Switching power supply and its control circuit

Abstract

A switching power supply and its control circuit are disclosed. The control circuit includes a power supply module that generates a power supply current based on a DC bus voltage; a bias module that generates a first current for powering a drive module and a second current for powering a standby module based on the power supply current and a standby control signal; a standby module that generates a standby control signal based on a modulation signal and a reference signal; and a drive module that generates a drive signal based on the modulation signal and the standby control signal. The drive signal is used to control the on / off state of a power switching transistor. When the standby control signal is active, the drive signal keeps the power switching transistor in an off state. This invention uses a multiplexed modulation signal as a standby enable signal for standby control, reducing the need for external circuitry matching the standby enable signal and lowering the complexity and cost of implementing the switching power supply.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit technology, and more specifically, to a switching power supply and its control circuit. Background Technology

[0002] With increasing awareness of energy conservation and environmental protection, the requirements for energy consumption have become more stringent. More and more electronic products now require low-power standby operation, leading to a growing demand for low-power standby circuits that can be added to electronic products to shut down their driver modules without disconnecting the main power input of the driver modules.

[0003] Low-power standby circuits use only a very small external current (smaller than that typically required for external relays) to operate the disconnect function, shutting down some or all of the control circuitry inside the drive module, thereby achieving low standby power consumption.

[0004] Existing low-power standby implementation methods are generally divided into system-level and chip-level. The basic principle of implementation is: by receiving the standby enable signal, processing it, and then shutting down most of the power-consuming paths inside the driver module, low-power standby is achieved.

[0005] In many industrial, commercial, or residential lighting systems that utilize light-emitting diodes (LEDs), low-current interfaces are used to shut down the driver module, enabling low-power standby. By using low-current switching, wear and tear on the relay mechanism is avoided, and less power can be used compared to conventional standby voltage circuits.

[0006] The standby enable signal for system-level low-power standby implementations needs to be kept active by adding external circuitry and a low-voltage power supply. Correspondingly, most existing chip-level low-power standby implementations increase application complexity and have higher power consumption during standby because they require independent standby enable signals. Summary of the Invention

[0007] In view of the above problems, the purpose of this invention is to provide a switching power supply and its control circuit, which reduces power consumption in standby mode by adjusting the current, simplifies the complexity of standby control, and improves the standby control efficiency of the system.

[0008] According to one aspect of the present invention, a control circuit for a switching power supply is provided, comprising:

[0009] The power supply module generates power supply current based on the DC bus voltage;

[0010] The bias module is used to generate a first current and a second current based on the power supply current and the standby control signal;

[0011] The standby module is used to generate standby control signals based on the modulation signal and the reference signal;

[0012] A drive module is used to generate a drive signal based on a modulation signal and a standby control signal, wherein the drive signal is used to control the on and off of the power switching transistor;

[0013] Wherein, the first current supplies power to the drive module, and the second current supplies power to the standby module;

[0014] When the standby control signal is at an active level, the drive signal keeps the power switch in the off state.

[0015] Optionally, the modulation signal is an analog dimming signal or a pulse width dimming signal.

[0016] Optionally, when the modulation signal is an analog dimming signal, the standby module includes:

[0017] The comparator compares the voltage value of the modulated signal with the voltage value of the reference signal and outputs a standby control signal.

[0018] Optionally, when the voltage value of the modulation signal is less than the voltage value of the reference signal, the standby control signal is at an active level;

[0019] When the voltage value of the modulation signal is greater than the voltage value of the reference signal, the standby control signal is at an invalid level.

[0020] Optionally, the standby module includes:

[0021] The comparator compares the voltage value of the modulated signal with the voltage value of the reference signal and outputs a comparison signal.

[0022] The counting unit generates a standby control signal based on the level state of the comparison signal and the preset invalid level duration.

[0023] Optionally, when the modulated signal is less than the reference signal, the comparison signal is at an active level; when the modulated signal is greater than the reference signal, the comparison signal is at an inactive level.

[0024] Optionally, when the effective level duration of the comparison signal is greater than the preset effective level duration, the standby control signal is at an effective level;

[0025] When the effective level of the comparison signal is less than the preset effective level duration and the comparison signal is invalid, the standby control signal is invalid.

[0026] Optionally, the bias module further adjusts the magnitude of the first current according to the standby control signal.

[0027] Optionally, the bias module further adjusts the magnitude of the second current according to the standby control signal.

[0028] Optionally, the bias module includes:

[0029] The input unit is used to generate a bias current based on the supply current.

[0030] A biasing unit is used to generate a first current and a second current based on the bias current;

[0031] The output unit is used to output the first current and the second current to the drive module and the standby module, respectively;

[0032] A switching unit is used to control the conduction and / or cutoff of the first path and / or the second path according to a standby control signal;

[0033] The first path is the path between the input unit and the bias unit; the second path is the path between the output unit and the driver module and / or the path between the output unit and the standby module.

[0034] Optionally, the input unit includes:

[0035] The first current mirror unit mirrors and outputs the power supply current to the bias unit.

[0036] The second current mirror unit mirrors the output of the power supply current.

[0037] The switching unit includes a first switch connected between the second current mirror unit and the bias unit. The first switch is turned on and off according to the standby control signal.

[0038] Optionally, the output unit includes:

[0039] The third current mirror unit outputs the first current mirror image to the drive module;

[0040] The fourth current mirror unit outputs the second current mirror to the standby module.

[0041] Optionally, when the standby control signal is at an active level, the first switch is turned off; when the standby control signal is at an inactive level, the first switch is turned on.

[0042] Optionally, the input unit includes:

[0043] The fifth current mirror unit mirrors the power supply current and outputs it to the bias unit.

[0044] Optionally, the output unit includes:

[0045] The sixth current mirror unit outputs the first current mirror image to the drive module;

[0046] The seventh current mirror unit mirrors and outputs the first current.

[0047] The eighth current mirror unit outputs the second current image to the standby module;

[0048] The ninth current mirror unit outputs the second current mirror.

[0049] Optionally, the switching unit includes a third switch connected between the seventh current mirror unit and the driving module; wherein the third switch is turned on and off according to the standby control signal.

[0050] Optionally, when the standby control signal is at an active level, the third switch is turned off; when the standby control signal is at an inactive level, the third switch is turned on.

[0051] Optionally, the switching unit includes:

[0052] The third switch is connected between the seventh current mirror unit and the drive module;

[0053] A second switch is connected between the ninth current mirror unit and the standby module;

[0054] The second switch and the third switch are turned on and off according to the standby control signal.

[0055] Optionally, when the standby control signal is at an active level, the second switch and the third switch are turned off; when the standby control signal is at an inactive level, the second switch and the third switch are turned on.

[0056] According to another aspect of the present invention, a switching power supply is provided, comprising:

[0057] A rectifier bridge converts AC power into DC bus voltage.

[0058] A power conversion circuit converts the DC bus voltage into a DC output voltage.

[0059] Control circuit, including:

[0060] The power supply module generates power supply current based on the DC bus voltage;

[0061] The bias module is used to generate a first current and a second current based on the power supply current and the standby control signal;

[0062] The standby module is used to generate standby control signals based on the modulation signal and the reference signal;

[0063] A drive module is used to generate a drive signal based on a modulation signal and a standby control signal, wherein the drive signal is used to control the on and off of the power switching transistor;

[0064] Wherein, the first current supplies power to the drive module, and the second current supplies power to the standby module;

[0065] When the standby control signal is at an active level, the drive signal keeps the power switch in the off state.

[0066] Optionally, the modulation signal is an analog dimming signal or a pulse width dimming signal.

[0067] Optionally, when the modulation signal is an analog dimming signal, the standby module includes:

[0068] The comparator compares the voltage value of the modulated signal with the voltage value of the reference signal and outputs a standby control signal.

[0069] Optionally, when the voltage value of the modulation signal is less than the voltage value of the reference signal, the standby control signal is at an active level;

[0070] When the voltage value of the modulation signal is greater than the voltage value of the reference signal, the standby control signal is at an invalid level.

[0071] Optionally, the standby module includes:

[0072] The comparator compares the voltage value of the modulated signal with the voltage value of the reference signal and outputs a comparison signal.

[0073] The counting unit generates a standby control signal based on the level state of the comparison signal and the preset invalid level duration.

[0074] Optionally, when the modulated signal is less than the reference signal, the comparison signal is at an active level; when the modulated signal is greater than the reference signal, the comparison signal is at an inactive level.

[0075] Optionally, when the effective level duration of the comparison signal is greater than the preset effective level duration, the standby control signal is at an effective level;

[0076] When the effective level of the comparison signal is less than the preset effective level duration and the comparison signal is invalid, the standby control signal is invalid.

[0077] Optionally, the bias module further adjusts the magnitude of the first current according to the standby control signal.

[0078] Optionally, the bias module further adjusts the magnitude of the second current according to the standby control signal.

[0079] Optionally, the bias module includes:

[0080] The input unit is used to generate a bias current based on the supply current.

[0081] A biasing unit is used to generate a first current and a second current based on the bias current;

[0082] The output unit is used to output the first current and the second current to the drive module and the standby module, respectively;

[0083] A switching unit is used to control the conduction and cutoff of the first path or the second path according to the standby control signal;

[0084] The first path is the path between the input unit and the bias unit; the second path is the path between the output unit and the driver module and / or the path between the output unit and the standby module.

[0085] Optionally, the input unit includes:

[0086] The first current mirror unit mirrors and outputs the power supply current to the bias unit.

[0087] The second current mirror unit mirrors the output of the power supply current.

[0088] The switching unit includes a first switch connected between the second current mirror unit and the bias unit. The first switch is turned on and off according to the standby control signal.

[0089] Optionally, the output unit includes:

[0090] The third current mirror unit outputs the first current mirror image to the drive module;

[0091] The fourth current mirror unit outputs the second current mirror to the standby module.

[0092] Optionally, when the standby control signal is at an active level, the first switch is turned off; when the standby control signal is at an inactive level, the first switch is turned on.

[0093] Optionally, the input unit includes:

[0094] The fifth current mirror unit mirrors the power supply current and outputs it to the bias unit.

[0095] Optionally, the output unit includes:

[0096] The sixth current mirror unit outputs the first current mirror image to the drive module;

[0097] The seventh current mirror unit mirrors and outputs the first current.

[0098] The eighth current mirror unit outputs the second current image to the standby module;

[0099] The ninth current mirror unit outputs the second current mirror.

[0100] Optionally, the switching unit includes a third switch connected between the seventh current mirror unit and the driving module; wherein the third switch is turned on and off according to the standby control signal.

[0101] Optionally, when the standby control signal is at an active level, the third switch is turned off; when the standby control signal is at an inactive level, the third switch is turned on.

[0102] Optionally, the switching unit includes:

[0103] The third switch is connected between the seventh current mirror unit and the drive module;

[0104] A second switch is connected between the ninth current mirror unit and the standby module;

[0105] The second switch and the third switch are turned on and off according to the standby control signal.

[0106] Optionally, when the standby control signal is at an active level, the second switch and the third switch are turned off; when the standby control signal is at an inactive level, the second switch and the third switch are turned on.

[0107] The control circuit of the switching power supply provided by the present invention reuses the modulation signal as the standby enable signal of the standby module and provides the standby control signal according to the modulation signal. There is no need for a separate standby enable signal, which can reduce the setting of peripheral circuits that match the standby enable signal, reduce the implementation complexity of the switching power supply, and reduce costs.

[0108] Furthermore, a first current and a second current are provided through a bias module to supply power to the standby module and the drive module, respectively. The magnitudes of the first current and the second current are adjusted according to the standby module to regulate the power consumption of the standby module and the drive module.

[0109] Furthermore, the standby module includes a comparator and a counting unit. The comparator provides a comparison signal based on the comparison of the modulation signal and the reference voltage signal, and the counting unit provides a standby control signal based on the comparison signal and a preset invalid level duration.

[0110] Furthermore, when the effective level duration of the comparison signal is greater than a preset effective level duration, the standby control signal is at an effective level; when the effective level of the comparison signal is less than the preset effective level duration and the comparison signal is at an invalid level, the standby control signal is at an invalid level. This reduces interference from modulation signal fluctuations, provides a reliable standby control signal, avoids false triggering of standby control caused by modulation signal fluctuations, and improves system reliability. Attached Figure Description

[0111] The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0112] Figure 1 A schematic diagram of a switching power supply according to the prior art is shown;

[0113] Figure 2 A partial structural schematic diagram of a switching power supply according to an embodiment of the present invention is shown;

[0114] Figure 3A and Figure 3B It shows that according to Figure 2 The following is a partial signal timing diagram of the switching power supply;

[0115] Figure 4A and Figure 4B A schematic diagram of the standby module of a switching power supply according to another embodiment of the present invention and a timing diagram of some of its signals are shown respectively.

[0116] Figure 5 A schematic diagram of the bias module of a switching power supply according to a first embodiment of the present invention is shown;

[0117] Figure 6 A schematic diagram of the bias module of a switching power supply according to a second embodiment of the present invention is shown;

[0118] Figure 7 A schematic diagram of the bias module of a switching power supply according to a third embodiment of the present invention is shown. Detailed Implementation

[0119] Various embodiments of the invention will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements are indicated by the same or similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale.

[0120] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0121] Figure 1 A schematic diagram of a switching power supply in the prior art is shown. For example... Figure 1 As shown, the switching power supply 100 includes a rectifier bridge 101, an input holding capacitor Cin, a power conversion circuit 102, and a control circuit 103.

[0122] The rectifier bridge 101 converts the AC power supply Vac into a DC bus voltage HV. The input holding capacitor Cin is connected between the output terminal of the rectifier bridge 101 and ground to stabilize the output of the DC bus voltage HV. The power conversion circuit 102 converts the DC bus voltage Vin into a DC output voltage Vo and provides this DC output voltage Vo to the load resistor R1. Here, the load resistor R1 represents the load of the switching power supply 100, for example, a string of LEDs.

[0123] The two input terminals of rectifier bridge 101 receive an AC input voltage Vac from an external AC power supply. An input holding capacitor Cin is connected between the two output terminals of rectifier bridge 101, thereby providing a DC input voltage Vin. Rectifier bridge 101 includes, for example, diodes D1 to D4. Diodes D1 and D2 are connected in series in forward direction between the positive and negative output terminals of the AC power supply Vac, and diodes D3 and D4 are connected in series in forward direction between the positive and negative output terminals of the AC power supply Vac. The midpoint between diodes D1 and D2 is grounded, and the midpoint between diodes D3 and D4 provides a DC bus voltage Vin.

[0124] The power conversion circuit 102 includes a freewheeling diode D0, an inductor L1, a power switch M0, a sampling resistor Rs, and an output holding capacitor Co. The freewheeling diode D0, the power switch M0, and the sampling resistor Rs are connected in series between the high-potential terminal of the input holding capacitor Cin and the ground terminal. The output holding capacitor Co and the inductor L are connected in series between the two ends of the freewheeling diode D0. A DC output voltage Vo is output across the output holding capacitor Co. A load resistor R1 is connected in parallel between the two ends of the output holding capacitor Co.

[0125] The switching power supply control circuit 103 includes a standby module 104 and a drive module 105. The standby module 104 receives an external standby enable signal En-sb and converts it into a standby control signal Ctrl-sb. The drive module 105 generates a drive signal Vg based on the standby control signal Ctrl-sb, the current sampling signal VCS, and the modulation signal DIM. This drive signal Vg controls the on / off state of the power switch M0. When the standby control signal Ctrl-sb is at an active level, the drive signal Vg keeps the power switch M0 in the off state, thereby shutting down the power conversion circuit 102 and putting the switching power supply 100 into standby mode. When the standby control signal Ctrl-sb is at an inactive level, the drive signal Vg can control the on / off state of the power switch M0, thereby allowing the power conversion circuit 102 to operate normally and putting the switching power supply 100 into normal operating mode. The modulation signal DIM is, for example, an analog dimming signal or a pulse width modulation (PWM) signal.

[0126] The power supply current of the control circuit 103 is provided by an external power source or by the DC bus voltage Vin.

[0127] In the existing switching power supply 100, the standby module 104 converts the independent standby enable signal En-sb into a standby control signal Ctrl-sb and provides it to the drive module 105 to achieve standby control. The standby enable signal En-sb requires supporting peripheral circuits and a low-voltage power supply to maintain its activation, resulting in high application costs. Furthermore, its power consumption remains high during the shutdown period of the drive module 105.

[0128] Figure 2 A partial structural schematic diagram of a switching power supply according to an embodiment of the present invention is shown. The difference between the switching power supply 200 of the present invention and the prior art switching power supply 100 lies in the control circuit 203 section; the identical power conversion circuit 202 section and other identical parts will not be described further.

[0129] Reference Figure 2 The control circuit 203 of the switching power supply 200 in this embodiment of the invention includes a power supply module 210, a bias module 220, a drive module 230, and a standby module 240.

[0130] The power supply module 210 is used to provide power supply current to the bias module 220 according to the DC bus voltage Vin. In this embodiment, the power supply current is a constant current.

[0131] The bias module 220 provides a first current and a second current to the drive module 230 and the standby module 240 respectively according to the power supply current.

[0132] The drive module 230 provides the drive signal Vg based on the modulation signal DIM and the current sampling signal VCS.

[0133] The modulation signal DIM is a dimming signal output by an external controller. The reference signal Vref is selected as a relatively small voltage value, such as 10% of the maximum amplitude of the modulation signal DIM. When the dimming signal becomes smaller and less than the preset reference value Vref, the system starts to determine whether to enter standby mode. The value of the reference signal Vref can be adjusted according to the actual application.

[0134] The standby module 240 also provides a standby control signal DJ according to the modulation signal DIM. The standby control signal DJ is provided to the bias module 220 and the drive module 230. When the standby control signal DJ is valid, the drive module 230 is controlled to output an invalid drive signal (i.e., the drive signal Vg is invalid and the power switch M0 is in the off state). The bias module 220 is controlled to reduce the current output power, thereby reducing the power of the first current and the second current received by the drive module 230 and the standby module 240, and reducing the power consumption of the drive module 230 and the standby module 240 in standby mode.

[0135] In this embodiment, the standby module 240 includes a comparator 241 and a counting unit 242.

[0136] The comparator 241 is used to generate a comparison signal CS based on the modulation signal DIM and the reference voltage Vref.

[0137] Figure 3A and Figure 3B It shows that according to Figure 2 The diagram shows a partial signal timing diagram of the switching power supply.

[0138] In this embodiment, see Figure 3A The modulation signal DIM is an analog dimming signal. When the voltage value of the modulation signal DIM is less than the reference voltage Vref, the comparison signal CS is in an active state. When the voltage value of the modulation signal DIM is greater than the reference voltage Vref, the comparison signal CS is in an inactive state.

[0139] In this embodiment, the non-inverting input of comparator 241 is connected to the modulation signal DIM, and the inverting input is connected to the reference voltage Vref. When the effective level of the comparison signal CS is low, the voltage value of the modulation signal DIM is less than the reference voltage Vref of the reference signal. When the ineffective level is high, the voltage value of the modulation signal DIM is greater than the reference voltage Vref of the reference signal.

[0140] The counting unit 242 is connected to the output of the comparator 241 and is used to generate a standby control signal DJ based on the comparison signal CS and the preset effective level duration.

[0141] In this embodiment, see Figure 3B When the modulation signal DIM is a pulse width modulation signal, i.e., a square wave signal, and the voltage of the modulation signal DIM is less than the reference voltage Vref, the comparison signal VS is in an active level state. When the active level state is maintained for a time longer than the preset active level maintenance time (t1 to t2 time), the standby control signal DJ flips to an active level. When the voltage of the modulation signal DIM is greater than the reference voltage Vref, the counting unit 242 is cleared, and the standby control signal DJ directly flips to an inactive level, which in this embodiment is a flip from low level to high level.

[0142] The counting unit 242 counts once every counting time (e.g., synchronized with the period of the modulation signal DIM), and counts once when the comparison signal CS is in an invalid state, incrementing the count value by 1. When the comparison signal CS is in an active state, the count value is cleared. Correspondingly, in normal working mode, the count value of the counting unit 242 repeatedly executes between incrementing and clearing, with a maximum count value of 1, providing an invalid standby control signal DJ.

[0143] When the modulation signal DIM is an analog dimming signal, refer to Figure 3A After time t0, when the voltage value of the modulation signal DIM is greater than the reference voltage Vref, the standby control signal DJ flips to a high level, confirming the working control, providing an invalid standby control signal DJ, controlling the switching power supply 200 to enter the working mode, and the duty cycle of the drive signal Vg changes with the modulation signal DIM.

[0144] After time t1, the voltage value of the modulation signal DIM is less than the reference voltage Vref, the comparison signal CS remains in an invalid low level state, the counting unit 242 starts to count continuously, and by time t2, the count value (number of consecutive counts) reaches the counting threshold, the standby control signal DJ flips to a low level, confirming standby control, providing a valid standby control signal DJ, controlling the switching power supply 200 to enter standby mode, stopping the supply of the first current I1, and the drive module 230 enters a low power consumption state.

[0145] When the modulation signal DIM is a pulse width modulation signal, refer to Figure 3BAfter time t0, the modulation signal DIM starts to provide square wave pulses. The high voltage of the pulse is greater than the reference voltage Vref. The standby control signal DJ flips to a high level, confirming the working control. An invalid standby control signal DJ is provided to control the switching power supply 200 to enter the working mode. In this embodiment, the pulse width of the modulation signal DIM is consistent, so that the duty cycle of the drive signal Vg matches that of the modulation signal DIM.

[0146] Since the modulation signal DIM is a square wave signal with periodic voltage changes, the comparison signal CS periodically switches between high and low levels. When the modulation signal DIM is low, the comparison signal CS is in an invalid low-level state, and the counting unit 242 starts counting continuously. When the modulation signal DIM continuously outputs a square wave signal, the counting time of the counting unit 242 does not exceed half a cycle of the modulation signal DIM. At time t1, the modulation signal DIM stops outputting the square wave signal and continues to output a low level. The voltage value of the modulation signal DIM is less than the reference voltage Vref, and the comparison signal CS remains in an invalid low-level state. The counting unit 242 starts counting continuously. At time t2, the count value of the counting unit 242 reaches the counting threshold (in this embodiment, the counting threshold is one cycle of the modulation signal DIM), the standby control signal DJ flips to a low level, confirming standby control, providing a valid standby control signal DJ, controlling the switching power supply 200 to enter standby mode, stopping the supply of the first current I1, and the drive module 230 enters a low-power state.

[0147] The counting threshold (preset invalid level time) of the counting unit 242 is set according to the actual situation, and this application does not impose any special limitation on it. Specifically, based on the characteristics of the modulation signal DIM, the counting threshold of the counting unit 242 is greater than or equal to 2.

[0148] Figure 4A and Figure 4B A schematic diagram of the standby module of a switching power supply according to another embodiment of the present invention and a timing diagram of some of its signals are shown.

[0149] Reference Figure 4A and Figure 4B In this embodiment, the modulation signal DIM is an analog signal (e.g., an analog dimming signal), and the standby module 240 only includes a comparator 241.

[0150] The non-inverting input of comparator 241 receives the modulation signal DIM, and the inverting input receives the reference voltage Vref. Outside of the time interval t0 to t1, the voltage of the modulation signal DIM is less than the reference voltage Vref, the standby control signal DJ is low, the first current I1 is stopped, and the drive module 230 is in a low-power state. During the time interval t0 to t1, the voltage of the modulation signal DIM is greater than the reference voltage Vref, the standby control signal DJ is high, the first current I1 is output, and the pulse width of the drive signal Vg changes with the voltage of the modulation signal DIM.

[0151] The modulation signal DIM is an analog signal. At time t1, if the voltage of the modulation signal DIM is less than the reference voltage Vref, it can be directly confirmed as standby control without the need for reconfirmation based on counting, which can improve the standby control response speed.

[0152] Figure 5 A schematic diagram of the bias module of the switching power supply according to a first embodiment of the present invention is shown.

[0153] Reference Figure 5 In one embodiment of the present invention, the bias module 220 includes a bias unit 221, an input unit 222, an output unit 223, and a switching unit 224.

[0154] The input unit 221 generates a bias current based on the supply current; the bias unit 222 generates a first current I1 and a second current I2 based on the bias current; the output unit 223 outputs the first current and the second current to the drive module 230 and the standby module 240, respectively; and the switching unit 224 controls the conduction and deactivation of the first path based on the standby control signal. In this embodiment, the first path is the path between the input unit 222 and the bias unit 221.

[0155] Specifically, the bias module includes a bias unit 221, a first transistor to a sixth transistor (M1 to M6), and a first switch S1. In this embodiment, the first transistor M1, the second transistor M2, and the third transistor M3 are NMOS (N-Metal-Oxide-Semiconductor) transistors, and the fourth transistor M4, the fifth transistor M5, and the sixth transistor M6 are PMOS (P-Metal-Oxide-Semiconductor) transistors. The first switch S1 is, for example, a first switching transistor.

[0156] The input unit 222 includes a first current mirror unit and a second current mirror unit. The first current mirror unit, consisting of a first transistor M1 and a second transistor M2, mirrors the supply current provided by the power supply module 210 to the bias unit 221. The second current mirror unit, consisting of a first transistor M1 and a third transistor M3, mirrors the supply current output.

[0157] The switching unit 224 includes a first switch S1, which is connected between the second current mirror unit and the bias unit 221 and controls the on and off states according to the standby control signal.

[0158] The bias unit 221 provides a first current and a second current according to the bias current. In this embodiment, the first current and the second current are the currents flowing through the transistor M4.

[0159] The output unit 223 includes a third current mirror unit and a fourth current mirror unit, wherein the third current mirror unit outputs the first current mirror to the drive module; and the fourth current mirror unit outputs the second current mirror to the standby module.

[0160] The fourth transistor M4 and the sixth transistor M6 constitute the third current mirror unit, which mirrors the first current I1 and outputs it to the drive module 230.

[0161] The fourth transistor M4 and the fifth transistor M5 constitute the fourth current mirror unit, which mirrors the second current I2 and outputs it to the standby module 240.

[0162] When the switching power supply 200 is in normal working mode, the standby control signal DJ is in an invalid state, the first switch S1 is in a conducting state, the outputs of the first current mirror unit and the second current mirror unit are both provided to the bias unit 221, the bias current is high power, the first current and the second current are high output power, and the standby module 240 and the drive module 230 are in a high power consumption state.

[0163] When the switching power supply 200 is in standby mode, the standby control signal DJ is active, controlling the first switch S1 to be off. Only the output of the first current mirror unit is provided to the bias unit 221, the bias current is low power, the corresponding first current and second current are low output power, and the corresponding standby module 240 and drive module 230 are in a low power consumption state.

[0164] Figure 6 A schematic diagram of the bias module of a switching power supply according to a second embodiment of the present invention is shown. (Refer to...) Figure 6 In the bias module 220 of the second embodiment of the present invention, the bias module 220 includes a bias unit 221, an input unit 222, an output unit 223 and a switching unit 224.

[0165] The input unit 221 generates a bias current based on the supply current; the bias unit 222 generates a first current I1 and a second current I2 based on the bias current; the output unit 223 outputs the first current and the second current to the drive module 230 and the standby module 240, respectively; and the switching unit 224 controls the conduction and deactivation of the second path based on a standby control signal. In this embodiment, the second path is the path between the output unit 223 and the drive module 230 and / or the path between the output unit 223 and the standby module 240.

[0166] Specifically, the bias module 220 includes a bias unit 221, seventh to thirteenth transistors (M7 to M13), and a second switch S2 and a third switch S3. In this embodiment, the first transistor M7 and the eighth transistor M8 are NMOS transistors, and the ninth transistor M9, the tenth transistor M10, the eleventh transistor M11, the twelfth transistor M12, and the thirteenth transistor M13 are PMOS transistors. The second switch S2 is, for example, a second switching transistor, and the third switch S3 is, for example, a third switching transistor.

[0167] The input unit 221 includes a fifth current mirror unit, which mirrors the power supply current and outputs it to the bias unit.

[0168] The seventh transistor M7 and the eighth transistor M8 constitute the fifth current mirror unit, which mirrors the supply current to the bias unit 221.

[0169] The bias unit 221 provides a first current and a second current based on the input bias current. In this embodiment, the bias current of the bias unit 221 is the mirror output of the fifth current mirror unit on the power supply current, and the first current and the second current are both currents flowing through the ninth transistor M9.

[0170] The output unit includes a sixth current mirror unit, a seventh current mirror unit, an eighth current mirror unit, and a ninth current mirror unit. The sixth current mirror unit outputs the first current mirror image to the drive module; the seventh current mirror unit outputs the first current mirror image; the eighth current mirror unit outputs the second current mirror image to the standby module; and the ninth current mirror unit outputs the second current mirror image.

[0171] The ninth transistor M9 and the twelfth transistor M12 constitute the sixth current mirror unit, which mirrors the first current I1 and outputs it to the drive module 230.

[0172] The ninth transistor M9 and the thirteenth transistor M13 form the seventh current mirror unit, which mirrors the first current I1. The ninth transistor M9 and the eleventh transistor M11 form the eighth current mirror unit, which mirrors the second current I2.

[0173] The ninth transistor M9 and the tenth transistor M10 constitute the ninth current mirror unit, which mirrors the second current I2 and outputs it to the standby module 240.

[0174] The switching unit 224 includes a third switch S3 and a second switch S2, wherein the third switch S3 is connected between the ninth current mirror unit and the drive module 230. The second switch S2 is connected between the ninth current mirror unit and the standby module 240.

[0175] The second switch S2 and the third switch S3 are controlled to be turned on and off according to the standby control signal DJ.

[0176] In normal operating mode, the standby control signal DJ is at an invalid level, and both the second switch S2 and the third switch S3 are turned on.

[0177] In standby mode, the standby control signal DJ is at an active level, and both the second switch S2 and the third switch S3 are turned off.

[0178] Figure 7 A schematic diagram of the bias module of a switching power supply according to a third embodiment of the present invention is shown. Compared with the second embodiment, the second switch S2 in this embodiment is normally closed, and the second current I2 supplied to the standby module 240 remains unchanged.

[0179] In this embodiment, the bias unit 221 adjusts the magnitude of the first current I1 mirrored to the drive module 230 only according to the standby control signal DJ.

[0180] The rest of this embodiment is the same as the second embodiment, and will not be described again here.

[0181] The control circuit of the switching power supply provided by the present invention reuses the modulation signal as the standby enable signal of the standby module and provides the standby control signal according to the modulation signal. There is no need for a separate standby enable signal, which can reduce the setting of peripheral circuits that match the standby enable signal, reduce the implementation complexity of the switching power supply, and reduce costs.

[0182] Furthermore, a first current is provided to the drive module through a bias module, and the magnitude of the first current is adjusted according to the standby module to regulate the power consumption of the drive module.

[0183] Furthermore, a second current is provided to the standby module through a bias module, and the magnitude of the second current is adjusted according to the standby module to regulate the power consumption of the standby module.

[0184] Furthermore, the standby module includes a comparator and a counting unit. The comparator provides a comparison signal based on the comparison of the modulation signal and the reference voltage signal, and the counting unit provides a standby control signal based on the comparison signal and a preset invalid level duration.

[0185] Furthermore, when the effective level duration of the comparison signal is greater than a preset effective level duration, the standby control signal is at an effective level; when the effective level of the comparison signal is less than the preset effective level duration and the comparison signal is at an invalid level, the standby control signal is at an invalid level. This reduces interference from modulation signal fluctuations, provides a reliable standby control signal, avoids false triggering of standby control caused by modulation signal fluctuations, and improves system reliability.

[0186] The control circuit of the switching power supply of the present invention includes a standby module for generating a standby control signal based on a modulation signal and a reference signal; and a drive module for generating a drive signal based on the modulation signal and / or the standby control signal, wherein the drive signal is used to control the on and off states of a power switching transistor; wherein, when the standby control signal is at an active level, the drive signal keeps the power switching transistor in an off or on state. It reuses the modulation signal as a standby enable signal for standby control, eliminating the need for a separate standby enable signal, reducing the need for external circuitry matching the standby enable signal, lowering the complexity of the switching power supply implementation, and reducing costs.

[0187] As described above, these embodiments of the present invention do not exhaustively cover all details, nor do they limit the invention to the specific embodiments described. Clearly, many modifications and variations can be made based on the above description. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to effectively utilize the invention and its modifications. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A control circuit for a switching power supply, characterized in that, include: The power supply module generates power supply current based on the DC bus voltage; A bias module is used to generate a first current and a second current according to the power supply current and the standby control signal, and the bias module also adjusts the magnitude of the second current according to the standby control signal; The standby module is used to generate standby control signals based on the modulation signal and the reference signal; A drive module is used to generate a drive signal based on a modulation signal and a standby control signal, wherein the drive signal is used to control the on and off of the power switching transistor; Wherein, the first current supplies power to the drive module, and the second current supplies power to the standby module; When the standby control signal is at an active level, the drive signal keeps the power switch in the off state.

2. The control circuit according to claim 1, characterized in that, The modulation signal is an analog dimming signal or a pulse width dimming signal.

3. The control circuit according to claim 2, characterized in that, When the modulation signal is an analog dimming signal, the standby module includes: The comparator compares the voltage value of the modulated signal with the voltage value of the reference signal and outputs a standby control signal.

4. The control circuit according to claim 3, characterized in that, When the voltage value of the modulation signal is less than the voltage value of the reference signal, the standby control signal is at an active level; When the voltage value of the modulation signal is greater than the voltage value of the reference signal, the standby control signal is at an invalid level.

5. The control circuit according to claim 2, characterized in that, The standby module includes: The comparator compares the voltage value of the modulated signal with the voltage value of the reference signal and outputs a comparison signal. The counting unit generates a standby control signal based on the level state of the comparison signal and the preset invalid level duration.

6. The control circuit according to claim 5, characterized in that, When the modulated signal is less than the reference signal, the comparison signal is at an active level; when the modulated signal is greater than the reference signal, the comparison signal is at an inactive level.

7. The control circuit according to claim 6, characterized in that, When the effective level duration of the comparison signal is greater than the preset effective level duration, the standby control signal is at an effective level. When the effective level of the comparison signal is less than the preset effective level duration and the comparison signal is invalid, the standby control signal is invalid.

8. The control circuit according to claim 1, characterized in that, The bias module also adjusts the magnitude of the first current according to the standby control signal.

9. The control circuit according to claim 1, characterized in that, The bias module includes: The input unit is used to generate a bias current based on the supply current. A biasing unit is used to generate a first current and a second current based on the bias current; The output unit is used to output the first current and the second current to the drive module and the standby module, respectively; A switching unit is used to control the conduction and / or cutoff of the first path and / or the second path according to a standby control signal; The first path is the path between the input unit and the bias unit; the second path is the path between the output unit and the driver module and / or the path between the output unit and the standby module.

10. The control circuit according to claim 9, characterized in that, The input unit includes: The first current mirror unit mirrors and outputs the power supply current to the bias unit. The second current mirror unit mirrors the output of the power supply current. The switching unit includes a first switch connected between the second current mirror unit and the bias unit. The first switch is turned on and off according to the standby control signal.

11. The control circuit according to claim 9, characterized in that, The output unit includes: The third current mirror unit outputs the first current mirror image to the drive module; The fourth current mirror unit outputs the second current mirror to the standby module.

12. The control circuit according to claim 10, characterized in that, When the standby control signal is at an active level, the first switch is turned off; when the standby control signal is at an inactive level, the first switch is turned on.

13. The control circuit according to claim 9, characterized in that, The input unit includes: The fifth current mirror unit mirrors the power supply current and outputs it to the bias unit.

14. The control circuit according to claim 13, characterized in that, The output unit includes: The sixth current mirror unit outputs the first current mirror image to the drive module; The seventh current mirror unit mirrors and outputs the first current. The eighth current mirror unit outputs the second current image to the standby module; The ninth current mirror unit outputs the second current mirror.

15. The control circuit according to claim 14, characterized in that, in, The switching unit includes a third switch connected between the seventh current mirror unit and the driving module; wherein the third switch is turned on and off according to the standby control signal.

16. The control circuit according to claim 15, characterized in that, When the standby control signal is at an active level, the third switch is turned off; when the standby control signal is at an inactive level, the third switch is turned on.

17. The control circuit according to claim 14, characterized in that, in, The switching unit includes: The third switch is connected between the seventh current mirror unit and the drive module; A second switch is connected between the ninth current mirror unit and the standby module; The second switch and the third switch are turned on and off according to the standby control signal.

18. The control circuit according to claim 17, characterized in that, When the standby control signal is at an active level, the second switch and the third switch are turned off; when the standby control signal is at an inactive level, the second switch and the third switch are turned on.

19. A switching power supply, characterized in that, include: A rectifier bridge converts AC power into DC bus voltage. A power conversion circuit converts the DC bus voltage into a DC output voltage. Control circuit, including: The power supply module generates power supply current based on the DC bus voltage; The bias module is used to generate a first current and a second current based on the power supply current and the standby control signal; The standby module is used to generate standby control signals based on the modulation signal and the reference signal; A drive module is used to generate a drive signal based on a modulation signal and a standby control signal, wherein the drive signal is used to control the on and off of the power switching transistor; Wherein, the first current supplies power to the drive module, and the second current supplies power to the standby module; When the standby control signal is at an active level, the drive signal keeps the power switch in the off state.

20. The switching power supply according to claim 19, characterized in that, The modulation signal is an analog dimming signal or a pulse width dimming signal.

21. The switching power supply according to claim 20, characterized in that, When the modulation signal is an analog dimming signal, the standby module includes: The comparator compares the voltage value of the modulated signal with the voltage value of the reference signal and outputs a standby control signal.

22. The switching power supply according to claim 21, characterized in that, When the voltage value of the modulation signal is less than the voltage value of the reference signal, the standby control signal is at an active level; When the voltage value of the modulation signal is greater than the voltage value of the reference signal, the standby control signal is at an invalid level.

23. The switching power supply according to claim 20, characterized in that, The standby module includes: The comparator compares the voltage value of the modulated signal with the voltage value of the reference signal and outputs a comparison signal. The counting unit generates a standby control signal based on the level state of the comparison signal and the preset invalid level duration.

24. The switching power supply according to claim 23, characterized in that, When the modulated signal is less than the reference signal, the comparison signal is at an active level; when the modulated signal is greater than the reference signal, the comparison signal is at an inactive level.

25. The switching power supply according to claim 24, characterized in that, When the effective level duration of the comparison signal is greater than the preset effective level duration, the standby control signal is at an effective level. When the effective level of the comparison signal is less than the preset effective level duration and the comparison signal is invalid, the standby control signal is invalid.

26. The switching power supply according to claim 19, characterized in that, The bias module also adjusts the magnitude of the first current according to the standby control signal.

27. The switching power supply according to claim 19, characterized in that, The bias module includes: The input unit is used to generate a bias current based on the supply current. A biasing unit is used to generate a first current and a second current based on the bias current; The output unit is used to output the first current and the second current to the drive module and the standby module, respectively; A switching unit is used to control the conduction and cutoff of the first path or the second path according to the standby control signal; The first path is the path between the input unit and the bias unit; the second path is the path between the output unit and the driver module and / or the path between the output unit and the standby module.

28. The switching power supply according to claim 27, characterized in that, The input unit includes: The first current mirror unit mirrors and outputs the power supply current to the bias unit. The second current mirror unit mirrors the output of the power supply current. The switching unit includes a first switch connected between the second current mirror unit and the bias unit. The first switch is turned on and off according to the standby control signal.

29. The switching power supply according to claim 27, characterized in that, The output unit includes: The third current mirror unit outputs the first current mirror image to the drive module; The fourth current mirror unit outputs the second current mirror to the standby module.

30. The switching power supply according to claim 28, characterized in that, When the standby control signal is at an active level, the first switch is turned off; when the standby control signal is at an inactive level, the first switch is turned on.

31. The switching power supply according to claim 27, characterized in that, The input unit includes: The fifth current mirror unit mirrors the power supply current and outputs it to the bias unit.

32. The switching power supply according to claim 31, characterized in that, The output unit includes: The sixth current mirror unit outputs the first current mirror image to the drive module; The seventh current mirror unit mirrors and outputs the first current. The eighth current mirror unit outputs the second current image to the standby module; The ninth current mirror unit outputs the second current mirror.

33. The switching power supply according to claim 32, characterized in that, in, The switching unit includes a third switch connected between the seventh current mirror unit and the driving module; wherein the third switch is turned on and off according to the standby control signal.

34. The switching power supply according to claim 33, characterized in that, When the standby control signal is at an active level, the third switch is turned off; when the standby control signal is at an inactive level, the third switch is turned on.

35. The switching power supply according to claim 32, characterized in that, in, The switching unit includes: The third switch is connected between the seventh current mirror unit and the drive module; A second switch is connected between the ninth current mirror unit and the standby module; The second switch and the third switch are turned on and off according to the standby control signal.

36. The switching power supply according to claim 35, characterized in that, When the standby control signal is at an active level, the second switch and the third switch are turned off; when the standby control signal is at an inactive level, the second switch and the third switch are turned on.

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