A constant current driving circuit, a constant current driving device and a lamp

Abstract

The present application belongs to the field of driving technology, and provides a constant current driving circuit, a constant current driving device and a lamp. Alternating current is connected through a rectifier module, and the alternating current is rectified to generate a direct current voltage signal. An electrolytic capacitor is arranged at the output end of the rectifier module to improve the circuit efficiency and eliminate the flicker phenomenon in the direct current voltage signal. The driving module generates a constant current driving signal according to the direct current voltage signal in an intermittent conduction mode, and adjusts the output duty cycle according to the constant current driving signal to maintain the constancy of the current of the constant current driving signal. The electromagnetic suppression module filters out the clutter interference signal in the direct current voltage signal to improve the electromagnetic performance of the circuit, and solves the problem of high driving cost and large driving space size caused by adding an additional anti-flash circuit in the circuit.

Description

Technical Field

[0001] The present application belongs to the field of drive technology, and in particular relates to a constant current drive circuit, a constant current drive device and a lamp. Background Art

[0002] Buck / Boost converter: also known as step-up / step-down converter, is a single-tube non-isolated DC converter whose output voltage can be lower or higher than the input voltage, but the polarity of its output voltage is opposite to the input voltage. Buck / Boost converter can be seen as a Buck converter and a Boost converter connected in series, with the switch tube combined.

[0003] However, the current Boost circuit usually uses a film capacitor for filtering after rectification, and its output will flicker, so it is necessary to add a flash removal circuit, which leads to the problems of high driving cost and large driving space size. Summary of the invention

[0004] The purpose of the present application is to provide a constant current driving circuit, a constant current driving device and a lamp, aiming to solve the problem that the existing boost circuit needs to add a flash removal circuit, resulting in high driving cost and large driving space size.

[0005] A first aspect of an embodiment of the present application provides a constant current driving circuit, the constant current driving circuit comprising:

[0006] A rectifier module, used to receive alternating current and rectify the alternating current to generate a direct current voltage signal;

[0007] An electrolytic capacitor connected to the rectifier module to improve circuit efficiency and eliminate stroboscopic phenomena in the DC voltage signal;

[0008] a driving module connected to the rectifier module, configured to generate a constant current driving signal according to a DC voltage signal in a discontinuous conduction mode, and adjust an output duty cycle according to the constant current driving signal to maintain a constant current of the constant current driving signal; and

[0009] The electromagnetic suppression module is connected to the driving module and is used to filter out the clutter interference signal in the DC voltage signal to improve the electromagnetic performance of the circuit.

[0010] Optionally, the driving module is specifically used to perform current sampling on the constant current driving signal, and adjust a switch duty cycle of the driving module according to the sampling result.

[0011] Optionally, the driving module controls the switch duty cycle according to a preset on-off time relationship, and the preset on-off time relationship is:

[0012] t_off=(V_in-1) / (V_o+1)*t_on;

[0013] Among them, t_off is the off time, t_on is the on time, V_in is the input voltage, and V_o is the output voltage.

[0014] Optionally, the constant current driving circuit further includes:

[0015] The filter module is connected to the drive module and is used to filter the constant current drive signal.

[0016] Optionally, the electromagnetic suppression module includes: a first capacitor, a first diode and a first resistor;

[0017] The first end of the first capacitor and the anode of the first diode are connected to the rectifier module, the second end of the first capacitor is connected to the first end of the first resistor, and the second end of the first resistor and the cathode of the first diode are connected to the output end of the driving module.

[0018] Optionally, the filtering module includes at least one electrolytic capacitor, a first end of the at least one electrolytic capacitor is connected to the driving module, and a second end of the at least one electrolytic capacitor is grounded.

[0019] Optionally, the driving module includes: a first inductor, a second capacitor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a second diode and a constant current driving chip, the first end of the first inductor is connected to the rectifier module, the second end of the first inductor, the first end of the second capacitor, and the anode of the second diode are connected to the output pin of the constant current driving chip, the second end of the second capacitor and the first end of the second resistor are connected, the cathode of the second diode and the second end of the second resistor are connected to the input pin of the constant current driving chip, the current detection pin of the constant current driving chip, the first end of the third resistor and the first end of the fourth resistor are connected, the overvoltage protection pin of the constant current driving chip is connected to the first end of the fifth resistor, and the second end of the third resistor, the second end of the fourth resistor and the second end of the fifth resistor are connected to the output end of the load.

[0020] Optionally, the constant current drive chip includes: a reference voltage signal source, a first switch tube, a second switch tube, an undervoltage lockout unit, a lock restart unit, an overvoltage protection unit, a current detection unit, a current control unit, a conduction time control unit and a drive unit; wherein, the first input end of the overvoltage protection unit constitutes the overvoltage protection pin of the constant current drive chip, the first end of the first switch tube and the first input end of the overvoltage protection unit are connected together to constitute the input pin of the constant current drive chip, the second end of the first switch tube is connected to the undervoltage lockout unit, the control end of the first switch tube is connected to its substrate, the input end of the current detection unit constitutes the current detection pin of the constant current drive chip, and the first input end of the lock restart unit is connected to the The undervoltage lockout unit is connected, the second input end of the lock restart unit is connected to the overvoltage protection unit, the input end of the current detection unit constitutes the current detection pin of the constant current drive chip, the first input end of the current control unit is connected to the reference voltage signal source, the second input end of the current control unit is connected to the current detection unit, the input end of the on-time control unit is connected to the current control unit, the first input end of the drive unit is connected to the on-time control unit, the second input end of the drive unit is connected to the lock restart unit, the first end of the second switch tube is connected to the output pin of the constant current drive chip, and the second end of the second switch tube is connected to the current detection pin of the constant current drive chip.

[0021] Optionally, the overvoltage protection unit is used to sample the output current of the load to generate a reference overvoltage signal, and to generate an overvoltage protection signal when the voltage of the constant current drive signal is greater than the reference overvoltage signal;

[0022] The undervoltage lockout unit is used to perform voltage detection on the input constant current drive signal, and generate an undervoltage protection signal when the voltage of the constant current drive signal is lower than a preset undervoltage threshold;

[0023] The locking and restarting unit is used to lock or restart the driving unit according to the overvoltage protection signal and the undervoltage protection signal.

[0024] Optionally, the current detection unit is used to detect the current of the constant current drive signal and generate a current detection signal;

[0025] The current control unit is used to compare the current detection signal with the reference voltage signal provided by the reference voltage signal source, and generate a current control signal according to the comparison result to control the current size of the constant current drive signal.

[0026] Optionally, the on-time control unit is used to set a switch duty cycle according to the current control signal, and generate a drive control signal based on the switch duty cycle to control the current size of the constant current drive signal.

[0027] Optionally, the driving unit is used to control the on and off of the second switch tube according to the driving control signal.

[0028] Optionally, when the constant current driver chip operates in the intermittent conduction mode, when the second switch tube is turned on, the inductor current output by the driver module increases, and when the second switch tube is turned off, the inductor current output by the driver module decreases, and at the off time t_off = (V_in-1) / (V_o+1)*t_on, the second switch tube is turned on again; wherein t_off is the off time, t_on is the on time, V_in is the input voltage, and V_o is the output voltage.

[0029] A second aspect of an embodiment of the present application provides a constant current driving device, which includes a constant current driving circuit as described in any one of the above items.

[0030] A third aspect of an embodiment of the present application provides a lamp, comprising: a light source module; and a constant current driving circuit as described in any one of the above items, wherein the constant current driving circuit is connected to the light source module.

[0031] The embodiments of the present application provide a constant current drive circuit, a constant current drive device and a lamp, which are connected to alternating current power through a rectifier module, and the alternating current power is rectified to generate a direct current voltage signal. An electrolytic capacitor is arranged at the output end of the rectifier module, and cooperates with the constant current drive circuit to improve the circuit efficiency and eliminate the flicker phenomenon in the direct current voltage signal. The drive module generates a constant current drive signal according to the direct current voltage signal in the intermittent conduction mode, and adjusts the output duty cycle according to the constant current drive signal to maintain the constancy of the current of the constant current drive signal. The electromagnetic suppression module filters out the clutter interference signal in the direct current voltage signal to improve the electromagnetic performance of the circuit, and solves the problem of high driving cost and large driving space size caused by adding an additional anti-flash circuit in the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of a circuit structure of a constant current drive circuit provided in an embodiment of the present application;

[0033] Figure 2 A circuit structure schematic diagram of another constant current drive circuit provided in an embodiment of the present application;

[0034] Figure 3 A schematic diagram of the circuit structure of another constant current drive circuit provided in an embodiment of the present application;

[0035] Figure 4 A schematic diagram of the structure of the constant current driver chip provided in an embodiment of the present application. DETAILED DESCRIPTION

[0036] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0037] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or 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 indirectly connected to the other element.

[0038] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0039] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0040] The present application provides a constant current driving circuit for solving the problems of flicker and low efficiency in the existing driving circuit. Figure 1 As shown, the constant current drive circuit in this embodiment includes: a rectifier module 10, an electrolytic capacitor C3, a drive module 20 and an electromagnetic suppression module 30, wherein the rectifier module 10 is used to access the alternating current and rectify the alternating current to generate a direct current voltage signal; the electrolytic capacitor C3 is connected to the rectifier module 10 to improve the circuit efficiency and eliminate the stroboscopic phenomenon in the direct current voltage signal; the drive module 20 is connected to the rectifier module 10 to generate a constant current drive signal according to the direct current voltage signal in the intermittent conduction mode, and adjust the output duty cycle according to the constant current drive signal to maintain the constant current of the constant current drive signal; the electromagnetic suppression module 30 is connected to the drive module 20 to filter out the clutter interference signal in the direct current voltage signal to improve the electromagnetic performance of the circuit.

[0041] In this embodiment, AC power is connected through the rectifier module 10, and the AC power is rectified to generate a DC voltage signal. An electrolytic capacitor C3 is set at the output end of the rectifier module 10 to improve the circuit efficiency and eliminate the flicker phenomenon in the DC voltage signal. The drive module 20 generates a constant current drive signal according to the DC voltage signal in the intermittent conduction mode, and adjusts the output duty cycle according to the constant current drive signal to maintain the constancy of the current of the constant current drive signal. The electromagnetic suppression module 30 filters out the clutter interference signal in the DC voltage signal to improve the electromagnetic performance of the circuit, thereby solving the problem of high driving cost and large driving space size caused by adding an additional anti-flash circuit in the circuit.

[0042] Specifically, in this embodiment, the rectifier module 10 converts alternating current into pulsating direct current, and a larger-capacity electrolytic capacitor C3 is connected after the rectifier circuit. By replacing the traditional small-capacity film capacitor with the electrolytic capacitor C3, the circuit efficiency is improved. Furthermore, by utilizing the charging and discharging characteristics of the electrolytic capacitor C3, the rectified pulsating direct current voltage is converted into a relatively stable direct current voltage.

[0043] In a practical application embodiment, in order to prevent the power supply voltage of each part of the circuit from changing due to changes in the load 00, an electrolytic capacitor of tens to hundreds of microfarads (for example, 10-500uF) is generally connected to the output end of the rectifier module 10 and the power input end of the load 00. Since large-capacity electrolytic capacitors generally have a certain inductance effect and cannot effectively filter out high-frequency and pulse interference signals, a capacitor with a capacity of 0.001-0.1pF is connected in parallel at both ends to filter out high-frequency and pulse interference.

[0044] In one embodiment, the driving module 20 is specifically used to perform current sampling on the constant current driving signal, and adjust the switch duty cycle of the driving module 20 according to the sampling result.

[0045] In this embodiment, the driving module 20 determines whether the magnitude of the output current is within a constant preset range based on the current sampling result of the constant current driving signal outputted by it, and controls the switch duty cycle inside it accordingly, so as to maintain the output current constant.

[0046] For example, the driving module 20 detects the current flowing out of the load 00 through its current sampling pin to obtain a current detection signal, and compares the current detection signal with the reference voltage signal provided by the reference voltage signal source 21. The current detection threshold can correspond to the average current calculated according to the reference voltage, thereby controlling the duty cycle of the on time and the off time of the driving module 20 in the discontinuous conduction mode (DCM), thereby maintaining the constant output current of the driving module 20.

[0047] In one embodiment, the driving module 20 controls the switch duty cycle according to a preset on-off time relationship, and the preset on-off time relationship is: t_off = (V_in-1) / (V_o+1)*t_on; wherein t_off is the off time, t_on is the on time, V_in is the input voltage, and V_o is the output voltage.

[0048] In this embodiment, the driving module 20 adjusts its output current by controlling the ratio of the on and off time of the internal switch tube (such as MOSFET). Specifically, when the driving module 20 operates in the intermittent conduction mode, when the internal switch tube is turned on, the internal inductor current rises, and when the switch tube is turned off, the internal inductor current of the driving module 20 decreases until t_off = (V_in-1) / (V_o+1)*t_on, and the switch tube is turned on again. In a specific application embodiment, the on-time t_on can be set constant by a timer, and the off-time t_off can be changed to control the duty cycle, thereby reducing the conduction loss and improving the efficiency.

[0049] In one embodiment, see Figure 2 As shown, the constant current driving circuit further includes a filtering module 40, which is connected to the driving module 20 and is used for filtering the constant current driving signal.

[0050] In one embodiment, participating Figure 3 As shown, the electromagnetic suppression module 30 includes: a first capacitor C1, a first diode D1 and a first resistor R1; the first end of the first capacitor C1 and the anode of the first diode D1 are connected to the rectifier module 10, the second end of the first capacitor C1 is connected to the first end of the first resistor R1, and the second end of the first resistor R1 and the cathode of the first diode D1 are connected to the output end of the driving module 20.

[0051] In this embodiment, the first capacitor C1, the first diode D1 and the first resistor R1 form a first-level EMI circuit for eliminating clutter interference in a DC voltage signal to improve the electromagnetic performance of the circuit.

[0052] In one embodiment, see Figure 3 As shown, the rectifier module 10 is a rectifier bridge.

[0053] In this embodiment, the rectifier bridge converts the input 50 / 60HZ voltage of the sine wave into a 100 / 120HZ voltage waveform without a negative half cycle, thereby achieving a full-wave rectification effect.

[0054] In one embodiment, the filter module 40 includes at least one electrolytic capacitor, a first end of the at least one electrolytic capacitor is connected to the driving module 20, and a second end of the at least one electrolytic capacitor is grounded.

[0055] In a specific application embodiment, see Figure 3 As shown, the filter module 40 includes a fourth capacitor C4, a first end of the fourth capacitor C4 is connected to the output end of the driving module 20, and a second end of the fourth capacitor C4 is grounded, wherein the fourth capacitor C4 is an electrolytic capacitor.

[0056] In specific applications, for example, in a switching power supply, the filter module 40 can also be used as an output capacitor to store energy, thereby maintaining a constant voltage. The capacitor selection of the Boost circuit is mainly to control the output ripple within the range specified by the indicator. For the Boost circuit, the impedance of the capacitor and the output current determine the size of the output voltage ripple. The impedance of the capacitor consists of three parts, namely the equivalent series inductance (ESL), the equivalent series resistance (ESR) and the capacitance value (C). In the inductor current continuous mode, the size of the capacitor depends on the output current, the switching frequency and the desired output ripple. When the switch tube inside the driver module 20 is turned on, the output filter capacitor provides 00 current to the entire load.

[0057] In one embodiment, the driving module 20 includes: a first inductor L1, a second capacitor C2, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a second diode D2 and a constant current driving chip U1, the first end of the first inductor L1 is connected to the rectifier module 10, the second end of the first inductor L1, the first end of the second capacitor C2, and the anode of the second diode D2 are connected to the output pin Drain of the constant current driving chip U1, the second end of the second capacitor C2 is connected to the first end of the second resistor R2, the cathode of the second diode D2 and the second end of the second resistor R2 are connected to the input pin Vin of the constant current driving chip U1, the current detection pin ISP of the constant current driving chip U1, the first end of the third resistor R3 and the first end of the fourth resistor R4 are connected, the overvoltage protection pin OVP of the constant current driving chip U1 is connected to the first end of the fifth resistor R5, the second end of the third resistor R3, the second end of the fourth resistor R4 and the second end of the fifth resistor R5 are connected to the output end of the load 00.

[0058] In this embodiment, the second capacitor C2, the second resistor R2 and the second diode D2 form a secondary EMI circuit to filter out interference noise in the constant current drive signal generated by the constant current drive chip U1. Since the input of the drive module 20 is direct current, the current on the first inductor L1 increases linearly at a certain ratio. This ratio is related to the size of its inductance. As the inductor current increases, some energy is stored in the inductor. When the MOS tube inside the constant current driver chip U1 is disconnected, since the current of the inductor remains specific, the current flowing through the inductor will not immediately become 0, but slowly change from the value when charging is completed to 0. The original circuit has been disconnected. Since the inductor can only discharge through the new circuit, that is, the inductor begins to charge the capacitor, the voltage across the capacitor increases, and the voltage is higher than the input voltage. The boost is completed. The boost process is an energy transfer process of the inductor. When charging, the inductor absorbs energy, and when discharging, the inductor releases energy. If the capacitor is large enough, the output end can maintain a continuous current during the discharge process. The on-off process is repeated continuously, and a voltage higher than the input voltage can be obtained at both ends of the capacitor. At the same time, the output current is controlled by controlling the on-time and off-time of the MOS tube inside it. The second diode D2 can prevent the subsequent filter capacitor from discharging to the ground.

[0059] In this embodiment, the constant current driver chip U1 is powered by its output voltage. When the voltage of its input pin Vin is higher than the start voltage, the constant current driver chip U1 starts to supply power. When the voltage of the input pin Vin is lower than the start voltage, the chip starts undervoltage protection, and the chip is locked until it returns to normal and starts again. Furthermore, the chip detects the current through the current detection pin ISP pin, and compares it with the average current calculated by the reference voltage to maintain the constant output current. Specifically, by controlling the constant on-time t_on, changing the off-time t_off, and controlling the duty cycle, the conduction loss is reduced and the efficiency is improved.

[0060] In a specific application embodiment, the constant current driver chip U1 operates in a discontinuous conduction mode. When the internal MOSFET is turned on, the inductor current in the driver module 20 increases. When the MOSFET is turned off, the inductor current in the circuit decreases and eventually returns to zero until t_off = (V_in-1) / (V_o+1)*t_on, when the MOSFET is turned on again.

[0061] In a specific application embodiment, the constant current driver chip U1 has an overvoltage protection function. When its output voltage is higher than the OVP voltage set by the connection mode of its overvoltage protection pin OVP, the chip is locked until it returns to normal and starts again.

[0062] Specifically, in this embodiment, the fifth resistor R5 is connected to the overvoltage protection pin OVP of the constant current driver chip U1. Since the load 00 outputs current, the fifth resistor R5 is used to divide the voltage to provide an OVP voltage as a reference voltage. The voltage of the input pin Vin of the constant current driver chip U1 is compared with the reference voltage to avoid excessive voltage at its input pin, and the reference voltage can change with the output current of the load 00 to achieve dynamic overvoltage protection.

[0063] In one embodiment, the third resistor R3 and the fourth resistor R4 divide the current output by the load 00 to obtain a divided voltage signal, and the divided voltage signal is input to the constant current driver chip U1 by the current detection pin ISP of the constant current driver chip U1. Specifically, since the resistance values ​​of the third resistor R3 and the fourth resistor R4 are fixed, the divided voltage signal corresponds to the output current of the load, and the constant current driver chip U1 compares the divided voltage signal with the reference voltage signal provided by the reference voltage signal source set internally, and controls its output current according to the comparison result, wherein the reference voltage signal source can correspond to the highest current threshold or rated power of the constant current driver chip U1, so as to avoid damage to the chip due to excessive power caused by the need to maintain constant current output when the load of the constant current driver chip U1 increases.

[0064] In one embodiment, see Figure 4 As shown, the constant current driving chip U1 includes: a reference voltage signal source 21, a first switch tube Q1, a second switch tube Q2, an undervoltage lockout unit 22, a lock restart unit 23, an overvoltage protection unit 24, a current detection unit 25, a current control unit 26, a conduction time control unit 27 and a driving unit 28.

[0065] Specifically, the overvoltage protection unit 24 is used to sample the output current of the load to generate a reference overvoltage signal, and to generate an overvoltage protection signal when the voltage of the constant current drive signal is greater than the reference overvoltage signal; wherein the first input end of the overvoltage protection unit 24 constitutes the overvoltage protection pin OVP of the constant current drive chip U1, and the first end of the first switch tube Q1 and the first input end of the overvoltage protection unit 24 are connected together to constitute the input pin Vin of the constant current drive chip U1; the undervoltage lockout unit 22 is used to perform voltage detection on the input constant current drive signal, and to generate an undervoltage protection signal when the voltage of the constant current drive signal is lower than a preset undervoltage threshold; wherein the second end of the first switch tube Q1 is connected to the undervoltage lockout unit 22, and the control end of the first switch tube Q1 is connected to its substrate; the locking and restarting unit 23 is used to lock or restart the drive unit 28 according to the overvoltage protection signal and the undervoltage protection signal; the first input end of the locking and restarting unit 23 is connected to the undervoltage lockout unit 22, and the second input end of the locking and restarting unit 23 is connected to the overvoltage protection unit 24; the current detection unit 25 is used to detect the constant current drive signal The input end of the current detection unit 25 constitutes the current detection pin ISP of the constant current driving chip U1; the current control unit 26 is used to compare the current detection signal with the reference voltage signal provided by the reference voltage signal source 21, and generate a current control signal according to the comparison result; the first input end of the current control unit 26 is connected to the reference voltage signal source 21, and the second input end of the current control unit 26 is connected to the current detection unit 25; the on-time control unit 27 is used to set the switch duty ratio according to the current control signal and generate a drive control signal; the input end of the on-time control unit 27 is connected to the current control unit 26; the driving unit 28 is used to control the on and off of the second switch tube Q2 according to the drive control signal; wherein the first input end of the driving unit 28 is connected to the on-time control unit 27, the second input end of the driving unit 28 is connected to the lock restart unit 23, the first end of the second switch tube Q2 is connected to the output pin of the constant current driving chip U1, and the second end of the second switch tube Q2 is connected to the current detection pin of the constant current driving chip U1.

[0066] In this embodiment, the undervoltage lockout unit 22 is used to perform voltage detection on the voltage of the input pin Vin of the constant current driver chip U1. When the voltage of its input pin Vin is lower than the preset undervoltage threshold (i.e., the starting voltage), the chip triggers the undervoltage lockout function and sends an undervoltage protection signal to the lock and restart unit 23 to lock the drive unit 28 and stop running, and restart after the voltage of the input pin Vin is restored.

[0067] In this embodiment, the overvoltage protection unit 24 is used to determine the OVP voltage (i.e., the voltage of a preset reference overvoltage signal) according to the connection method of the overvoltage protection pin OVP of the constant current driver chip U1. At the same time, the overvoltage protection unit 24 receives the constant current drive signal of the input pin Vin, and generates an overvoltage protection signal when the voltage of the constant current drive signal is greater than the reference overvoltage signal and sends it to the lock and restart unit 23, so as to lock the chip and restart it after a preset time.

[0068] The current detection unit 25 detects the output current of its load 00 by detecting the current of the current detection pin ISP, generates a current detection signal, and sends it to the current control unit 26. The current control unit 26 compares the current detection signal received by feedback with the reference voltage signal provided by the reference voltage signal source 21, and generates a current control signal according to the comparison result to adjust the output current of the constant current driver chip U1. Specifically, the on-time control unit 27 sets the switch duty cycle according to the current control signal, and generates a drive control signal to limit the on-time ton to ensure that the chip works in the intermittent conduction mode, and the drive unit 28 generates a corresponding pulse width modulation signal to drive the second switch tube Q2 to alternately turn on and off, thereby maintaining the constant output current of the constant current driver chip U1.

[0069] In one embodiment, the constant current driver chip U1 further includes a power supply unit 29 for supplying power to other functional units in the chip. Specifically, the constant current driver chip U1 can draw power according to its output voltage and perform voltage conversion to generate multiple voltages to supply power to other functional units.

[0070] In one embodiment, the first switch tube Q1 and the second switch tube Q2 are both N-type MOS tubes.

[0071] In a specific application embodiment, when the constant current driver chip U1 operates in the intermittent conduction mode, when the second switch tube Q2 is turned on, the inductor current in the driver module 20 increases, and when the second switch tube Q2 is turned off, the inductor current in the circuit decreases and eventually returns to zero, until t_off = (V_in-1) / (V_o+1)*t_on, the MOSFET is turned on again.

[0072] An embodiment of the present application further provides a constant current driving device, which includes a constant current driving circuit as described above.

[0073] An embodiment of the present application further provides a lamp, comprising: a light source module; and a constant current driving circuit as described in any one of the above items, wherein the constant current driving circuit is connected to the light source module.

[0074] The embodiments of the present application provide a constant current drive circuit, a constant current drive device and a lamp, which are connected to alternating current power through a rectifier module, and the alternating current power is rectified to generate a direct current voltage signal. An electrolytic capacitor is arranged at the output end of the rectifier module to improve the circuit efficiency and eliminate the flicker phenomenon in the direct current voltage signal. The drive module generates a constant current drive signal according to the direct current voltage signal in an intermittent conduction mode, and adjusts the output duty cycle according to the constant current drive signal to maintain the constancy of the current of the constant current drive signal. The electromagnetic suppression module filters out the clutter interference signal in the direct current voltage signal to improve the electromagnetic performance of the circuit, thereby solving the problem of high drive cost and large drive space size caused by adding an additional anti-flash circuit in the circuit.

[0075] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0076] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0077] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0078] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0079] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A constant current driving circuit, characterized in that: The constant current driving circuit comprises: A rectifier module, used to receive alternating current and rectify the alternating current to generate a direct current voltage signal; An electrolytic capacitor connected to the rectifier module to improve circuit efficiency and eliminate stroboscopic phenomena in the DC voltage signal; a driving module connected to the rectifier module, configured to generate a constant current driving signal according to a DC voltage signal in a discontinuous conduction mode, and adjust an output duty cycle according to the constant current driving signal to maintain a constant current of the constant current driving signal; and An electromagnetic suppression module, connected to the driving module, for filtering out clutter interference signals in the DC voltage signal to improve the electromagnetic performance of the circuit; The driving module includes: a first inductor, a second capacitor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a second diode and a constant current driving chip; The first end of the first inductor is connected to the rectifier module, the second end of the first inductor, the first end of the second capacitor, and the anode of the second diode are connected to the output pin of the constant current drive chip, the second end of the second capacitor is connected to the first end of the second resistor, the cathode of the second diode and the second end of the second resistor are connected to the input pin of the constant current drive chip, the current detection pin of the constant current drive chip, the first end of the third resistor and the first end of the fourth resistor are connected, the overvoltage protection pin of the constant current drive chip is connected to the first end of the fifth resistor, and the second end of the third resistor, the second end of the fourth resistor and the second end of the fifth resistor are connected to the output end of the load; The constant current driving chip comprises: a reference voltage signal source, a first switch tube, a second switch tube, an undervoltage lockout unit, a lock restart unit, an overvoltage protection unit, a current detection unit, a current control unit, a conduction time control unit and a driving unit; The overvoltage protection unit is used to sample the output current of the load to generate a reference overvoltage signal, and to generate an overvoltage protection signal when the voltage of the constant current drive signal is greater than the reference overvoltage signal; wherein the first input end of the overvoltage protection unit constitutes the overvoltage protection pin of the constant current drive chip, and the first end of the first switch tube and the first input end of the overvoltage protection unit are connected together to form the input pin of the constant current drive chip; the undervoltage lockout unit is used to perform voltage detection on the input constant current drive signal, and to generate an undervoltage protection signal when the voltage of the constant current drive signal is lower than a preset undervoltage threshold; wherein the second end of the first switch tube is connected to the undervoltage lockout unit, and the control end of the first switch tube is connected to its substrate; the lock restart unit is used to lock or restart the drive unit according to the overvoltage protection signal and the undervoltage protection signal; the first input end of the lock restart unit is connected to the undervoltage lockout unit, and the second input end of the lock restart unit is connected to the overvoltage protection unit; the current detection unit is used to detect the constant current drive signal The invention relates to a method for detecting a current of a constant current driving chip and generating a current detection signal; the input end of the current detection unit constitutes a current detection pin of the constant current driving chip; a current control unit is used to compare the current detection signal with a reference voltage signal provided by a reference voltage signal source, and generate a current control signal according to the comparison result; the first input end of the current control unit is connected to the reference voltage signal source, and the second input end of the current control unit is connected to the current detection unit; a conduction time control unit is used to set the switch duty cycle according to the current control signal and generate a drive control signal; the input end of the conduction time control unit is connected to the current control unit; a driving unit is used to control the conduction and shutdown of the second switch tube according to the drive control signal; wherein the first input end of the driving unit is connected to the conduction time control unit, the second input end of the driving unit is connected to the lock restart unit, the first end of the second switch tube is connected to the output pin of the constant current driving chip, and the second end of the second switch tube is connected to the current detection pin of the constant current driving chip.

2. The constant current driving circuit according to claim 1, characterized in that: The driving module is specifically used to perform current sampling on the constant current driving signal, and adjust the switch duty cycle of the driving module according to the sampling result.

3. The constant current driving circuit according to claim 2, characterized in that: The driving module controls the switch duty cycle according to a preset on-off time relationship, and the preset on-off time relationship is: t_off=(V_in-1) / (V_o+1)*t_on; Among them, t_off is the off time, t_on is the on time, V_in is the input voltage, and V_o is the output voltage.

4. The constant current driving circuit according to claim 1, characterized in that: The constant current driving circuit also includes: The filter module is connected to the drive module and is used to filter the constant current drive signal.

5. The constant current driving circuit according to claim 4, characterized in that: The filter module comprises at least one electrolytic capacitor, a first end of the at least one electrolytic capacitor is connected to the driving module, and a second end of the at least one electrolytic capacitor is grounded.

6. The constant current driving circuit according to claim 1, characterized in that: The electromagnetic suppression module includes: a first capacitor, a first diode and a first resistor; The first end of the first capacitor and the anode of the first diode are connected to the rectifier module, the second end of the first capacitor is connected to the first end of the first resistor, and the second end of the first resistor and the cathode of the first diode are connected to the output end of the driving module.

7. The constant current driving circuit according to claim 1, characterized in that: The current detection unit is used to detect the current of the constant current driving signal and generate a current detection signal; The current control unit is used to compare the current detection signal with the reference voltage signal provided by the reference voltage signal source, and generate a current control signal according to the comparison result to control the current size of the constant current drive signal.

8. The constant current driving circuit according to claim 7, characterized in that: The on-time control unit is used to set a switch duty cycle according to the current control signal, and generate a drive control signal based on the switch duty cycle to control the current size of the constant current drive signal.

9. The constant current driving circuit according to claim 8, characterized in that: The driving unit is used to control the on and off of the second switch tube according to the driving control signal.

10. The constant current driving circuit according to claim 1, characterized in that: When the constant current driver chip operates in the intermittent conduction mode, when the second switch tube is turned on, the inductor current output by the driver module increases, and when the second switch tube is turned off, the inductor current output by the driver module decreases, and when the off time t_off = (V_in-1) / (V_o+1)*t_on, the second switch tube is turned on again; wherein t_off is the off time, t_on is the on time, V_in is the input voltage, and V_o is the output voltage.

11. A constant current driving device, characterized in that: The constant current driving device comprises a constant current driving circuit as described in any one of claims 1-10.

12. A lamp, characterized in that: include: Light source module; And the constant current driving circuit as described in any one of claims 1 to 10, wherein the constant current driving circuit is connected to the light source module.

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