CN216820152U - Driving circuit for LED and LED lighting device - Google Patents
Driving circuit for LED and LED lighting device Download PDFInfo
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- CN216820152U CN216820152U CN202122404015.2U CN202122404015U CN216820152U CN 216820152 U CN216820152 U CN 216820152U CN 202122404015 U CN202122404015 U CN 202122404015U CN 216820152 U CN216820152 U CN 216820152U
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Abstract
The application relates to a power supply circuit, and provides a driving circuit for an LED and an LED lighting device, which comprises a converter, an integrated circuit controller and a de-enabling circuit, wherein the integrated circuit controller is connected to the converter and used for controlling the power conversion of the converter; a disable circuit is coupled to the integrated circuit controller for disabling the certain function of the integrated circuit controller when the driver circuit is activated and terminating the disabling of the certain function of the integrated circuit controller after the driver circuit is activated. The disable circuit limits the number of functions that the integrated circuit controller is prone to false triggering at start-up, which once triggered, may cause the converter to operate at a less than desired level, thereby ensuring that the converter operates at the desired level.
Description
Technical Field
The application belongs to the technical field of power supply circuits, and particularly relates to a driving circuit for an LED and an LED lighting device.
Background
Currently, a switching power supply is commonly used for LED (light emitting diode) driving, and the switching power supply provides a constant current for the LED. Many switching power supplies are controlled by integrated circuit controllers. For some integrated circuit controllers, when the output voltage of the switching power supply is not sufficiently established during startup, some integrated circuit controllers increase the output current, and when the output voltage is too low and the output current exceeds a safety regulation value, the safety regulations such as UL (Underwriter Laboratories Inc.) are not satisfied. When the output voltage is not fully established, once the output current is detected to be larger than a certain threshold value, the other integrated circuit controllers consider that the output is short-circuited to enter a protection state, so that the switching power supply controlled by the integrated circuit controllers can be put into a false protection state when working in cooperation with another power supply, and the switching power supply can fail to be started.
SUMMERY OF THE UTILITY MODEL
The application aims to provide a driving circuit for an LED and an LED lighting device, and aims to solve the problem that when a traditional LED is driven and started, an integrated circuit controller of the driving circuit triggers an unexpected triggering function due to the fact that the output of the traditional LED does not reach a normal state temporarily, and further the LED driving circuit works abnormally, for example, the LED driving circuit does not meet safety specifications or fails to start. The basic idea of the utility model is that for the drive circuit for LED controlled by the integrated circuit controller with certain function, when the drive circuit for LED is started, the certain function of the integrated circuit controller is disabled to enable the drive circuit to work normally; the disabling of the certain function may be disabled until the completion of the booting. In a specific embodiment, the certain function of the integrated circuit controller is disabled when the output voltage of the LED driver circuit is not sufficiently built. In some embodiments, its fast start function is disabled to reduce the output current to avoid violating safety regulations; or in other embodiments, to enable its protection function to prevent the protection function from causing the switching power supply to fail to start up.
A first aspect of embodiments of the present application provides a driving circuit for an LED, including
An input for receiving input power;
a converter for power converting the input power;
an output for being connected to the LED to output the converted input power to the LED;
an integrated circuit controller connected to the converter for controlling the power conversion by the converter, the integrated circuit controller including a function;
the drive circuit further includes:
a disable circuit, coupled to the integrated circuit controller, for disabling the certain function of the integrated circuit controller when the driving circuit is started and terminating the disabling of the certain function of the integrated circuit controller after the driving circuit is started.
In this embodiment, a disable circuit is added to the driving circuit for the LED to prevent the integrated circuit controller from triggering some functions that are not expected to be triggered when the driving circuit is started, thereby preventing the driving circuit from operating abnormally. For example, the functions are protection functions, such as some protection functions for identifying abnormal conditions such as undervoltage, overcurrent, overvoltage and the like, and the protection functions may prevent the drive circuit from being started under some working conditions, so that the embodiment of the application can ensure that the drive circuit can be started under the working conditions, and the problem that the drive circuit enters a protection state due to error protection of an integrated circuit controller when being started, so that the start failure is caused is avoided; and disabling of the certain function of the integrated circuit controller is terminated after the outputs of the driver circuit are expected, thereby restoring the protection function. For another example, where these functions are fast start functions that may cause the driver circuit to operate beyond safety specifications, embodiments of the present application avoid the fast start of the driver circuit from actually occurring, thereby causing the driver circuit to operate within safety specifications.
In one embodiment, the driving circuit further includes a main PFC circuit for performing PFC conversion on the input power and outputting the converted input power to the LED, and the converter is configured to compensate for fluctuation of an output of the main PFC circuit, wherein the output of the main PFC circuit and the converter are connected in series to the LED.
The above embodiments have exemplified an operating condition applied to the driver circuit in which it operates in tandem with the output of a main PFC circuit, in which case the output of the main PFC circuit flows through the driver circuit and is detected by the integrated circuit controller, or even recognized as a fault. Therefore, the utility model of the present application is needed to solve the problem.
In one embodiment, the certain functionality of the integrated circuit controller includes a short circuit protection function that protects to shut down the converter when an output voltage of the converter is below a first voltage threshold and a current flowing through the converter is above a first current threshold;
the disable circuit is to prevent the output current of the main PFC circuit from producing a current in the converter that exceeds the first current threshold when the output voltage of the converter has not been established to the first voltage threshold to disable the short-circuit protection function to avoid shutting down the converter.
In this embodiment, the disable circuit can avoid triggering the short-circuit protection function of the integrated circuit controller, so that the converter can be normally started before the output voltage of the converter reaches the first voltage threshold.
Specifically, when the main PFC circuit is started, the main PFC circuit may already output current to drive the LED and flow through the converter, and the converter may not be completely started, for example, the output voltage of the converter is not completely established, in this case, if the technical solution of the present application is not adopted, the original protection function of the integrated circuit controller of the converter will detect that the output voltage of the converter is insufficient but there is already current (from the main PFC circuit), and it is mistaken that this is caused by a fault condition such as a load short circuit, and thus the integrated circuit controller enters into protection, and the converter cannot continue to operate. To solve this problem, the present application provides a disable circuit that disables the protection function before the output voltage of the converter is fully established, thereby preventing the integrated circuit controller from entering a protection mode to keep the driving circuit operating. Preferably, the disabling of the protection function is deactivated after the output voltage is established.
In one embodiment, the disable circuit includes an open switch connected in a series circuit between the output of the main PFC circuit and the converter, the open switch being configured to open the connection between the main PFC circuit and the converter to open a current loop from the main PFC circuit to the converter when the output voltage of the converter has not been established to the first voltage threshold, and to close the connection to open the current loop from the main PFC circuit to the converter after the output voltage of the converter has been established to the first voltage threshold such that the output current of the main PFC circuit flows through the LED and the converter.
This embodiment provides an implementation of a disable circuit that directly disconnects the current flowing from the main PFC circuit to the converter, so that the integrated circuit controller of the converter does not detect the current and therefore does not trigger short circuit protection. The open circuit switch can be a semiconductor switch tube, an electronic switch or a relay, and the like, and has the advantages of simple and reliable scheme and low cost.
In one embodiment, the disable circuit further comprises a trigger circuit connected between the output and the control terminal of the open switch for detecting the output voltage and comparing it to the first voltage threshold, the trigger circuit opening the open switch when the output voltage of the converter has not yet been established to the first voltage threshold and closing the open switch after the output voltage of the converter has been established to the first voltage threshold.
The embodiment provides a driving example of an open switch of a disable circuit, which utilizes a trigger circuit to detect an output voltage, and configures the detected voltage component to be compared with a preset first voltage threshold, and drives the open switch to be turned on when the voltage component exceeds the first voltage threshold, so that the driving circuit is started, and the protection module is prevented from entering.
In another embodiment, the certain function of the integrated circuit controller includes a fast start function, which controls the output current of the converter not to fall below a second current threshold when the output voltage of the converter is below a second voltage threshold, the second current threshold being a maximum value allowed by UL safety specifications, for example 150 divided by the maximum output voltage of the driving circuit.
In this embodiment, the original fast start function of the integrated circuit controller may be a violation of UL security specifications, and therefore the present invention can be used to solve this conflict.
Accordingly, in one embodiment, the disable circuit is configured to disable the fast start function to prevent the integrated circuit controller from controlling the output current of the converter to be greater than the second current threshold when the output voltage of the converter has not been established to the second voltage threshold.
In this embodiment, the disable circuit can prevent the ic controller from actually controlling the driving circuit to start quickly, so that the output current of the converter is within the safety current range (150 divided by the maximum output voltage of the driving circuit), and the safety specification, such as UL (Underwriter Laboratories Inc). It is noted that said "disabling said fast start function to prevent said integrated circuit controller from controlling said converter output current to be greater than said second current threshold" includes two conditions: if the integrated circuit controller has a dedicated control terminal for enabling/disabling the fast start function, the embodiment may set a corresponding control signal on the dedicated control terminal; if the ic controller does not have the corresponding control terminal, this embodiment allows the ic controller to enable the fast start function itself but reduce the output current of the driving circuit actually controlled by the ic controller through other peripheral methods. Both of these conditions fall into the range of "disable the quick start function to prevent the integrated circuit controller from controlling the output current of the converter to be greater than the second current threshold".
In one embodiment, the integrated circuit controller includes a sense terminal for sensing the output current, and the disable circuit is coupled to the sense terminal for applying a forward bias to the sense terminal to prevent the output current of the converter from being greater than the second current threshold when the output voltage of the converter has not been established to the second voltage threshold, and for removing the forward bias after the output voltage of the converter has been established to the second voltage threshold.
In this embodiment, the integrated circuit controller sets the output current of the converter according to the magnitude of the voltage applied to the sensing terminal of the integrated circuit controller, and even in the case that the integrated circuit controller triggers the quick start function, the integrated circuit controller considers that the output current is too large when the voltage of the sensing terminal is large and then reduces the output current. Thus, the disable circuit in this embodiment will apply a forward bias to the sense terminal of the integrated circuit controller to cause the output current of the converter during start-up to be lower than that specified by safety regulations, thereby inhibiting the aforementioned fast start-up function. After the output voltage is established to the threshold value, the integrated circuit controller automatically exits the fast start function, and accordingly the forward bias is removed in this embodiment, so that the driving circuit operates normally.
In one embodiment, the integrated circuit controller includes a dimming terminal for receiving a dimming control signal, and the disable circuit is coupled to the dimming terminal for applying a negative bias to the dimming terminal to prevent the output current of the converter from being greater than the second current threshold when the output voltage of the converter has not been established to the second voltage threshold, and for removing the negative bias after the output voltage of the converter has been established to the second voltage threshold.
In this embodiment, the integrated circuit controller configures the output current of the converter according to the voltage applied to the dimming terminal, and even if the integrated circuit controller itself triggers the quick start function, the integrated circuit controller will reduce the output current when the voltage of the dimming terminal is small. Thus, the disable circuit in this embodiment will apply a negative bias to the dimmer terminal of the integrated circuit controller to cause the output current of the converter during start-up to be lower than that specified by safety regulations, thereby inhibiting the aforementioned rapid start-up function. After the output voltage is established to the threshold value, the integrated circuit controller automatically exits the fast start function, and accordingly the negative bias is removed in this embodiment, and the driving circuit can normally operate.
In one embodiment, the disable circuit comprises:
a bias circuit connected to the integrated circuit controller for providing the bias;
a comparator circuit coupled to the converter and further coupled to the bias circuit, the comparator circuit configured to detect an output voltage of the converter and compare the detected output voltage with the second voltage threshold, apply the bias to a sense terminal or a dimming terminal of the integrated circuit controller when the detected output voltage is lower than the second voltage threshold, and isolate the bias from the sense terminal or the dimming terminal of the integrated circuit controller when the detected output voltage is higher than the second voltage threshold.
In this embodiment, a specific implementation of a disable circuit for preventing the integrated circuit controller from entering the over-current protection is provided, the bias circuit is used for providing a positive/negative bias for configuring the magnitude of the output current, and the comparison circuit is used for configuring whether the bias circuit provides the bias according to the output voltage of the converter, so that the driving circuit can start normally.
Other aspects of the present application also provide an LED lighting device comprising an LED, and the aforementioned driving circuit, the LED being connected at an output of the driving circuit.
The above-mentioned and non-mentioned advantages of the present application will be described in the detailed description section or will be understood by those of ordinary skill in the art with reference to the following drawings.
Drawings
Fig. 1 is a schematic structural diagram of a driving circuit for an LED according to an embodiment of the present disclosure;
FIG. 2 is a first exemplary circuit schematic of the drive circuit shown in FIG. 1;
fig. 3 is a second exemplary circuit schematic of the driving circuit shown in fig. 1.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.
It will be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, refer to an orientation or positional relationship illustrated in the drawings for convenience in describing the present application and to simplify description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present application.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more, and "several" means one or more unless specifically limited otherwise.
Referring to fig. 1, the driving circuit for LED according to the embodiment of the present application includes an input 11, an inverter 12, an output 13, an integrated circuit controller 14, and a disable circuit 15.
An integrated circuit controller 14 is connected to the converter 12 for controlling the power conversion by the converter 12, the integrated circuit controller 14 including functions such as overcurrent protection, overvoltage protection, short circuit protection, fast start/charge, dimming, etc. It is noted that one or more of these functions may be triggered at startup so that the operating state of the converter 12 is not the desired operating state. Therefore, the present application also includes a disable circuit 15, coupled to the integrated circuit controller 14, for disabling certain functions of the integrated circuit controller 14 upon start-up of the driving circuit to avoid an undesired operating state of the converter 12, where "coupled" includes direct electrical connections and also includes any circuit arrangement that is capable of logically implementing "disable", i.e., any circuit connection in the driving circuit that is capable of disabling the certain functions of the integrated circuit controller, of the disable circuit 15 is within the scope of "coupled". Preferably, disabling certain functions of the integrated circuit controller 14 is terminated after the drive circuit is started to ensure that the drive circuit continues to operate normally.
In one embodiment, the converter 12 is configured to operate in conjunction with another power circuit. Specifically, referring to fig. 2, the driving circuit further includes a main PFC (Power Factor Correction) circuit 16 for performing PFC conversion on the input Power and outputting the converted input Power to the LED, and the converter 12 for compensating for the fluctuation of the output of the main PFC circuit 16, wherein the output of the main PFC circuit 16 and the converter 12 are connected in series to the LED.
The converter 12 of this embodiment works in conjunction with the main PFC circuit 16 to form an AC-DC architecture that cancels the AC frequency ripple output by the main PFC circuit 16, wherein the main PFC circuit 16 performs most of the power conversion, such as 90% or even higher of the total output power, and the converter 12 compensates for the ripple component of the output of the main PFC circuit 16, which may only account for 10% or even lower of the total output power. The output of the main PFC circuit 16 and the output 13 of the converter 12 are connected in series across LED D6. Such an AC-DC structure can realize a high Power Factor (PF) and a low output ripple, and compared with a conventional two-stage PFC + DC-DC (DC-DC is required to output all Power), the driving circuit of this embodiment only needs to output a small Power to eliminate the ripple of the main PFC, and thus is a solution with high efficiency and high Power density.
Typically, the main PFC circuit 16 operates in constant voltage control, which is a slow control loop to keep the power factor high. The converter 12 operates in constant current control, which is a fast control loop to compensate for ripple, e.g. 100 Hz. This architecture is inherently insubstantial, and in particular productions problems may arise when the integrated controller 14 is employed to control the converter 12.
For instance, in one example, certain functions of the integrated circuit controller 14 include a short circuit protection function that protects to turn off the converter 12 when the output voltage of the converter 12 is below a first voltage threshold and the current flowing through the converter 12 is above a first current threshold; the disabling circuit 15 is operable to prevent the output current of the main PFC circuit 16 from generating a current in the converter 12 that exceeds a first current threshold when the output voltage of the converter 12 has not yet been established to the first voltage threshold, to disable the short circuit protection function to avoid shutting down the converter 12. Ensuring the normal start of the driving circuit.
Specifically, the constant current buck is a converter widely used in LED and has a feature that when the output voltage is lower than the LED D6 forward voltage, LED D6 is not turned on and has no current and consumes no power, so the integrated circuit controller 14 for constant current buck is mostly unable to support the output current/power when the output voltage is lower. Thus, when the output voltage is low and there is output current/power consumption, the integrated circuit controller 14 will detect this as an under load and the integrated circuit controller 14 will trigger the short circuit protection mode. When the inverter 12 is used alone to drive an LED, the LED does not conduct and there is no current flow when the voltage is low, and thus the integrated circuit controller 14 is not protected. When the converter 12 and the main PFC circuit 16 are cooperatively used in the above-mentioned architecture, for example, when the main PFC circuit 16 operates, the voltage at the LED D6 is already about 400V, the LED D6 is already turned on, and the main PFC circuit 16 outputs a current, which also flows through the converter 12 (the current flows through the diode D7, the current detection resistor Rcs, and the inductor L2 in fig. 2 and returns to the main PFC circuit 16, that is, the current is already detected at the current detection resistor Rcs), and at this time, the output voltage of the converter 12 is not established (the voltage detection circuit R, R3 and the FB terminal in fig. 2 cannot detect a sufficient output voltage), so as to falsely trigger the integrated circuit controller 14 to enter the short-circuit protection mode.
In this embodiment, when main PFC circuit 16 is enabled, main PFC circuit 16 may have output current to drive the LEDs and flow through converter 12, and at this point converter 12 may not have been fully enabled, i.e., the output voltage of converter 12 has not been fully established, in which case integrated circuit controller 14 detects that the output voltage is insufficient and the current (provided by main PFC circuit 16) is too large, and considers this to be a fault condition, such that integrated circuit controller 14 enters into protection and converter 12 cannot operate normally.
Therefore, the disabling circuit 15 provided in the present application can disable the short-circuit protection mode before the output voltage is fully established. Specifically, disable circuit 15 shuts off the flow of output current from main PFC circuit 16 through converter 12 so that integrated circuit controller 14 does not detect the excessive current, thereby avoiding entry into the protection mode. After the output voltage of the converter 12 is established, the output current of the main PFC circuit 16 is turned on again to flow through the converter 12. Furthermore, while the output current of the main PFC circuit 16 is cut off from flowing through the converter 12, the disable circuit 15 may simultaneously cut off the output current of the main PFC circuit 16 from flowing through the LED D6 until the converter 12 is started and then flow through the LED D6 and the converter 12; it is also possible to let the output current of the main PFC circuit 16 flow through the LED D6 first, to let the LED D6 light up first (although the ripple on the PFC current is not compensated by the converter 12), and at the same time to allow the converter 12 to start up to build up the output voltage until the converter 12 starts up and the output voltage is built up, and then to let the current flow through the LED D6 and the converter 12, after which the ripple on the PFC current will be compensated by the converter 12.
Referring to fig. 2, in one embodiment, the disable circuit 15 includes an open switch Q1 connected in a series circuit of the output of the main PFC circuit 16, the LED D6 and the converter 12, and the open switch Q1 is configured to open the connection between the main PFC circuit 16 and the converter 12 to open the current loop from the main PFC circuit 16 to the converter 12 when the output voltage of the converter 12 is not yet established to the first voltage threshold, and close the connection to open the current loop from the main PFC circuit 16 to the converter 12 after the output voltage of the converter 12 is established to the first voltage threshold, so that the output current of the main PFC circuit 16 flows through the LED D6 and the converter 12.
In one embodiment, the disable circuit 15 further includes a trigger circuit coupled between the output 13 and a control terminal of the open switch Q1 for detecting and comparing the output voltage to a first voltage threshold, the trigger circuit opening the open switch Q1 when the output voltage of the converter 12 has not yet been established to the first voltage threshold and closing the open switch Q1 after the output voltage of the converter 12 has been established to the first voltage threshold.
The trigger circuit comprises a diode D1, resistors R7 and R8, a capacitor C5 and a voltage regulator tube Z1. In the prior art, if the open switch Q1 does not exist, the main PFC circuit 16 will supply power to the LED D6 before the voltage of the output capacitor E2 reaches the threshold, and this current will flow through the diode D7, the sampling resistor Rcs, and the inductor L2, and the current on the sampling resistor Rcs and the low voltage on the output capacitor E2 will cause the integrated circuit controller 14 to mistakenly consider that the output 13 is short-circuited and protected (not working). With the disable circuit 15 of the present application, the open switch Q1 is initially open, and after the converter 12 charges the output capacitor E2 to a certain threshold, the FB terminal of the integrated circuit controller 14 has detected that the output voltage has built up, which will no longer trigger short circuit protection. Meanwhile, after the capacitor C5 is charged for a delay time through the diode D1 and the resistor R8, the open switch Q1 is turned on, and then the main PFC circuit 16 and the converter 12 supply power to the LED together. The first voltage threshold may be configured using voltage dividing resistors R7, R8 and a capacitor C5, and is specifically set as an output voltage value at which the trigger circuit opens the open switch Q1.
In another embodiment, referring to fig. 3, certain functions of the integrated circuit controller 14 include a fast start function, which controls the output current of the converter 12 not to fall below a second current threshold when the output voltage of the converter 12 is lower than the second voltage threshold, wherein the second current threshold is a maximum value allowed by UL safety regulations, such as 150 divided by the maximum output voltage of the driving circuit. In this embodiment, the converter 12 is a Flyback converter, and the integrated circuit controller 14 for control has a fast start function, which when the output voltage is lower than a second voltage threshold (e.g., 1/3 which is less than the over-voltage protection (OVP) voltage), the integrated circuit controller 14 will increase the output current of the converter 12, which would otherwise be to quickly power the output 13 to quickly light the LED D6, but the increased output current may exceed 150 divided by the maximum output voltage of the driver circuit, which is not allowed under UL safety regulations, and is at risk of over (current) current.
Therefore, the embodiment of the present application provides the disable circuit 15, which is used to disable the fast start function of the integrated circuit controller 14 when the driving circuit is started, so as to avoid violating the UL safety specification due to overcurrent at the output 13, and to terminate the disabling of the fast start function of the integrated circuit controller 14 after the driving circuit is started, so as to ensure that the driving circuit can normally operate.
Specifically, the disabling circuit 15 is configured to disable the quick start function when the output voltage of the converter 12 has not yet been established to the second voltage threshold, so as to prevent the integrated circuit controller 14 from controlling the output current of the converter 12 to be greater than the second current threshold, so that the output current of the converter 12 is within a current range specified by safety regulations, thereby avoiding violating UL safety regulations and enabling the driving circuit to pass UL safety certification.
In one embodiment, the integrated circuit controller 14 includes a sense terminal for sensing the current of the output 13, and the disable circuit 15 is coupled to the sense terminal ISEN for applying a forward bias at the sense terminal ISEN to prevent the output current of the converter 12 from being greater than a second current threshold when the output voltage of the converter 12 has not been established to the second voltage threshold, and removing the forward bias after the output voltage of the converter 12 is established to the second voltage threshold. Generally, the integrated circuit controller 14 configures the output current of the converter 12 according to the magnitude of the voltage applied by its sensing terminal ISEN, and the larger the voltage, the larger the output current is considered to be, the larger the output current is, and the smaller the output current is. Thus, the disable circuit 15 in this embodiment will apply a forward bias to the sense terminal ISEN of the integrated circuit controller 14 so that the output current of the converter 12 during start-up is below the allowable upper limit value of the UL safety specification, and after the output voltage is established to the threshold value, the forward bias is removed and the drive circuit can operate normally.
In another embodiment, the integrated circuit controller 14 includes a dimming terminal ADIM for receiving the dimming control signal, and the disable circuit 15 is coupled to the dimming terminal ADIM for applying a negative bias to the dimming terminal ADIM to prevent the output current of the converter 12 from being greater than the second current threshold when the output voltage of the converter 12 has not been established to the second voltage threshold, and for removing the negative bias after the output voltage of the converter 12 is established to the second voltage threshold. Generally, the ic controller 14 configures the output current of the converter 12 according to the magnitude of the voltage applied to the dimming terminal ADIM, and the smaller the voltage, the smaller the output current is. Thus, the disable circuit 15 in this embodiment will apply a negative bias to the dim terminal ADIM of the integrated circuit controller 14 so that the output current of the converter 12 during start-up is below the over-current protection threshold, and after the output voltage is established to the threshold, the negative bias is removed and the driver circuit can operate normally.
Referring to fig. 3, which illustrates one embodiment of regulating the ISEN terminal voltage, the disable circuit 15 includes a bias circuit 152 and a comparison circuit 154, the bias circuit 152 coupled to the integrated circuit controller 14 for providing a bias; a comparator circuit 154 is coupled to the converter 12 and is also coupled to the bias circuit 152, the comparator circuit 154 being configured to detect an output voltage of the converter 12, wherein the voltage Vaux is proportional to the output voltage, and to compare the detected output voltage to a second voltage threshold, to apply a bias to the sensing terminal ISEN of the integrated circuit controller 14 when the detected output voltage is below the second voltage threshold, and to isolate the bias from the sensing terminal ISEN of the integrated circuit controller 14 when the detected output voltage is above the second voltage threshold.
The bias circuit 152 includes a linear power supply V3 that generates a dc voltage that can be either a positive voltage (i.e., providing a positive bias) or a negative voltage (i.e., providing a negative bias).
Referring to fig. 3, in one embodiment, when the bias circuit 152 is connected to the sensing terminal ISEN of the integrated circuit controller 14, the bias circuit 152 is configured to output a positive voltage, which can be applied to the sensing terminal ISEN of the integrated circuit controller 14 through the diodes D8, D5 for providing a forward bias to the sensing terminal ISEN.
In another embodiment, not shown, when the bias circuit 152 is coupled to the dimming terminal ADIM of the integrated circuit controller 14, the bias circuit 152 is configured to output a negative voltage that is applied to the dimming terminal ADIM of the integrated circuit controller 14 for providing a negative bias to the dimming terminal ADIM. Thereby enabling the fast start-up function of the integrated circuit controller 14.
Referring to fig. 3, the comparison circuit 154 is mainly used to determine whether to provide the bias provided by the bias circuit 152 to the integrated circuit controller 14, wherein the determination criterion is based on whether the output voltage reaches the second voltage threshold. The comparison circuit 154 includes a zener diode D4 and an NPN transistor Q2 connected between the negative terminal of the diode D8 and ground, the negative terminal of the zener diode D4 is connected to the auxiliary winding L3, and the auxiliary winding L3 absorbs the leakage inductance of the primary winding L1 to induce a voltage Vaux proportional to the output voltage. When the output voltage of the converter 12 is less than the second voltage threshold, the voltage Vaux is less than the breakdown voltage of the zener diode D4, the zener diode D4 is non-conductive, the transistor Q2 is non-conductive, and the bias of the bias circuit 152 is applied to the sensing terminal ISEN of the integrated circuit controller 14 to reduce the output current. When the output voltage of the converter 12 is greater than the second voltage threshold, the voltage Vaux will be greater than the breakdown voltage of the zener diode D4 to turn on, and the NPN transistor Q2 turns on to pull down the bias provided by the bias circuit 152, so that the sensing terminal ISEN of the integrated circuit controller 14 cancels the bias, and the disabling of the fast start function of the integrated circuit controller 14 is terminated to ensure that the driving circuit can start up smoothly and work normally. Conversely, when the output voltage of the converter 12 is lower than the second voltage threshold, the sensing terminal ISEN or the dimming terminal ADIM of the integrated circuit controller 14 is continuously biased. The zener diode D4 is used to configure the switching voltage of the NPN transistor Q2, and also to configure the second voltage threshold.
With continued reference to fig. 3, the comparison circuit 154 further includes a snubber circuit connected between the auxiliary winding L3 and the zener diode D4, which includes a resistor R3, a diode D3, a capacitor C3, and a resistor R4, and the snubber circuit is used to absorb the voltage spike on the auxiliary winding L3 caused by leakage inductance. The comparator circuit 154 further includes a filter component, including a resistor R5 and a capacitor C4, connected between the zener diode D4 and the NPN transistor Q2, for mitigating the effects of noise and leakage current.
In this embodiment, the integrated circuit controller 14 has a connection (not shown) to the voltage Vaux to detect the output voltage. Once the mains is switched on from the input 11 and the output voltage is not established, the integrated circuit controller 14 operates in a fast start/charge mode, which internally sets the output current of the converter 12 at a higher value. At this point the output voltage is still low, so voltage Vaux is low and NPN transistor Q2 is turned off. The output of the linear supply V3 gradually increases to 5V and establishes a bias voltage on the sensing terminal ISEN through resistor R6, diodes D8, D5 and resistor R7. This can pull down the higher output current value provided internally by the integrated circuit controller 14 when the integrated circuit controller 14 is operating in the fast start/charge mode, minimizing the output current of the converter 12, which equivalently disables the fast start/charge mode of the integrated circuit controller 14 to prevent the output current of the converter 12 controlled by the integrated circuit controller 14 from being greater than the UL regulation current. The bias voltage on the sensing terminal ISEN is always present if the LED D6 voltage is continuously clamped low.
The output voltage is further increased and the integrated circuit controller 14 detects, via the aforementioned connection not shown, that the output voltage has been established, the integrated circuit controller 14 will exit the fast start/charge mode, at which time the output current of the drive circuit it controls will meet the requirements of safety regulations. Thus, the bias provided by the disable circuit 15 may be removed. Specifically, the voltage Vaux is high enough to turn on the diode D4, turn on the NPN transistor Q2, pull the bias voltage to ground, and pull down the current from the current sense terminal ISEN, disable the disabling circuit 15, and enable the driving circuit to output normal current. Therefore, the driving circuit for the LED can solve the problem that the output current is large when the LED voltage is not established during starting. And does not affect drive performance under normal conditions.
The above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.
Claims (11)
1. A drive circuit for an LED, comprising
An input (11) for receiving input power;
a converter (12) for power converting the input power;
an output (13) for being connected to the LED to output the converted input power to the LED;
an integrated circuit controller (14) connected to the converter (12) for controlling the power conversion by the converter (12), the integrated circuit controller (14) comprising a function;
characterized in that the drive circuit further comprises:
a disable circuit (15) coupled to the integrated circuit controller (14) for disabling the certain function of the integrated circuit controller (14) when the drive circuit is activated and terminating the disabling of the certain function of the integrated circuit controller (14) after the drive circuit is activated.
2. The driver circuit according to claim 1, further comprising a main PFC circuit (16) for PFC converting the input power and outputting to the LED, wherein the converter (12) is configured to compensate for fluctuation of an output of the main PFC circuit (16), and wherein the output of the main PFC circuit (16) and the converter (12) are connected in series to the LED.
3. A drive circuit according to claim 2, wherein the certain function of the integrated circuit controller (14) comprises a short circuit protection function protecting to switch off the converter (12) when the output voltage of the converter (12) is below a first voltage threshold and the current through the converter (12) is above a first current threshold;
the de-enabling circuit (15) is for preventing the output current of the primary PFC circuit (16) from producing a current in the converter (12) exceeding the first current threshold when the output voltage of the converter (12) has not yet been established to the first voltage threshold to de-enable the short circuit protection function to avoid shutting down the converter (12).
4. The driver circuit according to claim 3, wherein the disable circuit (15) comprises an open switch (Q1) connected in a series circuit of the output of the main PFC circuit (16) and the converter (12), the open switch (Q1) being configured to open the connection between the main PFC circuit (16) and the converter (12) to open the current loop from the main PFC circuit (16) to the converter (12) when the output voltage of the converter (12) has not yet been established to the first voltage threshold, and to close to open the current loop from the main PFC circuit (16) to the converter (12) after the output voltage of the converter (12) has been established to the first voltage threshold such that the output current of the main PFC circuit flows through the LED and the converter (12).
5. The drive circuit of claim 4, wherein the disable circuit (15) further comprises a trigger circuit connected between the output (13) and a control terminal of the open switch for detecting the output voltage and comparing it to the first voltage threshold, the trigger circuit opening the open switch (Q1) when the output voltage of the converter (12) has not yet established the first voltage threshold and closing the open switch (Q1) when the output voltage of the converter (12) has established the first voltage threshold.
6. A drive circuit according to claim 1, wherein the certain function of the integrated circuit controller (14) comprises a quick start function controlling the output current of the converter (12) not to fall below a second current threshold when the output voltage of the converter (12) is below a second voltage threshold, the second current threshold being a maximum value allowed by UL safety regulations.
7. The drive circuit of claim 6, wherein the disable circuit (15) is configured to disable the fast start function to prevent the integrated circuit controller (14) from controlling the output current of the converter (12) to be greater than the second current threshold when the output voltage of the converter (12) has not yet been established to the second voltage threshold, the integrated circuit controller (14) stopping the fast start function after the output voltage of the converter (12) has been established to the second voltage threshold.
8. The drive circuit of claim 7, wherein the integrated circuit controller (14) includes a sense terminal (ISEN) for sensing the output (13) current, and wherein the disable circuit (15) is coupled to the sense terminal for applying a forward bias to the sense terminal to prevent the output current of the converter (12) from being greater than the second current threshold when the output voltage of the converter (12) has not been established to the second voltage threshold, and for removing the forward bias after the output voltage of the converter (12) has been established to the second voltage threshold.
9. The driver circuit of claim 7, wherein the integrated circuit controller (14) includes a dimming terminal (ADIM) for receiving a dimming control signal, and wherein the disable circuit (15) is coupled to the dimming terminal for applying a negative bias to the dimming terminal to prevent the output current of the converter (12) from being greater than the second current threshold when the output voltage of the converter (12) has not yet been established to the second voltage threshold, and for removing the negative bias after the output voltage of the converter (12) has been established to the second voltage threshold.
10. The drive circuit according to claim 8 or 9, wherein the de-enable circuit (15) comprises:
a bias circuit (152) coupled to the integrated circuit controller (14) for providing the bias;
a comparison circuit (154) coupled to the converter (12) and further connected to the bias circuit (152), the comparison circuit (154) configured to detect an output voltage of the converter (12) and compare the detected output voltage to the second voltage threshold, apply the bias to a sense terminal (ISEN) or a dim terminal (ADIM) of the integrated circuit controller (14) when the detected output voltage is below the second voltage threshold, and isolate the bias from the sense terminal (ISEN) or the dim terminal (ADIM) of the integrated circuit controller (14) when the detected output voltage is above the second voltage threshold.
11. An LED lighting device comprising an LED and a driver circuit according to any one of claims 1 to 10, the LED being connected at the output of the driver circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122404015.2U CN216820152U (en) | 2021-09-29 | 2021-09-29 | Driving circuit for LED and LED lighting device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122404015.2U CN216820152U (en) | 2021-09-29 | 2021-09-29 | Driving circuit for LED and LED lighting device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN216820152U true CN216820152U (en) | 2022-06-24 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202122404015.2U Active CN216820152U (en) | 2021-09-29 | 2021-09-29 | Driving circuit for LED and LED lighting device |
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| Country | Link |
|---|---|
| CN (1) | CN216820152U (en) |
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2021
- 2021-09-29 CN CN202122404015.2U patent/CN216820152U/en active Active
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