Method and device for adjusting a voltage supply device for a multichannel LED control and power supply device

Abstract

A method for adjusting a voltage supply device for a multichannel LED control and power supply device having a determination of a number of LEDs that are connected to a multichannel LED control and power supply device or are a part of this device and that are switched on and supplied with current by the multichannel LED control and power supply device at a point in time, and a setting of a voltage with which the multichannel LED control and power supply device is supplied as a function of the number of LEDs determined that are switched on and supplied with current.

Claims

1. A method for adjusting a voltage supply device for a multichannel LED control and power supply device, the method comprising: determining a number of LEDs that are connected to a multichannel LED control and power supply device or are a part of this device and that are switched on and supplied with current by the multichannel LED control and power supply device at a point in time; and setting a voltage with which the multichannel LED control and power supply device is supplied as a function of the number of LEDs determined that are switched on and supplied with current, wherein switching states of the LEDs to be switched on or off in a next time slot are entered into a register and during entering of the switching states into the register, a counter counts how many of the LEDs are to be switched on, wherein once entry of the switching states into the register is completed, the switching states of the register are transferred to another register and current sources are then adjusted according to the switching states, and wherein at a same time as the switching states being transferred from the register to the another register, a voltage for supplying the multichannel LED control and power supply device is set as a function of a value of the counter due to a signal provided by the counter.

2. The method according to claim 1, wherein the counter is incremented when an LED is switched on and is decremented when an LED is switched off, or is only incremented from an initial value when an LED is switched on, or is only decremented from an initial value when an LED is switched off.

3. The method according to claim 1, wherein the voltage V.sub.A that is provided at an output of the voltage supply device to supply the multichannel LED control and power supply device is determined as follows:
V.sub.A=V.sub.Fmax+V.sub.Q+n*I*R.sub.L wherein V.sub.A: is the voltage at the output of the voltage supply device, V.sub.Fmax: is the maximum forward voltage of all the LEDs connected to the multichannel LED control and power supply device, V.sub.Q: is the voltage required by the multichannel LED control and power supply device for setting the output currents for the LEDs, n: is the number of LEDs that are switched on, I: is the current of an individual LED, and R.sub.L: is the ohmic resistance between the output of the voltage supply device and the input of the multichannel LED control and power supply device.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawing which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein the sole FIGURE is a block diagram illustrating and exemplary arrangement according to the invention.

DETAILED DESCRIPTION

(2) The FIGURE illustrates a greatly simplified block diagram of an arrangement including a multichannel LED control and power supply device, a voltage supply device for the multichannel LED control and power supply device, and a control unit for the voltage supply device.

(3) The arrangement according to the invention has a multichannel LED control and power supply device 1, a voltage supply device 2 for the multichannel LED control and power supply device 1, and a control unit 3 for the voltage supply device 2.

(4) The voltage supply device 2 can be connected to a DC network, for example to a vehicle electrical system of a motor vehicle. The voltage supply device 2 converts a primary DC voltage at an input side into a secondary DC voltage at the output side. A desired value for the secondary DC voltage is specified by the control unit 3.

(5) The secondary DC voltage supplies the multichannel LED control and power supply device 1. This has a number N of LEDs 10 that are supplied with current by N current sources 11. The current sources 11 can be switched on and off in order to switch the connected LEDs 10 on and off.

(6) The switching state of the LEDs 10 or of the current sources 11 is specified by a first register 12. Whether an LED 10 is switched on or not is specified in the first register 12.

(7) The values in the first register 12 are specified from the outside. To enter the values into the first register 12, a second registera shift register 13is used initially. From the outside, the desired switching states are entered serially into the shift register 13 through an input SI of the multichannel LED control and power supply device 1. Once N desired switching states have been entered into the shift register 13, the content of the shift register 13 is transferred into the first register 12 by means of a signal at an input UPD of the multichannel LED control and power supply device 1, which has the immediate result that the current sources 11 are adjusted according to the desired switching states specified in the first register 12.

(8) At the same time as the transfer of the register content into the first register, the voltage provided by the voltage supply device 2 to supply the multichannel LED control and power supply device 1 is matched to the power requirement of the current sources. To this end, the control unit 3 of the voltage supply device 2 receives a signal from the multichannel LED control and power supply device 1 that indicates how many LEDs 10 are switched on. The signal is provided by a counter 14.

(9) Upon initialization of the shift register 13, the counter 14 counts how many LEDs 10 should be switched on. For every LED 10 that should be switched on, the counter is correspondingly incremented from zero. Once the signal for transferring the register content from the shift register 13 into the first register 12 is present at the input UPD, the counter state is transmitted to the control unit 3 by the counter 14, and the counter state is reset to zero.

(10) The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims: