at least one driver (DRV), draws a current from the control bus (RB) depending on the voltage differences detected by its measuring means (ADC). One or more bias current sources (IQ) feed one or more bias currents (I.sub.Bias) in the form of a sum current (I.sub.S) of the fed bias currents (I.sub.Bias) into the control bus (RB) in order to set the operating point correctly. The output voltage (V.sub.0) of the voltage regulator (VREG) depends on the current value of the sum current (I.sub.S), so that this then closes the control loop. Preferably, the dependencies are linear. A current-controlled voltage regulator is required here.

[0049] A device according the disclosure allows a regulation of the voltage regulator (VREG) in a simple manner in order to supply more complex LED arrangements supplied with electrical energy from several circuits. It was recognized that this is particularly easy with a current-controlled voltage regulator. Here, the total current (I.sub.s) is the actual value signal and the input of the voltage-to-current converter (VC-C) is the exemplary input of a current controlled voltage regulator advanced by a said component (VREG, R1, R2, VC-C). In contrast to the state of the art, the construction is particularly robust against EMC radiation and potential offset due to the current-controlled signal.

LIST OF REFERENCES

[0050] ADC analog-to-digital converter, also known as measuring equipment [0051] ADJ Control input of the voltage regulator (VREG) for the voltage control signal (VCTR) [0052] I.sub.ADJ additional current [0053] I.sub.Bias Constant current of the respective bias current source (IQ), which is supplied via the control bus connection of the respective integrated circuit (IC1, IC2) is fed into the control bus (RB). The bias current is preferably a current that is constant over time for setting the operating point of the proposed device. [0054] IC1 first integrated circuit [0055] IC2 second integrated circuit [0056] IQ bias current source of an integrated circuit (IC1, IC2) [0057] I.sub.S sum current of the fed bias currents (I.sub.Bias) of all integrated circuits (IC) connected to the control bus (RB) [0058] GND reference potential [0059] GPIO control bus connection of the associated integrated circuit (IC1, IC2) [0060] OP1 amplifier [0061] LED.sub.1 first LED; first group of LEDs [0062] LED.sub.2 second LED; second group of LEDs [0063] LED.sub.3 third LED; third group of LEDs [0064] LED.sub.3a first LED of the third LED group (LED.sub.3) [0065] LED.sub.3b second LED of the third LED group (LED.sub.3) [0066] LED0 first LED connection [0067] LED1 second LED connection [0068] LED DRV LED driver [0069] R1 first resistance [0070] R2 second resistance [0071] R3 third resistor [0072] RB control bus [0073] R.sub.i internal control signal [0074] RS control signal [0075] R.sub.GPIO resistance to convert the sum current (I.sub.S) into a voltage [0076] T1 first transistor [0077] V.sub.0 Output voltage of the voltage regulator (VREG) at his voltage regulator output (V.sub.out) against the reference potential (GND) [0078] V.sub.ADJ Voltage value of the voltage control signal (VCTR) against a reference potential (GND) [0079] VC-C voltage-to-current converter (external voltage to current converter), which is preferably not part of the integrated circuits (IC1, IC2) and/or of the voltage regulator (VREG) and which can consist, for example, of a first transistor (T1), an amplifier (OP1) and a third resistor (R3). [0080] VCTR voltage control signal [0081] V.sub.R Control voltage at the resistor (R.sub.GPIO) [0082] VR local controller of an associated integrated circuit (IC1, IC2) [0083] VREG voltage regulator [0084] V.sub.out voltage regulator output of the voltage regulator (VREG)

LIST OF CITED DOCUMENTS

[0085] DE 10318780 A1 [0086] DE 102005028403 B4 [0087] DE 102006055312 A1 [0088] EP 1499165 B1 [0089] EP 2600695 B1 [0090] U.S. Pat. No. 7,157,866 B2 [0091] U.S. Pat. No. 8,319,449 B2 [0092] U.S. Pat. No. 8,519,632 B2 [0093] US 2007/0139317 A1 [0094] US 2008/0122383 A1 [0095] US 2009/0230874 A1 [0096] US 2010/0026209 A1 [0097] US 2010/0201278 A1 [0098] US 2011/0012521 A1 [0099] US 2011/0043114 A1 [0100] US 2012/0268012 A1 [0101] WO 2013/030047 A1