Electronic system for driving a light source and method of driving a light source

Abstract

Embodiments of the present disclosure generally relate to electronic systems for driving light sources and methods of driving light sources. A system includes a lighting device coupled to output power pins, a microcontroller circuit and a driver circuit that receives data therefrom, and a switch coupled in series to the lighting device. The driver circuit includes the output power pins and selectively propagates a power voltage to the output power pins to provide respective pulse width modulated power signals at the output power pins. The driver circuit calculates a duty cycle value of the pulse width modulated power signals in accordance with the data received from the microcontroller circuit. The lighting device includes at least a subset of lighting devices coupled to the same output power pins. The microcontroller individually controls the switch via respective control signals to individually adjust a brightness of the lighting devices in the at least a subset of lighting devices.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Italian patent application No. 102021000007490, filed on March 26, 2021, which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure generally relates to driving light sources, and in certain embodiments, to driving light sources including light-emitting diodes (LEDs). Background Technology

[0004] As is known, LEDs are increasingly being used in lighting devices (e.g., lamps) in a growing number of fields due to their advantageous properties regarding cost, size, duration, directionality, and electrical efficiency.

[0005] LED-based lighting devices can be used independently or included in more complex systems. In the latter case, the controller is typically configured to manage the operation of multiple different loads. For example, in the automotive sector, the switching control of LEDs and their functions are often included in a system. This system may include a microcontroller and at least one driver circuit formed in different chips for controlling various functions, such as mirror adjustment, locking control, direction indicators, and various lighting functions. The driver circuit can be provided, for example, as a dedicated standard product (ASSP).

[0006] Devices available from STMicroelectronics Group companies under the trade names L99DZ100G and L99DZ100GP (as described in datasheet “DS11546Rev5” (March 2019) available at st.com) are examples of such driver circuits configured to control various functions (e.g., area controllers, such as “door modules”) in a specific area of ​​a vehicle, including one or more lighting functions. Similarly, devices available from STMicroelectronics Group companies under the trade name L99DZ120, as described in datasheet “DS11567Rev5” (March 2019) available at st.com, are also examples of driver circuits configured to control various functions (e.g., area controllers, such as “door modules”) in a specific area of ​​a vehicle, including one or more lighting functions.

[0007] Such known devices can perform programmable brightness compensation for light sources they drive, as disclosed, for example, in U.S. Patent US10375774B2 assigned to STMicroelectronics Group Corporation. When an LED element is turned on, it may be desirable to maintain a constant brightness. The brightness of an LED depends on several parameters, including the actual supply voltage level. However, particularly for automotive applications, the supply voltage is typically not constant: at supply voltage V... BAT Many voltage transients can occur, such as the negative and positive voltages caused by starting a vehicle engine, which can affect the power supply voltage V. BAT The brightness of an LED may drop to half its nominal value (e.g., from 12V to 6V) or be affected by the switching on / off of heavy inductive loads (e.g., a window opening motor). Therefore, under varying or unstable power supply voltage conditions, the brightness of an LED may not be constant and flickering may occur, which is an undesirable effect.

[0008] To mitigate the aforementioned problems, document US10375774 B2 discloses an electrical load control system intended for, for example, automotive applications, as appended herein. Figure 1 As shown. The electrical load control system 100 includes a driver circuit 101 and a microcontroller 102. ,n LED group 311 to 31 n (e.g., LED strings), and possibly other loads such as mirror adjustment motors, locking control motors, direction indicators, and other lighting elements (in...). Figure 1 (Not visible in the middle).

[0009] The microcontroller 102 has multiple controller I / O pins 102A coupled to driver circuitry 101 via several corresponding connection lines 105 (e.g., implemented by a serial peripheral interface bus). Driver circuitry 101 includes a brightness control device 20, logic and diagnostic circuitry 106, driver circuitry 29, and optional other driver circuitry (in...). Figure 1 (Not visible in the middle).

[0010] Therefore, the driver circuit 101 has a first plurality of I / O pins 101A coupled to the connection line 105, the logic and diagnostic circuit 106, and the brightness control device 20, and a second plurality of I / O pins coupled to other loads (in Figure 1 (not visible in the middle), and coupled to driver circuit 29 and multiple LED groups 311 to 31 n The third multiple I / O pins 101C1 to 101C n .

[0011] Optionally, current setting or current limiting elements (e.g., resistors) can be coupled in series to each LED group 31.

[0012] Brightness control device 20 includes: processing circuitry 21 (e.g., implemented as a hardwired logic state machine); and a first register circuitry 22 for storing the nominal duty cycle DC of the power supply signal to be applied to each LED group 31. N The values ​​(e.g., n values); the second register circuit 23, used to store the LED forward voltage V for each LED group 31. LED The value (e.g., n values); the third register circuit 24, used to store the compensation duty cycle DC of the power signal to be applied to each LED group 31. C The values ​​(e.g., n values); and the ADC converter 25, for providing (e.g., acquiring) the actual power supply voltage V received from a power source such as a battery. BAT The numerical value V S .

[0013] The processing circuit 21 that implements the algorithm for brightness control can be the same components as the logic and diagnostic circuit 106. The brightness control device 20 operates as described below.

[0014] During the setup phase, for each of the n LED groups 31, the register in the first register circuit 22 is loaded with the nominal duty cycle value DC. N_i Furthermore, for each of the n LED groups 31, the register in the second register circuit 23 is loaded with the LED positive voltage V. LED_i (Depending on the desired lighting function to be achieved, these values ​​are received from the microcontroller 102, for example, via connection line 105).

[0015] Additionally, the register in the second register circuit 23 can be loaded with a (single) activation bit for each LED group 31, the value of which determines whether voltage compensation should be applied to the corresponding duty cycle value. Nominal power supply voltage V TH (For example, equal to 10V) is also stored in the brightness control device 20.

[0016] During operation, in each compensation cycle, initially, the processing circuit 21 reads the digital value V of the actual power supply voltage at the output of the ADC converter 25. S Then, the LED group counter i is initialized to 1. The processing circuit 21 checks whether an adjustment has been set for the specific i-th LED group 31 by reading the contents of the relevant adjustment activation bit in the corresponding register in the second register circuit 23.

[0017] If affirmative, read the value for the corresponding LED group 31. i The nominal duty cycle DC in the first register circuit 22 and the second register circuit 23 N_i and LED forward voltage V LED_iAnd the current compensation duty cycle DC for the i-th LED group is calculated in processing circuit 21 using the following equation. C_i And then store it in the corresponding register of the third register circuit 24:

[0018]

[0019] If no adjustment is set for the specific i-th LED group 31, the current duty cycle DC C_i Set to nominal duty cycle DC N_i .

[0020] Then, in both cases, the LED group counter i is incremented, and it is verified whether the current duty cycle DC has been determined for each LED group 31. C_i .

[0021] If the result is negative, the processing circuit 21 checks whether an adjustment has been set for the subsequent LED group 31; if the result is positive, the processing circuit 21 prepares to start a new compensation cycle.

[0022] The current (compensated) duty cycle DC is loaded into the register of the third register circuit 24. C_i The value is then used for driving elements (e.g., high-side driver transistors HS) 301 to 30 n To drive LED group 31, driver elements 301 to 30 n The corresponding duty cycle value DC read from the third register circuit 24 will be used. C_i Modulated power supply voltage V BAT Propagate to the corresponding I / O pins 101C1 to 101C n (For example, using pulse width modulation, PWM), and thus providing a corresponding PWM power supply signal V. BAT,1 To V BAT,n .

[0023] Due to the increasing complexity of LED lighting systems (especially in automotive applications), the number of LED groups 31 driven by system 100 can be greater than the number n of I / O pins 101C of driver circuit 101 (typically, the number n of I / O pins 101C is equal to the number of registers in each of the first register circuit 22, the second register circuit 23, and the third register circuit 24, and equal to the number of driver elements 30 provided in driver circuit 29). In this case, multiple LED groups 31 can be coupled in parallel to the same I / O pins 101C of driver circuit 101, such as... Figure 2 As shown.

[0024] For example, m LED groups 31 1,1 31 1,2... 31 1,m They can be coupled in parallel to the same I / O pin 101C1 so that they can be controlled by the same driver element 301 and receive the same PWM power supply signal V. BAT,1 .

[0025] This can also be applied to other I / O pins 101C, such as a certain number of LED groups 31 coupled in parallel to each I / O pin 101C, possibly with different numbers of LED groups coupled in parallel to each I / O pin 101C.

[0026] In such Figure 2 In the control system shown, all LED groups 31 coupled in parallel to the same I / O pin 101C are driven by the same driver element 30, and therefore according to the same duty cycle value programmed by the microcontroller 102 via (e.g., SPI) connection line 105 (possibly compensating for the power supply voltage V as described above). BAT The LEDs are driven by changes in their brightness. Therefore, all LED groups arranged in parallel and coupled to the same I / O pin 101C exhibit the same brightness. The control system does not allow individual control of each LED group 31 (e.g., controlling LED group 31 individually). 1,1 Up to 31 1,m (brightness).

[0027] Therefore, there is a need in the art for an improved control system for lighting loads (e.g., LED groups) that facilitates the individual control of multiple lighting loads while maintaining the possibility of compensating for duty cycles in a centralized manner in response to changes in power supply voltage. Summary of the Invention

[0028] The purpose of one or more embodiments is to provide an improved control system for lighting loads. One or more embodiments may relate to a method of driving lighting equipment.

[0029] In one or more embodiments, the system may include microcontroller circuitry and driver circuitry coupled to the microcontroller circuitry to receive data therefrom. The driver circuitry may include a plurality of output power supply pins and may be configured to selectively propagate power supply voltages to the output power supply pins to provide corresponding pulse-width modulated power signals at the output power supply pins.

[0030] The driver circuit can be configured to calculate the corresponding duty cycle value of the pulse width modulated power signal based on the data received from the microcontroller circuit.

[0031] The system may also include multiple lighting devices coupled to multiple output power pins. The multiple lighting devices may include at least a subset of lighting devices coupled to the same output power pin among the multiple output power pins.

[0032] The system may also include a set of corresponding electronic switches for lighting devices that are coupled in series to at least one subset of the lighting devices.

[0033] The microcontroller circuit can be configured to individually control electronic switches via corresponding control signals to individually adjust the brightness of at least one subset of the lighting devices.

[0034] Therefore, one or more embodiments can help to individually control the brightness of multiple lighting loads supplied by the same pulse width modulated power signal. Attached Figure Description

[0035] To gain a more complete understanding of this disclosure and its advantages, reference is now made to the following description in conjunction with the accompanying drawings.

[0036] Figure 1 This is a block diagram of a control system for lighting loads;

[0037] Figure 2 This is a block diagram of another control system used for lighting loads;

[0038] Figure 3 This is a block diagram of a control system for an embodiment of a lighting load;

[0039] Figure 4 This is a block diagram of a control system for an embodiment of a lighting load;

[0040] Figure 5 This is a flowchart illustrating an embodiment of a diagnostic process implemented in a control system for lighting loads; and

[0041] Figure 6 This is a flowchart of an embodiment of an overcurrent event management procedure implemented in a control system for lighting loads. Detailed Implementation

[0042] This invention provides numerous applicable inventive concepts that can be implemented in a variety of specific environments. Specific embodiments are merely illustrative of particular configurations and do not limit the scope of the claimed embodiments. Unless otherwise stated, features from different embodiments can be combined to form other embodiments.

[0043] Variations or modifications described in one embodiment may also be applied to other embodiments. Furthermore, it should be understood that various changes, substitutions, and alterations may be made herein without departing from the spirit and scope of this disclosure as defined by the appended claims.

[0044] In the following description, one or more specific details are shown to provide a thorough understanding of examples of embodiments described herein. Embodiments may be obtained without one or more specific details or by utilizing other methods, components, materials, etc. In other instances, known structures, materials, or operations have not been shown or described in detail so that certain aspects of the embodiments are not obscured.

[0045] References to "embodiment" or "one embodiment" within the framework of this specification are intended to indicate that a particular configuration, structure, or feature described with respect to that embodiment is included in at least one embodiment. Therefore, phrases such as "in an embodiment" or "in one embodiment" that may appear at one or more points in this specification do not necessarily refer to the same embodiment. Furthermore, in one or more embodiments, particular constructions, structures, or features may be combined in any suitable manner.

[0046] The titles / references used herein are provided for convenience only and therefore do not limit the scope or range of protection of the embodiments.

[0047] In all the accompanying drawings, unless the context otherwise indicates, the same parts or elements are indicated by the same reference numerals / numbers, and for the sake of brevity, the corresponding descriptions will not be repeated.

[0048] One or more embodiments may relate to an improved control system for lighting loads (e.g., groups of LEDs) that facilitates individual control of multiple lighting loads while retaining the possibility of compensating for duty cycles in a centralized manner in response to variations in power supply voltage.

[0049] Refer again Figure 1 and Figure 2 It has been noted that if the number of lighting devices (e.g., LED groups 31) to be driven by controller device 101 is greater than the number n of I / O pins 101C of controller device (also referred to in this specification as the number of “channels” of controller device), then multiple lighting devices (e.g., 31) 1,1 Up to 31 1,m They can be coupled in parallel to the same I / O pin 101C, but the disadvantage is that the possibility of individually controlling each lighting device 31 is lost, for example, individually controlling its brightness.

[0050] A first direct solution to this problem would require adapting the driver circuitry 101 by increasing the number of available I / O pins 101C. However, this solution would require a complete redesign of the driver circuitry 101. This would increase costs, as increasing the number of channels would also require increasing the number of registers in the first register circuitry 22, the second register circuitry 23, and the third register circuitry 24, and increasing the number of driver elements 30. Furthermore, this solution could be impractical, as the number of I / O pins in the driver circuitry 101 can be largely limited by the size or type of the integrated circuit 101's package (e.g., an LQFP-64 package).

[0051] Therefore, as Figure 3 One or more embodiments illustrated herein may rely on different methods, wherein the microcontroller 102 is configured to connect to each lighting device (e.g., LED group 31) that is coupled in parallel to the same I / O pin (e.g., 101C1). 1,1 Up to 31 1,m Provide the corresponding duty cycle control signal (e.g., signal P) 1,1 To P1 ,m ).

[0052] Duty cycle control signal P 1,1 To P1 ,m It can be generated by the microcontroller 102 based on software programmed in the microcontroller itself.

[0053] For example, the duty cycle control signal P 1,1 To P1 ,m It can be a pulse width modulation (PWM) signal, which has a frequency higher than that specified by the driver circuit 101 at I / O pins 101C1 to 101C2. n The PWM power signal V provided at the location BAT,1 To V BAT,n The frequency.

[0054] As a non-limiting example only, the duty cycle controls the PWM signal P 1,1 To P1 ,m The frequency can be 10 to 20 times the frequency of the PWM power signal provided at I / O pin 101C. For example, the PWM power signal V BAT,1 To V BAT,n The frequency can be in the range of 100Hz to 1kHz, and the duty cycle controls the PWM signal P. 1,1 To P1 ,m The frequency can be in the range of 2kHz to 10kHz.

[0055] Therefore, in such Figure 3In one or more embodiments of the lighting load control system 100' shown, the driver circuit 101 may include a plurality of I / O pins 101C1 to 101C n It provides the corresponding PWM power signal V BAT,1 To V BAT,n Its duty cycle can be controlled by a brightness control device 20 based on the power supply voltage V. BAT To compensate for changes in brightness, several lighting loads (LED groups) can be connected in parallel to each I / O pin 101C. Additionally, the microcontroller 102 can output corresponding independent brightness setting signals (or duty cycle control PWM signals) P. 1,1 To P1 ,m Supply to the same PWM power signal V BAT,1 Each lighting load provided.

[0056] In one or more embodiments, each brightness setting signal P 1,1 To P1 ,m Can be via Figure 4 The additional circuitry illustrated in the diagram propagates to the corresponding LED group 31. 1,1 Up to 31 1,m , Figure 4 yes Figure 3 Examples of some implementation details of the control system 100' illustrated herein.

[0057] For the sake of simplicity and ease of explanation, Figure 4 Only one I / O pin 101C1 of the driver circuit 101 is shown, and only the two LED groups 31 coupled to it are shown. 1,1 and 31 1,m However, those skilled in the art will understand that a similar circuit arrangement can be provided at any LED group 31, which is coupled in parallel to another LED group and configured to receive a corresponding individual brightness setting signal P.

[0058] In addition, Figure 4 In this document, only some components of the driver circuit 101 are shown for the sake of illustration.

[0059] like Figure 4 As illustrated, multiple discrete components can be used to propagate (e.g., superimpose) the brightness setting signal P to the corresponding LED group 31 to set its individual duty cycle.

[0060] For example, LED group 31 coupled to I / O pin 101C1 1,1 The brightness setting circuit device may include: input pin 40 1,1 Configured to receive brightness setting signal P 1,1The first current path between I / O pin 101C1 and ground includes a first resistor R1. 1,1 Second resistor R2 1,1 and the first transistor T1 1,1 The series arrangement, the first transistor T1 1,1 The current path is coupled to the second resistor R2 1,1 A second current path between I / O pin 101C1 and ground; the second current path includes the second transistor T2. 1,1 Third resistor R3 1,1 and one or more LED31 1,1 A series arrangement of one or more LEDs 31 1,1 Series coupled to the third resistor R3 1,1 Between and the earth.

[0061] like Figure 4 As illustrated, input pin 40 1,1 It can be coupled to the first transistor T1 1,1 The control terminal to transmit the brightness setting PWM signal P 1,1 For example, the circuit may include a connection to input pin 40. 1,1 With the first transistor T1 1,1 The fourth resistor R4 between the control terminals 1,1 and coupled to the first transistor T1 1,1 The fifth resistor R5 between the control terminal and ground 1,1 .

[0062] like Figure 4 As shown, the second transistor T2 1,1 The control terminal can be coupled to the first resistor R1 1,1 With the second resistor R2 1,1 The middle node.

[0063] like Figure 4 As shown, the first transistor T1 1,1 It can be an npn type BJT transistor, which has a 40° coupling to the input pin. 1,1 The base terminal is coupled to the second resistor R2. 1,1 The collector terminal and the emitter terminal coupled to ground. However, those skilled in the art will understand that alternative embodiments may instead include, for example, an n-channel type MOS transistor having a collector terminal coupled to the input pin 40. 1,1 The gate terminal is coupled to the second resistor R2. 1,1 The drain extremum and the source extremum coupled to ground.

[0064] like Figure 4 As shown, the second transistor T21,1 It can be a PNP type BJT transistor, which has a coupling to the first resistor R1. 1,1 With the second resistor R2 1,1 The base terminal of the middle node is coupled to the third resistor R3. 1,1 The collector terminal and the emitter terminal coupled to I / O pin 101C1. However, those skilled in the art will understand that alternative embodiments may alternatively include, for example, a p-channel type MOS transistor having a first resistor R1 coupled to it. 1,1 At the second resistor R2 1,1 The gate terminal of the intermediate node is coupled to the third resistor R3. 1,1 The drain terminal and the source terminal coupled to I / O pin 101C1.

[0065] Those skilled in the art will understand that Figure 4 The circuit arrangement shown is merely an example of a possible arrangement that allows for further modulation at a higher frequency of the PWM power signal received from I / O pin 101C at LED group 31.

[0066] Normally, when the PWM power supply signal received from a certain I / O pin 101C is low, the corresponding LED group 31 is not supplied with current and is therefore turned off (independent of the value of the brightness setting signal P).

[0067] When a PWM power supply signal received from a certain I / O pin 101C is high, current can be supplied to the corresponding LED group 31 (i.e., it is turned on). However, the value of the corresponding brightness setting signal P will determine whether the corresponding LED group is actually turned on. For example, if P is high, transistor T1 will turn on, which will cause transistor T2 to turn on, and thus the corresponding LED group 31 will be turned on.

[0068] Conversely, if P is low, transistor T1 will not conduct, causing transistor T2 to not conduct, and thus turning off the corresponding LED group 31. Since the frequency of the brightness setting signal P is higher than the frequency of the PWM power signal received from I / O pin 101C, the corresponding LED group 31 can be turned off by the PWM power signal V. BAT,1 It turns on and off several times during a single "on" period, thereby adjusting its brightness.

[0069] Therefore, those skilled in the art will understand that one or more embodiments may typically include multiple LED groups 31 coupled in parallel to the same I / O pin 101C1 of the driver circuit 101. 1,1 By 31 1,mAnd an electronic switch series coupled to each LED group, which allows selective coupling of the LED group to and decoupling from the I / O power pin 101C based on the corresponding brightness setting signal P received from the microcontroller 102.

[0070] In one or more embodiments, the logic of the driver circuit 101 and the diagnostic circuit 106 may be additionally configured to perform diagnostic procedures, for example, as a state machine running in the diagnostic circuit. Considering two PWM signals (at high and low frequencies) applied to the lighting load, the diagnostic process can detect faults (e.g., unexpected short-circuit conditions or overcurrents) in the lighting load that are coupled in parallel to the same I / O pin 101C and provided by the same output.

[0071] It should be noted that due to parasitic capacitance on the printed circuit board, a current peak is typically delivered by the driver element 30 when the lighting load 31 is turned on. In one or more embodiments, a diagnostic procedure can distinguish such recurring current peaks from current peaks caused by a short circuit to ground in a branch or pin 101C. Therefore, the diagnostic procedure can help protect the driver circuit 101 and may report detected faults to the microcontroller 102.

[0072] For example, the diagnostic process may include checking (e.g., using a current comparator) whether the current supplied to I / O pin 101C is higher than a certain threshold during each "on" time of the PWM power signal supplied to I / O pin 101C. If yes, an "overcurrent event" flag can be set to indicate that an overcurrent event has been detected. The overcurrent detection process can be disabled when the current "on" time of the PWM power signal expires.

[0073] In one or more embodiments, the overcurrent detection process may be enabled during a number of (subsequent) "on" times of the PWM power signal, and the detected overcurrent event may be reported (only) after a number of "on" times of the PWM power signal.

[0074] Optionally, the diagnostic process may include waiting for a blanking time at the beginning of each new PWM cycle of the PWM power signal supplied to the I / O pin 101C before enabling the overcurrent detection mechanism.

[0075] Figure 5 This is an exemplary flowchart of possible steps of the diagnostic process 50 included in one or more embodiments.

[0076] Initialization step 500 may include defining variables for performing the diagnostic process. As is known in the art, the PWM power supply signal can be determined by the "on" time T. on and the "off" time T offThe turn-off characteristic is that the sum of the on-time and off-time equals the PWM cycle duration T. per Duration of the period T per It can be fixed or programmable (e.g., equal to 10 ms). The duration T of the conduction time. on It can be variable, for example, because it is defined as a function of the compensation algorithm run by processing circuit 21. Additionally, the blanking time T can be defined. blanking Blanking time T blanking It can be the initial part of each cycle of a PWM power supply signal for which no overcurrent event has been detected.

[0077] For example, the blanking time T blanking It can be equal to 40 μs. Typically, the conduction time T... on Higher than the blanking time T blanking Furthermore, the maximum number N of "on" pulses for the PWM power signal can be defined. max During this period, an overcurrent event was detected and verified. For example, N max It can be equal to 5. Furthermore, the overcurrent detection blanking time T can be defined. OC_blanking Overcurrent detection blanking time T OC_blanking It can be defined at the current “on” time T on The minimum duration of an overcurrent condition is counted as an overcurrent event.

[0078] Therefore, in one or more embodiments, the initialization step 500 may include defining the following variable: pulse counter N (signed, ranging from -1 to N). max +1) Overcurrent bit OC, overcurrent event bit N max Overcurrent counter T OC Blanking time counter T blanking and PWM pulse counter T ON .

[0079] like Figure 5 As shown, subsequent parts of the diagnostic procedure 50 may include steps 502 through 514 for generating the blanking time. Step 502 may include setting the PWM power supply signal to a low value (e.g., zero), disabling overcurrent detection, stopping and resetting any counters. Step 504 may include checking whether the PWM power supply signal must be turned on and whether the overcurrent flag is cleared.

[0080] If the result of step 504 is negative (No), the process can return to step 502. If the result of step 504 is positive (Yes), the process can continue to step 506. Step 506 may include setting the pulse counter N to zero. Step 508 may include setting the overcurrent bit OC to zero and setting the PWM power supply signal to a high value (e.g., -). Step 510 may include starting the blanking time counter T. blanking and PWM pulse counter T on Step 512 may include checking whether the PWM power signal is turned off by the microcontroller 102.

[0081] If the result of step 512 is positive (Yes), the process can return to step 502. If the result of step 512 is negative (No), the process can continue to step 514. Step 514 may include checking whether the blanking time has elapsed (e.g., whether the blanking time counter has reached a threshold). If the result of step 514 is negative (No), the process can return to step 512. If the result of step 514 is positive (Yes), the process can continue to step 516.

[0082] Step 516 initiates the subsequent portion of the diagnostic process 50, including steps 516 through 528 for detecting and managing overcurrent events. Step 516 may include setting the overcurrent event bit to OC. event Set to zero to reset the overcurrent counter T. OC And enable with equal to T OC_blanking Overcurrent detection during blanking time. Subsequent steps 518 to 524 can be executed simultaneously with steps 600 to 610 of the overcurrent detection process 60, such as... Figure 6 As shown.

[0083] Specifically, the overcurrent detection process may include step 600, which includes checking whether overcurrent detection is enabled.

[0084] If the result of step 600 is negative (no), the process can return to step 600.

[0085] If the result of step 600 is positive (yes), the process can continue to step 602. Step 602 may include checking whether the current supplied to I / O pin 101C exceeds a threshold.

[0086] If the result of step 602 is negative (No), the process can continue to step 604. If the result of step 602 is positive (Yes), the process can continue to step 606. Step 604 may include setting the overcurrent counter T... OC Set to zero. Step 606 may include setting the overcurrent counter T to zero. OC Set to blanking time TOC_blanking With overcurrent counter T OC Add a circuit to the current value (i.e., T) OC =min(T) OC_blanking ;T OC +1)) minimum value. Step 608 may include checking the overcurrent counter T OC Is the current value higher than or equal to the blanking time T? OC_blanking .

[0087] If the result of step 608 is negative (No), the process can return to step 600. If the result of step 608 is positive (Yes), the process can continue to step 610. Step 610 may include setting the overcurrent event bit OC. event Set to 1.

[0088] With Figure 6 The overcurrent detection process 60 shown can simultaneously execute steps 518 to 524. Step 518 may include checking the overcurrent event bit OC. event Is it equal to one?

[0089] If the result of step 518 is positive (yes), the process can continue to step 520.

[0090] If the result of step 518 is negative (No), the process may continue to step 522. Step 520 may include setting the overcurrent bit OC to one. Step 522 may include checking whether the "on" time T of the PWM power signal has elapsed. on (For example, PWM pulse counter T) on Has the threshold been reached?

[0091] If the result of step 522 is negative (No), the process can continue to step 524. If the result of step 522 is positive (Yes), the process can continue to step 528. Step 524 may include checking whether the PWM power signal is turned off by the microcontroller 102.

[0092] If the result of step 524 is negative (No), the process can return to step 518. If the result of step 524 is positive (Yes), the process can continue to step 526. Step 526 may include disabling overcurrent detection. After step 526, the process can return to step 502. Step 528 may include disabling overcurrent detection. After step 528, the process can continue to step 530.

[0093] Step 530 begins with a follow-up portion of the diagnostic process 50, steps 530 through 544, for generating the “off” time of the PWM power supply signal and checking for the occurrence of a verified overcurrent event, based on which the driver element can be turned off. Step 530 may include checking whether the overcurrent bit OC is equal to one.

[0094] If the result of step 530 is negative (No), the process can continue to step 532. If the result of step 530 is positive (Yes), the process can continue to step 540. Step 532 may include setting the pulse counter N to zero and decrementing the current value of the pulse counter N by one (i.e., ,n =max(0; N-1)) maximum value. Step 534 may include setting the PWM power supply signal to a low value (e.g., zero) and starting the PWM shutdown counter T. OFF Step 536 may include checking whether the PWM power signal is turned off by the microcontroller 102. If the result of step 536 is positive (yes), the process may return to step 502.

[0095] If the result of step 536 is negative (No), the process can continue to step 538. Step 538 may include checking whether the "off" time T of the PWM power signal has elapsed. off (For example, PWM shutdown counter T) OFF Has the threshold been reached?

[0096] If the result of step 538 is negative (No), the process can return to step 536. If the result of step 538 is positive (Yes), the process can return to step 508. Step 540 may include setting the pulse counter N to N0. max The current value of pulse counter N is increased by the minimum value in the circuit (i.e., ,n =min(N) max Step 542 may include checking whether the current value of the pulse counter N is equal to or greater than the quantity N. max .

[0097] If the result of step 542 is negative (No), the process can return to step 534. If the result of step 542 is positive (Yes), the process can continue to step 544. Step 544 may include reporting the value of the overcurrent bit OC and turning off the PWM power supply signal (e.g., turning off the driver element).

[0098] Therefore, one or more embodiments can provide systems and methods for driving lighting loads (e.g., LED groups) with flexible and programmable brightness compensation architectures, and are also applicable in cases where multiple lighting loads are coupled in parallel to the same PWM power supply pin.

[0099] Therefore, one or more embodiments may provide one or more of the following advantages: each lighting load (e.g., a single LED or a group of LEDs) can be driven (e.g., programmed) at its own brightness level, while the duty cycle of the corresponding PWM power supply voltage can still be determined by the driver circuit 101 for the battery voltage V. BAT The microcontroller 102 independently manages the duty cycle and dimming ramp in the case of multiple lighting loads coupled in parallel, while more time-critical tasks (e.g., power supply voltage compensation) are performed by the driver circuit 101 (e.g., implemented as an ASSP), which can compensate for the number of lighting loads higher than the number of output stages of the driver circuit 101 (e.g., the number of high-side driver elements 30) in real time without relying on direct drive inputs (e.g., directly driving the high-side PWM input signal); for compensating battery voltage V BAT The established solution for the variations can be extended to a higher number of lighting loads without redesigning the driver circuit 101, as long as brightness control is achieved by means of external circuitry controlled by the system microcontroller 102. This may eliminate any limitation on the number of lighting loads that can be coupled to the driver circuit 101. In the case of lighting circuit events in parallel-coupled lighting circuitry 101, and in the case of parallel compensation circuitry, a large number of lighting loads can be independently dimmed or set to different brightness levels under the control of external circuitry of the system microcontroller 102 without redesigning the driver circuitry.

[0100] As illustrated in this article, the system (e.g.) ,1 00') may include microcontroller circuitry (e.g. ,1 02) Coupling (e.g.) ,1 05) Driver circuits (e.g., to the microcontroller circuit to receive data from the microcontroller circuit) ,1 01), and includes multiple output power pins coupled to multiple output power pins (e.g., ...). ,1 01C1、… ,1 01C n ), multiple lighting devices (e.g., 31) 1,1 ... 31 1,m 31 n (), wherein the plurality of lighting devices includes at least one subset of lighting devices coupled to the same output power pin among a plurality of output power pins, and a set of corresponding electronic switches of the lighting devices coupled in series to at least one subset of the lighting devices.

[0101] As illustrated herein, the driver circuit can be configured to selectively apply a power supply voltage (e.g., V)BAT ) spread (e.g., 301, ..., 30 n ) to the output power pin to provide the corresponding pulse width modulated power signal (e.g., V) at the output power pin. BAT,1 V BAT,n The microcontroller circuitry calculates the corresponding duty cycle value of the pulse-width modulated power signal based on data received from the microcontroller circuitry. The microcontroller circuitry can be configured to control the signal via a corresponding control signal (e.g., P...). 1,1 ... P 1,m The electronic switches are controlled individually to adjust the brightness of at least one subset of the lighting equipment.

[0102] As illustrated herein, a lighting device may include one or more light-emitting diodes.

[0103] As illustrated in this article, the driver circuit can be configured to sense the value of the power supply voltage (e.g., V). S It can be configured to calculate the corresponding duty cycle value of the pulse width modulated power signal based on the value of the sensed power supply voltage.

[0104] As illustrated herein, the control signal may be a pulse-width modulated control signal having a frequency higher than that of the pulse-width modulated power supply signal, optionally having a frequency 10 to 20 times higher than that of the pulse-width modulated power supply signal.

[0105] As illustrated herein, the corresponding electronic switches of the lighting devices, which are series-coupled to at least a subset of the lighting devices, may include a corresponding first transistor (e.g., T2) having a corresponding control terminal controlled by a corresponding control signal. 1,1 ..., T21 ,m ).

[0106] As illustrated herein, the signal propagation network from the microcontroller circuitry to the corresponding first transistor for each control signal in the control signals may include: a control node (e.g., 40 1,1 401 ,m The circuit is configured to receive corresponding control signals from a microcontroller circuit; and a current path coupled between a corresponding output power supply pin of the driver circuit and ground, said current path including a first resistor (e.g., R1). 1,1 ..., R1 1,m ), and the second resistor (e.g., R2) 1,1 R2 1,m ) and another transistor (e.g., T1) 1,1 ..., T1 1,m ) in series arrangement.

[0107] As illustrated herein, the control terminal of another transistor can be coupled (e.g., R4). 1,1 ..., R4 1,m The control terminal of the first transistor can be coupled to the node between the first resistor and the second resistor.

[0108] As illustrated herein, the driver circuit can be configured to measure the current supplied to the output power pin during the on-time of the pulse-width modulated power signal, check whether the current supplied to the output power pin is higher than an overcurrent threshold, and detect an overcurrent event in response to the current supplied to the output power pin being higher than the overcurrent threshold.

[0109] As illustrated herein, the driver circuit can be configured to measure the blanking period that has elapsed since the on-time of the pulse width modulation power signal, and to measure the current supplied to the output power pin as the measured blanking period reaches the blanking threshold.

[0110] As illustrated herein, the driver circuit can be configured to check whether the current supplied to the output power pin is higher than an overcurrent threshold during the duration of the measurement period, and to detect an overcurrent event in response to the current supplied to the output power pin being higher than the overcurrent threshold during the duration of the measurement period.

[0111] As illustrated herein, the driver circuitry can be configured to detect an overcurrent event in response to a current supplying the output power pin exceeding an overcurrent threshold during multiple subsequent on-times of the pulse-width modulated power signal.

[0112] As illustrated herein, a method may include: generating a plurality of pulse width modulated power signals for supplying a plurality of lighting devices; supplying an identical pulse width modulated power signal from the plurality of pulse width modulated power signals to at least one subset of the lighting devices in the plurality of lighting devices; generating a corresponding control signal supplied by the identical pulse width modulated power signal for each lighting device in the subset of lighting devices; and individually coupling and decoupling each lighting device in the subset of lighting devices from the identical pulse width modulated power signal according to the corresponding control signal to individually adjust the brightness of the lighting devices in the at least one subset of lighting devices.

[0113] As illustrated herein, one approach may include: measuring the current supplied to a lighting device during the on-time of a pulse-width modulated power signal; checking whether the current supplied to the lighting device is higher than an overcurrent threshold; and detecting an overcurrent event in response to the current supplied to the lighting device being higher than the overcurrent threshold.

[0114] Without prejudice to the basic principles and without departing from the scope of protection, the details and embodiments may vary significantly with respect to what has been described by way of example only.

[0115] It should be understood that the embodiments of this disclosure are not limited to the applications disclosed herein concerning the measurement of voltage drop at a spare capacitor in an auxiliary constraint system. Various embodiments are also applicable to other applications that benefit from measuring voltage drop at the terminals of electronic circuits with unknown baseline voltages.

[0116] Therefore, the specification and drawings are to be regarded only as a description of this disclosure as defined by the appended claims, and are intended to cover any and all modifications, variations, combinations or equivalents falling within the scope of this disclosure.

Claims

1. A system for driving a lighting device, comprising: microcontroller; A driver circuit, coupled to the microcontroller, includes multiple output power pins and is configured to: Receive data from the microcontroller Selectively propagate the power supply voltage to the output power supply pin to transmit a pulse-width modulated power signal at the corresponding output power supply pin, and The duty cycle value of the pulse width modulation power signal at the corresponding output power pin is calculated based on the data received from the microcontroller. Multiple lighting devices are coupled to the multiple output power pins, wherein a subset of the multiple lighting devices is coupled in parallel to a single output power pin of the multiple output power pins; as well as A set of electronic switches, comprising a corresponding electronic switch for each of at least one subset of a plurality of lighting devices, coupled in series. The microcontroller is configured to individually control each of the electronic switches via a corresponding control signal to individually adjust the brightness of the subset of the plurality of lighting devices; The control signal is a pulse-width modulated control signal, and the frequency of the pulse-width modulated control signal is higher than the frequency of the pulse-width modulated power supply signal.

2. The system of claim 1, wherein the plurality of lighting devices comprises light-emitting diodes.

3. The system of claim 1, wherein the driver circuit is configured as follows: The value of the power supply voltage is sensed; and The second duty cycle value of the pulse width modulation power signal at the corresponding output power pin is calculated based on the value of the power supply voltage.

4. The system according to claim 1, wherein the frequency of each pulse width modulation control signal in the pulse width modulation control signal is between 10 and 20 times the frequency of the pulse width modulation power supply signal.

5. The system of claim 1, wherein each electronic switch includes a first transistor having a corresponding control terminal controlled by the corresponding control signal.

6. The system of claim 5, wherein the signal propagation network for each control signal to the corresponding first transistor comprises: A control node is configured to receive the corresponding control signal from the microcontroller; as well as A current path, coupled between the corresponding output power pin and ground, includes a series arrangement of a first resistor, a second resistor, and a second transistor, wherein the control terminal of the second transistor is coupled to the control node of the second transistor, and wherein the control terminal of the first transistor is coupled to the node between the first resistor and the second resistor.

7. The system of claim 1, wherein the driver circuit is configured to: Measure the value of the current supplied to the corresponding output power pin during the on-time of the pulse width modulation power signal; Determine whether the value of the current is greater than the overcurrent threshold; and An overcurrent event is detected in response to the value of the current supplied to the corresponding output power pin being greater than the overcurrent threshold.

8. The system of claim 7, wherein the driver circuit is configured to: The blanking time period, starting from the on-time of the pulse-width modulated power signal, is measured at the corresponding output power pin; and Measure the value of the current supplied to the corresponding output power supply pin when the blanking time period reaches the blanking threshold.

9. The system of claim 7, wherein the driver circuit is configured to: Determine whether the current supplied to the corresponding output power pin during the duration of the measurement period is greater than the overcurrent threshold; and An overcurrent event is detected in response to the current supplied to the corresponding output power pin being greater than the overcurrent threshold during the duration of the measurement time period.

10. The system of claim 7, wherein the driver circuit is configured to detect an overcurrent event in response to a current value supplied to the corresponding output power pin being greater than the overcurrent threshold during a plurality of subsequent on-times of the pulse width modulated power signal at the corresponding output power pin.

11. A method for driving a lighting device, comprising: Generate multiple pulse width modulated power signals; A single pulse width modulation power signal from the plurality of pulse width modulation power signals is provided to at least one subset of the plurality of lighting devices that are coupled in parallel to the plurality of lighting devices, wherein each lighting device in the subset of lighting devices receives the same pulse width modulation power signal; A corresponding control signal is generated for each lighting device in the subset of the plurality of lighting devices. The control signal is independently controlled for each lighting device relative to the single pulse width modulated power signal. The control signal is a pulse width modulated control signal with a frequency higher than that of the pulse width modulated power signal. as well as The brightness of the subset of the plurality of lighting devices is individually adjusted by coupling and decoupling each lighting device in the subset of the plurality of lighting devices with the single pulse width modulation power supply signal according to the control signal.

12. The method of claim 11, further comprising: Measure the value of the current supplied to the lighting device during the on-time of the pulse width modulation power signal; as well as Determine whether the value of the current is greater than the overcurrent threshold; as well as An overcurrent event is detected in response to the current value being greater than the overcurrent threshold.

13. The method of claim 11, wherein the plurality of lighting devices comprises light-emitting diodes.

14. A method of operating a device, the method comprising: Data is received from the microcontroller by a driver circuit, which includes multiple output power pins. The power supply voltage is selectively propagated to the output power supply pin to transmit a pulse width modulated power supply signal at the corresponding output power supply pin; The duty cycle of the pulse-width modulated power signal at the corresponding output power pin is calculated based on the data received from the microcontroller, wherein the control signal is a pulse-width modulated control signal and the frequency of the pulse-width modulated control signal is higher than the frequency of the pulse-width modulated power signal. as well as The microcontroller individually controls a corresponding electronic switch in a set of electronic switches via corresponding control signals to individually adjust the brightness of a subset of multiple lighting devices, said devices including multiple lighting devices coupled to said multiple output power pins. The subset of the plurality of lighting devices is coupled in parallel to a single output power pin of the plurality of output power pins, and the electronic switch is coupled in series to each lighting device in at least one subset of the plurality of lighting devices.

15. The method of claim 14, further comprising: The value of the power supply voltage is sensed by the driver circuit; as well as The driver circuit calculates the second duty cycle value of the pulse width modulation power signal at the corresponding output power pin based on the value of the power supply voltage.

16. The method of claim 14, wherein each control signal is a pulse-width modulated control signal, the pulse-width modulated control signal having a frequency higher than the frequency of the pulse-width modulated power supply signal.

17. The method of claim 16, wherein the frequency of each control signal is between 10 and 20 times the frequency of the pulse width modulated power supply signal.

18. The method of claim 14, further comprising: The value of the current supplied to the corresponding output power pin during the on-time of the pulse width modulation power signal is measured by the driver circuit. The driver circuit determines whether the value of the current is greater than the overcurrent threshold. as well as An overcurrent event is detected by the driver circuit in response to the value of the current supplied to the corresponding output power pin being greater than the overcurrent threshold.

19. The method of claim 18, further comprising: The blanking time period, starting from the on-time of the pulse width modulation power signal, is measured by the driver circuit at the corresponding output power pin. as well as The value of the current supplied to the corresponding output power supply pin is measured by the driver circuit as the measured blanking time period reaches the blanking threshold.

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