DE202018006170U1 - Binning resistor for detecting the LED ringing of a remote board and the board temperature - Google Patents

Abstract

Device with a main circuit carrier (PCB1) and- with a remote circuit carrier (PCB, PCB) and- with a binning resistor (R, R) and- with a connectable LED string and- with a voltage measuring device and- with a LED Driver (LEDDRV) and- if necessary, with a microcomputer (MCU) and- where the LED driver (LEDDRV) has a current source output (k, k) and - where the current source output (k, k) of the LED driver (LEDDRV) to the Actuation of the connectable LED string is suitable and provided, which is located on a main circuit board (PCB), and- wherein the main circuit carrier (PCB) and the remote circuit board (PCB, PCB) are mechanically offset from each other and wherein the voltage measuring device to the current source output ( k, k) can be assigned and wherein the voltage measuring device is provided for monitoring the LED function of the relevant, connectable LED string and wherein the voltage measuring device for energizing the binning resistor (R, R) is suitable and wherein the binning resistor (R, R) is located on the remote circuit board (PCB, PCB), and wherein the voltage measuring device is a value of the voltage drop in the form of a value of binning Voltage (V, V) across the binning resistor (R, R) during energization, and wherein the LED driver and / or the microcomputer (MCU) determines this value as determined by the voltage measuring device during energization of the binning resistor. Resistors (R, R) has been determined, at least in times when the said energization does not take place, stores and wherein the LED driver (LEDDRV) the average value of an electric current (i, i) for supplying a respective LED strand ( LEDS, LEDS) by means of a further current source output (k, k) of the LED driver (LEDDRV), which is connected to the relevant LED string (LEDS, LEDS), as a function of the determined value of the voltage drop across the binning resistor ( R, R) and wherein the respective LED string (LEDS2, LEDS3) is located on the remote circuit carrier (PCB2, PCB3) and wherein the binning resistor is characterized by a series circuit consisting of a first resistor and a second resistor, and wherein the temperature coefficient of the first resistor is greater than that of the second resistor or wherein the temperature coefficient of the first resistor is negative and that of the second resistor is positive.

Description

preamble

The invention is directed to a method for detecting and using the LED ringing of a remote circuit carrier (PCB2, PCB3) with an LED string ( LEDS ₂ . LEDS ₃ ).

General introduction

LED drivers today usually consist of a power source that supplies the LEDs of a LED string with electric current of a defined size. Currently, this LED string current is usually configured via an external high-impedance reference resistor which determines the value of the current of said current source. Multi-channel drivers, which can drive multiple LED strings, preferably nowadays have a power source per LED string, which supplies the respective LED string with electric current. Typically, today, the value of all the currents of all current sources is set to be the same and the same at the same time over a single resistor for all channels. For individual adjustment, one power source and one resistor are required per channel. Both the prior art and the proposal disclosed herein are explained below with reference to the figures, without limiting the claimed scope thereto. The figures are simplified drawings which illustrate schematically the disclosed technical teaching so far that a person skilled in the art can understand them.

FIG. 1

1 FIG. 3 shows an exemplary LED driver device of the prior art (FIG. SdT ), as offered for example by the company Texas Instruments. An LED driver ( LEDDRV ) is performed by an exemplary microcomputer ( MCU ) by means of an exemplary data bus ( DB ) controlled.

A voltage source ( V _sup ) supplies the operating voltage ( V ₀ ). Via a supply voltage line ( V _asked ) and a negative supply voltage ( GND ), the device is supplied with electrical energy. In the example of 1 the LED driver ( LEDDRV ) three exemplary LED strands ( LEDS ₁ . LEDS ₂ . LEDS ₃ ) with electrical energy. For this purpose, a first current source of the LED driver ( LEDDRV ) a first electric current ( i ₁ ) with a predetermined first current value in the first node ( k ₁ ) from where this first electric current ( i ₁ ) a first LED string ( LEDS ₁ ) to the negative supply voltage ( GND ) passes through while emits electrical energy. Each of the exemplary LED strands ( LEDS ₁ . LEDS ₂ . LEDS ₃ ) can consist of more or less complex interconnections of several LEDs. In the simplest case, these can be individual LEDs. Here, for example, the parallel connection of two series circuits each consisting of two LEDs to an LED string was chosen as an arbitrary example. A second power source of the LED driver ( LEDDRV ) feeds a second electric current ( i ₂ ) with a predetermined second current value in the second node ( k ₂ ) from where this second electric current ( i ₂ ) a second LED string ( LEDS ₂ ) to the negative supply voltage ( GND ) passes through while emits electrical energy. A third power source of the LED driver ( LEDDRV ) feeds a third electric current ( i ₃ ) with a predetermined third current value into the third node ( k ₃ ) from where this third electric current ( i ₃ ) a third LED string ( LEDS ₃ ) to the negative supply voltage ( GND ) passes through while emits electrical energy.

A first voltage divider consisting of a first resistor ( R ₁ ) and a second resistor ( R ₂ ), captures a first LED string voltage across the first LED string ( LEDS ₁ ), and passes the first voltage level, reduced by the division factor of this first voltage divider, to the LED driver ( LEDDRV ) too. A detection device within the LED driver ( LEDDRV ), for example an analog-to-digital converter, detects this first reduced voltage level. An internal device inside the LED driver ( LEDDRV ) evaluates this reduced first voltage level and concludes on potential defects on the LEDs of the first LED string ( LEDS ₁ ). Of course, this evaluation can also be carried out in whole or in part by the microcomputer ( MCU ) or other devices that can access the values of the analog-to-digital converter.

A second voltage divider consisting of a third resistor ( R ₃ ) and a fourth resistor ( R ₄ ) detects a second LED string voltage that is applied across the second LED string ( LEDS ₂ ), and passes the second voltage level, reduced by the division factor of this second voltage divider, to the LED driver ( LEDDRV ) too. Said detection device within the LED driver ( LEDDRV ), for example the said analog-to-digital converter, detects this second reduced voltage level. The said internal device within the LED driver ( LEDDRV ) evaluates this reduced second voltage level and concludes on potential defects on the LEDs of the second LED string ( LEDS ₂ ). Of course, this evaluation can also be partly or completely carried out by the microcomputer ( MCU ) or other devices that can access the values of the analog-to-digital converter.

A third voltage divider consisting of a fifth resistor ( R ₅ ) and a sixth resistor ( R ₆ ) captures a third LED string voltage across the third LED string ( LEDS ₃ ), and passes the third voltage level, reduced by the division factor of this third voltage divider, to the LED driver ( LEDDRV ) too. Said detection device within the LED driver ( LEDDRV ), for example the said analog-to-digital converter, detects this third reduced voltage level. The said internal device within the LED driver ( LEDDRV ) evaluates this reduced third voltage level and concludes on potential defects on the LEDs of the third LED line ( LEDS ₃ ). Of course, this evaluation can also be partly or completely carried out by the microcomputer ( MCU ) or other devices that can access the values of the analog-to-digital converter. A reference resistor ( R _ref ) supplies the LED driver ( LEDDRV ) with a reference current ( i ref ) of whose value the first current value of the first electric current ( i ₁ ) and the second current value of the second electric current ( i ₂ ) and the third current value of the third electric current ( i ₃ ) depend.

In the example of 1 are all components on a common circuit carrier ( PCB ) housed.

The reference current ( i ref ) caused in the construction of the 1 a constant quiescent current (eg 500μA in the solution of Texas Instruments). The current value of this reference current ( i ref ) requires a compromise in ruggedness in external noise and power consumption. With regard to the energy consumption, a reference current value of the reference current ( i ref ) of OA desirable. With regard to the robustness against external disturbances, the largest possible reference current value of the reference current ( i ref ) desirable. External disturbances have a direct effect on the LED current ( i ₁ . i ₂ . i ₃ ) and can cause a flickering of the light emission of the LED strands ( LEDS ₁ . LEDS ₂ . LEDS ₃ ).

FIG. 2

The 2 shows an exemplary device with three circuit carriers ( PCB ₁ . PCB ₂ . PCB ₃ ). The first circuit carrier ( PCB ₁ ) exemplifies the voltage source ( V _sup ), the microcomputer ( MCU ), the LED driver ( LEDDRV ), the first voltage divider ( R ₁ . R ₂ ), the second voltage divider ( R ₃ . R ₄ ), the third voltage divider ( R ₅ . R ₆ ) and the first LED string ( LEDS ₁ ). The second circuit carrier ( PCB ₂ ) carries only the second LED string ( LEDS ₂ ). The third circuit carrier ( PCB ₃ ) carries only the third LED strand ( LEDS ₃ ). Such a configuration is often found, for example, in backlight modules in vehicles. This creates the problem that then in the fabrication can be ensured only with great effort that the LEDs ( D ₁ . D ₂ . D ₃ . D ₄ ) of the first LED string ( LEDS ₁ ) same parameters as the LEDs ( D ₅ . D ₆ . D ₇ . D ₈ ) of the second LED bar ( LEDS ₂ ) and how the LEDs ( D ₉ . D ₁₀ . D ₁₁ . D ₁₂ ) of the third LED bar ( LEDS ₃ ) exhibit. These parameters are preferably the color temperature and the respective diode kink voltages ( U _k ), where the respective LEDs ( D ₁ to D ₁₂ ) start each individually. In the production of a single circuit substrate this is possible with even tolerable effort. In a configuration of 2 this becomes a logistical problem.

On the other hand, when using an additional NTC for temperature compensation / derating, external wiring with multiple resistors is required. This affects all LEDs simultaneously, even if multiple light functions are controlled in multi-channel drivers.

Often an individual setting of the respective channel current, here the first electric current ( i ₁ ) and / or the second electric current ( i ₂ ) and / or the third electric current ( i ₃ ), desired. This is typically accomplished in the art by a digital, individual configuration to avoid a large number of external resistors.

For this purpose, solutions for temperature compensation are known from the prior art, which rely on more complex resistor networks as reference resistors, these resistance networks can then include temperature-dependent resistors, the temperature dependence of the light emission of the LED strands ( LEDS ₁ . LEDS ₂ . LEDS ₃ ) compensate. Possibly. Several reference resistors are also provided in order to use polynomial approximation to simulate the behavior of the LED driver ( LEDDRV ) even better the temperature behavior of the individual LED strands ( LEDS ₁ . LEDS ₂ . LEDS ₃ ) to adapt.

3 shows such a complex temperature compensation. The resistor network comprises four conventional resistors ( R ₇ . R ₈ . R ₉ . R ₁₀ ) and a temperature-dependent resistor ( R ₁₁ ). For example, it may be provided that the seventh resistor ( R ₇ ) the first reference current ( i _ref1 ), from which then the first electric current ( i ₁ ) for supplying the first LED string ( LEDS ₁ ) and that the eighth resistor ( R ₈ ) the second reference current ( i _ref2 ), from which then the second electric current ( i ₂ ) for supplying the second LED string ( LEDS ₂ ), and that the ninth resistance ( R ₉ ) the third reference current ( i _ref3 ), from then on again the third electric current ( i ₃ ) for supplying the third LED string ( LEDS ₃ ) depends.

In devices such as those of 2 , with several circuit carriers ( PCB ₁ . PCB ₂ . PCB ₃ ) are LED strands ( LEDS ₂ . LEDS ₃ ) from the main circuit carrier ( PCB ₁ ) offset further circuit carriers ( PCB ₂ . PCB ₃ ), so not on the same circuit carrier ( PCB ₁ ) with the LED driver ( LEDDRV ). Since the circuit carriers ( PCB ₁ . PCB ₂ . PCB ₃ ) are manufactured in many factories in different production facilities, is highly likely at the time of the digital power configuration of the main circuit carrier ( PCB ₁ ) in the band end test the so-called binning class of the LEDs of the LED strings ( LEDS ₂ . LEDS ₃ ) on the remote circuit boards ( PCB ₂ . PCB ₃ ) not yet known. The binning class represents, for example, the number of a value interval for the buckling voltage of the LEDs of the respective circuit carrier. On a circuit carrier typically LEDs with a kink voltage ( U _K ) are installed in the same kink tension interval, so that they radiate with approximately the same brightness. The buckling voltage intervals are selected consecutively and preferably not overlapping and, for example, consecutively numbered, the number thus determined being the number of the binning class.

Object of the invention

The invention is therefore based on the object to provide a solution which does not have the above disadvantages of the prior art and has further advantages.

In devices according to the 2 is the individual digital programming and the correct binning coding by means of binning resistors ( R ₇ . R ₈ . R ₉ in 3 ) corresponding 3 due to the time of manufacture of the main circuit carrier ( PCB ₁ ) unknown binning class of LED strands ( LEDS ₂ . LEDS ₃ ) on the further circuit carriers ( PCB ₂ . PCB ₃ ) not solvable.

This object is achieved by a device according to claim ... and a method according to claim ....

Solution of the object according to the invention (only with single application)

In a [generic term] of the type described above, the object is now achieved in that [characterizing part of the main claim] [Note: never use the word according to the invention in descriptions that are to be used for different sets of claims.]

The proposed solution will be described by way of example 4 discussed. It is proposed to use reference resistors ( R ₁₂ . R ₁₃ . R ₁₄ ), matching the LED binning LED binning ( LEDS ₁ . LEDS ₂ . LEDS ₃ ) on the respective circuit carriers ( PCB ₁ . PCB ₂ . PCB ₃ ) as stepped binning resistors ( R ₁₂ . R ₁₃ . R ₁₄ ) and preferably by means of the LED driver ( LEDDRV ).

There remains the problem that the query of the respective remote binning resistor ( R ₁₂ . R ₁₃ . R ₁₄ ) is very susceptible to failure by means of a low reference current less than 1 mA via an external cable wiring.

For this purpose, it is proposed that the settled binning resistors ( R ₁₂ . R ₁₃ . R ₁₄ ) not permanently with a respective reference current ( i _ref1 . i _ref2 . i _ref3 ), but only for a short time. As a result, the total power consumption is lowered and the short-term current level of the respective reference current ( i _ref1 . i _ref2 . i _ref3 ) can be raised massively, so that the signal to noise ratio is raised massively and a flicker is avoided.

This can be done by a digital control within the LED driver ( LEDDRV ) the respective reference current ( i _ref1 . i _ref2 . i _ref3 ), the respective binning resistance ( R ₁₂ . R ₁₃ . R ₁₄ ), generates a short high current pulse, and for robust resistance evaluation by a device within the LED driver ( LEDDRV ) or in cooperation with the microcomputer ( MCU ) be used. Further digital filtering further reduces the risk of current variation due to external noise.

In the LED driver ( LEDDRV ) is a typically already existing current sink, so for example, a non-wired LED driver output ( k ₄ . k ₅ . k ₆ ) per circuit carrier ( PCB ₁ . PCB ₂ . PCB ₃ ) is used to connect an external binning resistor ( R ₁₂ . R ₁₃ . R ₁₄ ) to energize. Using the integrated diagnostics function (ADC measurement) of the LED driver output ( k ₄ . k ₅ . k ₆ ), which is now used to measure the binning resistances ( R ₁₂ . R ₁₃ . R ₁₄ ) is binned or temperature information can be formed across multiple digital thresholds that corrects the current of a configurable number of LED drivers. For this purpose, the diagnostic inputs ( d ₄ . d ₅ . d ₆ ) of the corresponding LED driver outputs ( k ₄ . k ₅ . k ₆ ) with the corresponding LED driver outputs ( k ₄ . k ₅ . k ₆ ) connected with voltage parts.

With the stepped binning resistors ( R ₁₃ . R ₁₄ . R ₁₅ ) on the remote circuit boards ( PCB ₂ . PCB ₃ ), the respective binning class of the LEDs of the LED strings ( LEDS ₂ . LEDS ₃ ) on the remote circuit boards ( PCB ₂ . PCB ₃ ) coded. By a respective brief energization of the respective stepped binning resistors ( R ₁₃ . R ₁₄ . R ₁₅ ) with current-equivalent reference currents ( i _ref1 . i _ref2 . i _ref3 ) occurs at the remote binning resistors ( R ₁₃ . R ₁₄ . R ₁₅ ) a respective binning voltage ( V _bin1 . V _bin2 . V _bin3 ) at the respective diagnostic input ( d ₄ . d ₅ . d ₆ ), which corresponds to the respective driver output ( k ₄ . k ₅ . k ₆ ), for example by an analog-to-digital converter within the LED driver ( LEDDRV ) and the LED driver ( LEDDRV ) on the main circuit carrier ( PCB ₁ ) or the microcomputer ( MCU ), which can also evaluate these recorded voltage values, the binning class of the relevant LED string ( LEDS ₂ . LEDS ₃ ) of the relevant remote circuit carrier ( PCB ₂ . PCB ₃ ) signals.

5 shows a possible assignment of the streams to binning classes.

After measuring the binning voltages ( V _bin1 . V _bin2 . V _bin3 ) at the respective diagnostic inputs ( d ₄ . d ₅ . d ₆ ), the binning values thus acquired can be temporarily stored. The power sources on the wired LED driver outputs ( k ₁ . k ₂ . k ₃ ) are then calculated according to the detected binning voltages ( V _bin1 . V _bin2 . V _bin3 ) are set relative to one another by corresponding switching of internal references. Preferably, each current source is within the LED driver, thus also a programmable digital-to-analog converter whose output current is in a programmable ratio to a base reference current. Particularly preferred is this base reference current, the first reference current ( i _ref ), which has a reference resistor ( R _ref ) on the main circuit carrier ( PCB ₁ ) flows through.

This reference current ( i _ref ) can also be queried pulsed, if this internally within the LED driver ( LEDDRV ) is converted into a reference voltage and this in a sample-and-hold circuit (eg: https://de.wikipedia.org/wiki/Sample-and-Hold-Schaltung) in the times in which the reference resistance ( R _ref ) is not energized, is stored. The reference current can be selected higher and therefore more robust. The quiescent current drops on average. For example, the reference current may be supplied to the output node at a 1% duty cycle of the PWM frequency of the LED current sources (FIG. k ₁ . k ₂ . k ₃ ).

If not only the binning class of the LED string ( LEDS ₁ . LEDS ₂ . LEDS ₃ ) of a circuit carrier ( PCB ₁ . PCB ₂ . PCB ₃ ), but also the temperature of this circuit carrier, ( PCB ₁ . PCB ₂ . PCB ₃ ), additional LED driver outputs for the measurement of a temperature-dependent resistor can additionally be used as a second measuring channel per circuit carrier ( PCB ₁ . PCB ₂ . PCB ₃ ). It is also conceivable to connect a temperature-dependent resistor in series with a Binnig resistor. In that case, over the temperature range, the resistance of the temperature measuring resistor must not fluctuate more than the step height for the binning resistors between the individual binning classes. As a temperature-dependent resistor, for example, NTC resistors come into question.

It is thus a method for detecting and using the LED Binnings a remote circuit substrate ( PCB ₂ . PCB ₃ ) proposed. At least temporarily, a current source output ( k ₅ . k ₆ ) of an LED driver ( LEDDRV ), which is suitable and intended for driving a connectable LED string, for supplying a binning resistor ( R ₁₃ . R ₁₄ ) located on the remote circuit board ( PCB ₂ . PCB ₃ ), not used as intended. The LED driver ( LEDDRV ) is located on a main circuit carrier ( PCB ₁ ). The main circuit carrier ( PCB ₁ ) and the remote circuit carrier ( PCB ₂ . PCB ₃ ) are mechanically offset from each other, but interconnected by the electrical wires.

The power source output ( k ₅ . k ₆ ) of the LED driver ( LEDDRV ), which is suitable and intended for driving a connectable LED string, can be assigned a voltage measuring device which is provided and suitable for monitoring the LED function of the respective, connectable LED string. This connectable LED string is just not on the remote circuit board ( PCB ₂ . PCB ₃ ) but by the respective binning resistor ( R ₁₃ . R ₁₄ ) has been replaced for other purposes. This allows the LED driver ( LEDDRV ) the determination of a value of the voltage drop in the form of a value of the binning voltage ( V _bin2 . V _bin3 ) over the binning resistor ( R ₁₃ . R ₁₄ ) by means of the voltage measuring device during energization of the binning resistor ( R ₁₃ . R ₁₄ ) through the relevant power source. Preferably, the LED driver and / or the microcomputer ( MCU ) this value, which is measured by the voltage measuring device during the energization of the binning resistor ( R ₁₃ . R ₁₄ ) was determined, at least in the times in which said energization does not take place. The LED driver provides an electrical current ( i ₂ . i ₃ ) for supplying a respective LED string ( LEDS ₂ . LEDS ₃ ) by means of a further current source output ( k ₂ . k ₃ ) of the LED driver ( LEDDRV ) connected to the relevant LED string ( LEDS ₂ . LEDS ₃ ), depending on the determined value of the voltage drop across the binning resistor ( R ₁₃ . R ₁₄ ) one. The relevant LED string ( LEDS ₂ . LEDS ₃ ) is located on the remote circuit carrier ( PCB ₂ . PCB ₃ ) and is with the relevant parent node ( k ₂ . k ₃ ) of the corresponding power source of the LED driver ( LEDDRV ) connected.

Preferably, the energization of the binning resistor ( R13 . R14 ) pulsed.

In a more detailed form of the proposal, the electric current ( i2 . i3 ) for the supply of the relevant LED string ( LEDs2 . LEDS3 ) pulse modulated and / or pulse width modulated. This modulation of the electric current ( i2 . i3 ) for the supply of the relevant LED string ( LEDs2 . LEDS3 ) preferably has a PWM frequency and a duty cycle. The energization of the binning resistor ( R13 . R14 ) is performed with a duty cycle of less than 50% or better less than 25% or better less than 10% or better less than 5% or better less than 2% or better less than 1% with PWM frequency. This reduces the quiescent current consumption according to the decrease in the duty cycle. It is also advantageous that the pulse frequency for the energization of the binning resistor ( R13 . R14 ) of the PWM frequency for the energization of the LED string ( LEDS ₂ . LEDS ₃ ) divided by a whole positive number greater than zero. This then leads to a further decrease in the quiescent power requirement.

In order to determine the temperature of the remote circuit substrate, it makes sense to replace the binning resistor by a series circuit, which is formed by a first resistor and a second resistor. In this case, either the temperature coefficient of the first resistor is preferably greater than that of the second resistor or, alternatively, the temperature coefficient of the first resistor is negative and that of the second resistor is positive.

Advantage of the invention

In addition to the channel-specific digital power configuration, some of the LED channels may be individually binned or temperature-current corrected for LEDs on remote circuit boards.

The method allows a robust query and can reduce the quiescent current of the application compared to the prior art due to the reduced duty cycle of the query current.

Furthermore, digital filtering (e.g., median formation) can increase the robustness of noise.

The invention enables flexible binning or temperature correction in LED lighting. Current systems either use only digital current setting or an external reference resistor with low reference current which is susceptible to interference. The solution offers the optional use of external reference or temperature resistance on remote circuit boards without additional internal effort, since the existing components (current sources, analogue to digital converters) are used.

The advantages are not limited to this.

LIST OF REFERENCE NUMBERS

d ₁

first diagnostic input for the first output node ( k ₁ ) of the LED driver ( LEDDRV );

d ₂

second diagnostic input for the second output node ( k ₂ ) of the LED driver ( LEDDRV );

d ₃

third diagnostic input for the third output node ( k ₃ ) of the LED driver ( LEDDRV );

d ₄

fourth diagnostic input for the fourth output node ( k ₄ ) of the LED driver ( LEDDRV );

d ₅

fifth diagnostic input for the fifth output node ( k ₅ ) of the LED driver ( LEDDRV );

d ₆

sixth diagnostic input for the sixth output node ( k ₆ ) of the LED driver ( LEDDRV );

D ₁

first LED in the first LED string of the first LED string ( LEDS ₁ );

D ₂

second LED in the first LED string of the first LED string ( LEDS ₁ );

D ₃

third LED in the second LED chain of the first LED string ( LEDS ₁ );

D ₄

fourth LED in the second LED chain of the first LED string ( LEDS ₁ );

D ₅

fifth LED in the third LED string of the second LED string ( LEDS ₂ );

D ₆

sixth LED in the third LED string of the second LED string ( LEDS ₂ );

D ₇

seventh LED in the fourth LED string of the second LED string ( LEDS ₂ );

D ₈

eighth LED in the fourth LED string of the second LED string ( LEDS ₂ );

D ₉

ninth LED in the fifth LED chain of the third LED string ( LEDS ₃ );

D ₁₀

tenth LED in the fifth LED chain of the third LED string ( LEDS ₃ );

D ₁₁

eleventh LED in the sixth LED string of the third LED string ( LEDS ₃ );

D ₁₂

twelfth LED in the sixth LED string of the third LED string ( LEDS ₃ );

DB

Data bus between exemplary microcomputer ( MCU ) and LED driver ( LEDDRV );

GND

negative supply voltage line;

i ₁

first electric current;

i ₂

second electric current;

i ₃

third electric current;

i ref

Reference current;

i _ref1

first reference current;

i _ref2

second reference current;

i _ref3

third reference current;

k ₁

first output node of the LED driver ( LEDDRV ) via which the LED driver ( LEDDRV ) the exemplary first LED string ( LEDS ₁ ) supplied by a power source with electrical energy.

k ₂

second output node of the LED driver ( LEDDRV ) via which the LED driver ( LEDDRV ) the exemplary second LED string ( LEDS ₂ ) supplied by a power source with electrical energy.

k ₃

third output node of the LED driver ( LEDDRV ) via which the LED driver ( LEDDRV ) the exemplary third LED string ( LEDS ₃ ) supplied by a power source with electrical energy.

k ₄

fourth output node of the LED driver ( LEDDRV ) via which the LED driver ( LEDDRV ) an exemplary fourth LED string ( LEDS ₄ ) can supply by means of a power source with electrical energy.

k ₅

fifth output node of the LED driver ( LEDDRV ) via which the LED driver ( LEDDRV ) an exemplary fifth LED string ( LEDS ₅ ) can supply by means of a power source with electrical energy.

k ₆

sixth output node of the LED driver ( LEDDRV ) via which the LED driver ( LEDDRV ) an exemplary sixth LED string ( LEDS ₆ ) can supply by means of a power source with electrical energy.

LEDDRV

LED driver device also referred to as LED driver for short;

LEDS ₁

first LED string;

LEDS ₂

second LED string;

LEDS ₃

third LED string;

LEDS ₄

fourth LED string;

LEDS ₅

fifth LED string;

LEDS ₆

sixth LED string;

MCU

Microcomputer. The microcomputer controls the LED driver ( LEDDRV ) via the data bus ( DB );

PCB

Circuit boards;

PCB ₁

first circuit carrier;

PCB ₂

second circuit carrier;

PCB ₃

third circuit carrier;

r ₁

first reference input for the first reference current ( i _ref1 );

r ₂

second reference input for the second reference current ( i _ref2 );

r ₃

third reference input for the third reference current ( i _ref3 );

R ₁

first resistor in the first voltage divider;

R ₂

second resistor in the first voltage divider;

R ₃

third resistor in the second voltage divider;

R ₄

fourth resistor in the second voltage divider;

R ₅

fifth resistor in the third voltage divider;

R ₆

sixth resistor in the third voltage divider;

R _ref

Reference resistor;

SdT

State of the art;

V ₀

Operating voltage. The operating voltage is the output voltage of the operating voltage source ( V _sup );

V _asked

Supply voltage line;

V _sup

Operating voltage source. The operating voltage source supplies the operating voltage ( V ₀ );

Claims (3)

Device - with a main circuit carrier (PCB1) and - with a remote circuit carrier (PCB ₂ , PCB ₃ ) and - with a binning resistor (R ₁₃ , R ₁₄ ) and - with a connectable LED string and - with a voltage measuring device and - with a LED driver (LEDDRV) and - possibly with a microcomputer (MCU) and - wherein the LED driver (LEDDRV) has a current source output (k ₅ , k ₆ ) and - wherein the current source output (k ₅ , k ₆ ) the LED driver (LEDDRV) is suitable and provided for driving the connectable LED string which is located on a main circuit carrier (PCB ₁ ), and - wherein the main circuit carrier (PCB ₁ ) and the remote circuit carrier (PCB ₂ , PCB ₃ ) - The voltage measuring device can be assigned to the current source output (k ₅ , k ₆ ) and - wherein the voltage measuring device for monitoring the LED function of the relevant, connectable LED string provided and - wherein the voltage measuring device is suitable for supplying current to the binning resistor (R ₁₃ , R ₁₄ ), and - wherein the binning resistor (R ₁₃ , R ₁₄ ) is located on the remote circuit carrier (PCB ₂ , PCB ₃ ), and wherein the voltage _{measuring means detects} a value of the voltage drop in the form of a value of the binning voltage (V _bin2 , V _bin3 ) via the binning resistor (R ₁₃ , R ₁₄ ) during the energization, and wherein the LED driver and / or the Microcomputer (MCU) stores this value, which was determined by the voltage measuring device during the energization of the binning resistor (R ₁₃ , R ₁₄ ), at least in times when said energization does not take place, and - wherein the LED driver (LEDDRV ) the average of an electric current (i ₂ , i ₃ ) for supplying a respective LED string (LEDS ₂ , LEDS ₃ ) by means of another current source output (k ₂ , k ₃ ) of the LED driver (LEDDRV), with the relevant LED strand (LEDS ₂ , LEDS ₃ ) is connected as a function of the determined value of the voltage drop across the binning resistor (R ₁₃ , R ₁₄ ) and - whereby the relevant LED string (LEDS 2, LEDS 3) on the remote circuit carrier (PCB 2, PCB3) and - wherein the binning resistor is characterized by - a series circuit consisting of a first resistor and a second resistor is formed, and - wherein the temperature coefficient of the first resistor is greater than that of the second resistor, or - wherein the temperature coefficient of the first resistor is negative and that of the second resistor is positive. Device after Claim 1 - Wherein the energization of the binning resistor (R ₁₃ , R ₁₄ ) is pulsed. Device after Claim 1 and / or 2 - wherein the electrical current (i ₂ , i ₃ ) for the supply of the relevant LED string (LEDS ₂ , LEDS ₃ ) is pulse-modulated and / or pulse-width modulated, and - wherein this modulation of the electric current (i ₂ , i ₃ ) has a PWM frequency and a duty cycle for the supply of the relevant LED string (LEDS ₂ , LEDS ₃ ) and - wherein the energization of the binning resistor (R ₁₃ , R ₁₄ ) with a duty cycle of less than 50 % or less than 25% or less than 10% or less than 5% or less than 2% or less than 1% with PWM frequency.

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