Control circuit and control method for isolated switching converter

Abstract

The invention provides a control circuit and a control method for an isolated switching converter, a secondary controller receives and responds to a sleep control signal to generate a sleep request signal, when the sleep control signal is in a first state, the secondary controller enters a sleep mode and switches the sleep request signal to a third state, and when the sleep control signal is in a second state, the secondary controller enters a sleep mode; and the primary side controller enters the sleep mode in response to the sleep request signal in the third state, so that the primary side controller can enter the sleep mode along with the secondary side controller, and when the primary side controller and the secondary side controller enter the sleep mode, most internal functional modules and a signal isolator between the functional modules can be closed, so that the standby power consumption of the system can be effectively reduced. Meanwhile, based on the corresponding relation between the sleep control signal and the sleep request signal, the primary side controller can enter the wake-up mode along with the secondary side controller, and rapid wake-up of the system is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and particularly to a control circuit and a control method for an isolated switching converter. Background Art

[0002] Isolated switching converters are widely used in various power supply systems. An isolated switching converter generally includes a primary circuit and a secondary circuit. By controlling the on and off of power switches in the primary circuit and the secondary circuit, a constant voltage or a constant current output of the secondary circuit is achieved.

[0003] Meanwhile, a separate isolator is usually provided in the control circuit of the isolated switching converter. The isolator is used for signal transmission between the primary and secondary sides and realizes the drive interlock of the power switch tube in the primary circuit and the synchronous rectifier tube in the secondary circuit, preventing the drive commonality between the primary circuit and the secondary circuit. The circuit is simple and can optimize the system efficiency. However, the standby power consumption of the provided isolator and the used transmission and receiving circuits is relatively high. Therefore, it is necessary to provide an improved technical solution to reduce the standby power consumption of the system. Summary of the Invention

[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a control technical solution for an isolated switching converter to solve the problem of relatively high standby power consumption of the existing isolated switching converter.

[0005] To achieve the above purpose and other related purposes, the technical solution provided by the present invention is as follows.

[0006] A control circuit for an isolated switching converter, the isolated switching converter includes a primary circuit, a secondary circuit, and a transformer, the transformer is coupled between the primary circuit and the secondary circuit, and the control circuit includes:

[0007] A secondary controller, electrically connected to the secondary circuit, receiving a sleep control signal and generating a sleep request signal according to the sleep control signal. When the sleep control signal is in a first state, the secondary controller enters a sleep mode. When the sleep control signal is in a second state, the secondary controller enters a wake-up mode;

[0008] A primary controller, electrically connected to the primary circuit, receiving the sleep request signal. When the sleep request signal is in a third state, the primary controller enters a sleep mode. When the sleep request signal is in a fourth state, the primary controller enters a wake-up mode.

[0009] Optionally, the secondary side controller at least includes a secondary side logic circuit, a secondary side drive circuit, a detection circuit, and a transmission circuit. The detection circuit is used to detect the secondary side winding voltage of the secondary side circuit and send it to the secondary side logic circuit. The secondary side logic circuit generates a secondary side control signal and the sleep request signal according to the secondary side winding voltage and the sleep control signal. The secondary side drive circuit generates a secondary side switch drive signal according to the secondary side control signal to control the secondary side switch in the secondary side circuit. The sleep request signal is output to the primary side controller through the transmission circuit.

[0010] Optionally, the secondary side controller at least includes a secondary side logic circuit, a detection circuit, and a transmission circuit. The detection circuit is used to detect the secondary side winding voltage of the secondary side circuit and send it to the secondary side logic circuit. The secondary side logic circuit generates the sleep request signal according to the secondary side winding voltage and the sleep control signal. The sleep request signal is output to the primary side controller through the transmission circuit.

[0011] Optionally, the control circuit further includes a signal isolator. The signal isolator receives the sleep request signal sent by the secondary side controller and isolates and transmits it to the primary side controller.

[0012] Optionally, the primary side controller includes a primary side receiving circuit, an undervoltage protection circuit, a primary side logic circuit, and a primary side drive circuit. The primary side receiving circuit receives the sleep request signal and sends it to the primary side logic circuit. The undervoltage protection circuit is electrically connected to the primary side circuit and is used to detect the supply voltage of the primary side controller to obtain an undervoltage protection signal. The primary side logic circuit generates a primary side control signal according to the sleep request signal and the undervoltage protection signal. The primary side drive circuit generates a primary side switch drive signal according to the primary side control signal to control the primary side switch in the primary side circuit.

[0013] Optionally, when the secondary side controller detects that the sleep control signal is in the first state, it turns off the detection circuit, controls the transmission circuit to work periodically, controls the secondary side switch to remain off through the secondary side switch drive signal, and switches the sleep request signal to the third state. The secondary side controller enters the sleep mode.

[0014] Optionally, when the secondary side controller detects that the sleep control signal is in the first state, it turns off the detection circuit, controls the transmission circuit to work periodically, and switches the sleep request signal to the third state. The secondary side controller enters the sleep mode.

[0015] Optionally, when the primary controller detects that the sleep request signal is in the third state, the undervoltage protection circuit and the primary drive circuit are turned off, and the primary receiving circuit is controlled to operate periodically, and the primary controller enters the sleep mode.

[0016] Optionally, when the primary controller and the secondary controller enter the sleep mode, the secondary controller detects the output voltage of the secondary circuit. When the output voltage of the secondary circuit is lower than the first threshold, the secondary controller enters the partial wake-up mode, and the secondary logic circuit switches the sleep request signal from the third state to the fifth state, and sends the sleep request signal to the primary controller through the sending circuit.

[0017] Optionally, when the primary controller detects that the sleep request signal is in the fifth state, the primary controller enters the partial wake-up mode, turns on the primary drive circuit, and controls the primary switch to act in response to the sleep request signal to supplement the output voltage of the secondary circuit.

[0018] Optionally, when the secondary controller enters the partial wake-up mode, the detection circuit is turned on. When it is detected that the secondary winding voltage of the secondary circuit changes corresponding to the sleep request signal, the secondary logic circuit switches the sleep request signal from the fifth state to the third state, and the secondary controller returns to the sleep mode.

[0019] Optionally, when the secondary controller detects that the sleep control signal is in the second state, the detection circuit and the sending circuit are turned on, and the sleep request signal is switched to the fourth state, and the secondary controller enters the wake-up mode.

[0020] Optionally, when the primary logic circuit detects that the sleep request signal is in the fourth state, the undervoltage protection circuit, the primary drive circuit and the primary receiving circuit are turned on, and the primary switch is controlled to act through the primary switch drive signal, and the primary controller enters the wake-up mode.

[0021] Optionally, the primary controller detects the state of the sleep request signal through one or more of the count value, frequency or encoded information included in the sleep request signal received within a preset time period.

[0022] A control method for an isolated switch converter, the isolated switch converter includes a primary circuit, a secondary circuit and a transformer, the transformer is coupled between the primary circuit and the secondary circuit, the primary circuit is controlled by a primary controller, and the secondary circuit is controlled by a secondary controller. The control method includes:

[0023] The secondary controller receives and responds to a sleep control signal. When the secondary controller detects that the sleep control signal is in the first state, it generates a sleep request signal in the third state according to the sleep control signal, and the secondary controller enters the sleep mode;

[0024] The primary controller receives and responds to the sleep request signal. When the primary controller detects that the sleep request signal is in the third state, the primary controller enters the sleep mode.

[0025] Optionally, the control method further includes:

[0026] When the primary controller and the secondary controller enter the sleep mode, the output voltage of the secondary circuit is detected;

[0027] When it is detected that the output voltage of the secondary circuit is lower than the first threshold, the secondary controller enters the partial wake-up mode and switches the sleep request signal from the third state to the fifth state;

[0028] When the primary controller detects that the sleep request signal is in the fifth state, the primary controller enters the partial wake-up mode and controls the primary switch to act in response to the sleep request signal to supplement the power supply voltage of the primary controller and the output voltage of the secondary circuit, so that the output voltage of the secondary circuit is not lower than the first threshold.

[0029] Optionally, the control method further includes:

[0030] When the secondary controller detects that the sleep control signal is in the second state, the secondary controller enters the wake-up mode and switches the sleep request signal to the fourth state;

[0031] When the primary controller detects that the sleep request signal is in the fourth state, the primary controller enters the wake-up mode and controls the primary switch to act.

[0032] Optionally, the secondary controller at least includes a secondary logic circuit, a secondary drive circuit, a detection circuit and a transmission circuit. The detection circuit is used to detect the secondary winding voltage of the secondary circuit and send it to the secondary logic circuit. The control method further includes:

[0033] The secondary logic circuit generates a secondary control signal and the sleep request signal according to the secondary winding voltage and the sleep control signal. The secondary drive circuit generates a secondary switch drive signal according to the secondary control signal to control the secondary switch in the secondary circuit. The sleep request signal is output to the primary controller through the transmission circuit.

[0034] Optionally, the secondary side controller at least includes a secondary side logic circuit, a detection circuit, and a transmission circuit. The detection circuit is configured to detect the secondary side winding voltage of the secondary side circuit and send it to the secondary side logic circuit. The control method further includes:

[0035] The secondary side logic circuit generates the sleep request signal according to the secondary side winding voltage and the sleep control signal, and the sleep request signal is output to the primary side controller through the transmission circuit.

[0036] Optionally, the primary side controller includes a primary side receiving circuit, an undervoltage protection circuit, a primary side logic circuit, and a primary side driving circuit. The undervoltage protection circuit is electrically connected to the primary side circuit and is configured to detect the supply voltage of the primary side controller to obtain an undervoltage protection signal. The control method further includes:

[0037] The primary side receiving circuit receives the sleep request signal and sends it to the primary side logic circuit. The primary side logic circuit generates a primary side control signal according to the sleep request signal and the undervoltage protection signal, and the primary side driving circuit generates a primary side switch driving signal according to the primary side control signal to control the primary side switch in the primary side circuit.

[0038] Optionally, the control method further includes:

[0039] When the secondary side controller detects that the sleep control signal is in the first state, it turns off the detection circuit, controls the transmission circuit to work periodically, controls the secondary side switch to remain off through the secondary side switch driving signal, and switches the sleep request signal to the third state. The secondary side controller enters the sleep mode.

[0040] Optionally, the control method further includes:

[0041] When the secondary side controller detects that the sleep control signal is in the first state, it turns off the detection circuit, controls the transmission circuit to work periodically, and switches the sleep request signal to the third state. The secondary side controller enters the sleep mode.

[0042] Optionally, the control method further includes:

[0043] When the primary side controller detects that the sleep request signal is in the third state, it turns off the undervoltage protection circuit and the primary side driving circuit, and controls the primary side receiving circuit to work periodically. The primary side controller enters the sleep mode.

[0044] Optionally, the primary side controller detects the state of the sleep request signal through one or more of the count value, frequency, or encoded information included in the sleep request signal received within a preset time period.

[0045] As described above, the control circuit and control method for an isolated switch converter provided by the present invention at least have the following

[0046] Beneficial effects:

[0047] The secondary controller receives and responds to the sleep control signal, and generates a sleep request signal according to the sleep control signal. When the sleep control signal is in the first state, the secondary controller enters the sleep mode and switches the sleep request signal to the third state. The primary controller enters the sleep mode in response to the sleep request signal in the third state, so that the primary controller can follow the secondary controller into the sleep mode. When both enter the sleep mode, some high-power-consuming functional modules inside are turned off, and the signal isolator and its receiving and transmitting circuits between the primary and secondary circuits work periodically, which can effectively reduce the standby power consumption of the system. At the same time, based on the correspondence between the sleep control signal and the sleep request signal, the primary controller can also follow the secondary controller to exit the sleep mode and enter the partial wake-up mode or the wake-up mode, ensuring the power supply condition of the control circuit and the fast wake-up of the system. Description of the Drawings

[0048] Figure 1 It is a schematic circuit diagram of an isolated switch converter coupled with a control circuit in an embodiment of the present invention.

[0049] Figure 2 It is a schematic waveform diagram of key signals of an isolated switch converter coupled with a control circuit in an embodiment of the present invention.

[0050] Figure 3 It is a schematic waveform diagram of key signals of an isolated switch converter coupled with a control circuit entering the partial wake-up mode in the sleep mode in an embodiment of the present invention.

[0051] Figure 4 It is a schematic step diagram of a control method for an isolated switch converter in the present invention.

[0052] Figure 5 It is a schematic circuit diagram of an isolated switch converter coupled with a control circuit in another embodiment of the present invention. Detailed Embodiments

[0053] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0054] Please refer toFigures 1 to 5 It should be noted that the illustrations provided in this embodiment only schematically illustrate the basic concept of the present invention. Therefore, only the components related to the present invention are shown in the drawings, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and proportion of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex. At the same time, the "time" and "when..." referred to in this specification are both time points, that is, the moment when a certain event occurs; "high level" means that a level that can be detected and judged as valid indicates that a certain component or module performs corresponding actions; "low level" means that a level that can be detected and judged as invalid or a level that cannot be detected indicates that a certain component or module performs corresponding actions; "signal" can represent some specific electrical signals / magnetic signals, which can be represented by a specific waveform, or can represent some information transmitted in a circuit, which can be represented by a specific value. The above terms are only for the convenience of clear description and are not used to limit the scope of implementation of the present invention. The change or adjustment of their relative semantics, without substantial change in technical content, should also be regarded as the scope of implementation of the present invention.

[0055] Figure 1 The following is a schematic circuit diagram of an isolated switch converter coupled with a control circuit in an embodiment of the present invention. It should be noted that Figure 1 in this embodiment of the present invention, the flyback converter is taken as an example to illustrate the technical solutions of the control circuit and the control method. However, the applicable objects of the control circuit and the control method are not limited to the flyback converter as Figure 1 shown, and can also be other types of isolated switch converters, such as push-pull converters, half-bridge converters, full-bridge converters, and forward converters, etc., which are not limited here.

[0056] Specifically, as Figure 1 shown, the isolated switch converter includes a primary circuit, a secondary circuit, and a transformer T1 coupled between the primary circuit and the secondary circuit and providing electrical isolation. Among them, the primary circuit and the secondary circuit are electrically isolated and are respectively connected to different ground terminals. The transformer T1 includes a primary winding W1 and a secondary winding W2. The primary circuit is coupled to the primary winding W1 of the transformer T1, and the secondary circuit is coupled to the secondary winding W2 of the transformer T1.

[0057] More specifically, as Figure 1As shown, the primary-side circuit includes an input capacitor Cbus and a primary-side switch G1. The first terminal of the input capacitor Cbus is coupled to the primary winding W1 of the transformer T1. The second terminal of the input capacitor Cbus is connected to the ground terminal of the primary-side circuit. The drain of the primary-side switch G1 is connected to the primary winding W1 of the transformer T1. The source of the primary-side switch G1 is connected to the ground terminal of the primary-side circuit. The gate of the primary-side switch G1 is connected to the primary controller to receive the primary-side switch drive signal GATE.

[0058] Specifically, as Figure 1 shown, the primary-side circuit further includes an auxiliary winding W3, a diode, and a supply capacitor Cvcc. The auxiliary winding W3 is coupled to the transformer T1. One end of both the auxiliary winding W3 and the supply capacitor Cvcc is connected to the ground terminal of the primary-side circuit. The other end of the supply capacitor Cvcc is coupled to the other end of the auxiliary winding W3 through the diode. Specifically, the cathode of the diode is connected to the supply capacitor Cvcc, and the anode of the diode is connected to the auxiliary winding W3. In practical applications, the supply capacitor Cvcc can be charged through the auxiliary winding W3 to ensure that a sufficient supply voltage VCC is provided to the primary controller. At the same time, since the auxiliary winding W3 is coupled to the transformer T1, the output voltage of the auxiliary winding W3 (i.e., the supply voltage VCC provided by the supply capacitor Cvcc) is proportional to the output voltage VOUT of the secondary-side circuit. Therefore, maintaining the supply voltage VCC within a sufficient range can ensure the normal operation of the primary controller and can also ensure that the output voltage VOUT will not be too low, enabling the isolated switch converter to quickly establish the output and enter the normal operating state when awakened.

[0059] More specifically, as Figure 1 shown, the secondary-side circuit includes a secondary-side switch SR, an output capacitor Cout, and a sampling circuit. The first terminal of the output capacitor Cout is coupled to the secondary winding W2 of the transformer T1. The second terminal of the output capacitor Cout is connected to the ground terminal of the secondary-side circuit. The drain of the secondary-side switch SR is connected to the secondary winding W2 of the transformer T1. The source of the secondary-side switch SR is connected to the ground terminal of the secondary-side circuit. The gate of the secondary-side switch SR is connected to the secondary controller for receiving the secondary-side switch drive signal. The sampling circuit is connected to the output terminal of the isolated switch converter and is used to sample the output voltage VOUT of the converter to form a feedback voltage FB. The feedback voltage FB can directly or indirectly reflect the condition of the output voltage. Further, the sampling circuit can also be electrically connected to the secondary controller to send the feedback voltage FB to the secondary controller, and the secondary controller can modulate the control signal of the secondary-side switch SR according to the feedback voltage FB. Exemplarily, the sampling circuit can be a Figure 1 resistive voltage-divider circuit as shown, or other alternative technical means for detecting voltage / current.

[0060] Specifically, as Figure 1As shown, the present invention provides a control circuit for an isolated switching converter, and the control circuit includes:

[0061] A secondary controller, electrically connected to the secondary circuit, receiving a sleep control signal Ctrl_s and generating a sleep request signal Req_s according to the sleep control signal Ctrl_s. When the sleep control signal Ctrl_s is in the first state, the secondary controller enters the sleep mode. When the sleep control signal Ctrl_s is in the second state, the secondary controller enters the wake-up mode. The sleep request signal Req_s is converted into a sleep request signal Req_p through a signal isolator and received by the primary controller. It should be noted that the signal Req_s and the signal Req_p contain the same information, and the difference is that they have different reference grounds due to the function of the isolator. For the sake of simplicity, they are expressed as the same signal in the embodiments of the present invention.

[0062] A primary controller, electrically connected to the primary circuit, receiving the sleep request signal Req_s. When the sleep request signal Req_s is in the third state, the primary controller enters the sleep mode. When the sleep request signal Req_s is in the fourth state, the primary controller enters the wake-up mode.

[0063] More specifically, as Figure 1 shown, the secondary controller at least includes a secondary logic circuit, a secondary drive circuit, a detection circuit, and a transmission circuit. The secondary logic circuit receives the sleep control signal Ctrl_s and generates a sleep request signal Req_p according to the sleep control signal Ctrl_s. The sleep request signal Req_p is output to the primary controller through the transmission circuit. The detection circuit is used to detect the secondary winding voltage Forward of the secondary circuit and send it to the secondary logic circuit. The secondary logic circuit receives the sleep control signal Ctrl_s and the secondary winding voltage Forward, generates a secondary control signal, and sends it to the secondary drive circuit. The secondary drive circuit generates a secondary switch drive signal according to the secondary control signal to drive the secondary switch SR in the secondary circuit.

[0064] Among them, the secondary drive circuit is connected to the gate (or control terminal) of the secondary switch SR. The secondary drive circuit sends a secondary switch control signal to the gate of the secondary switch SR to control the switching action of the secondary switch SR. The detection circuit is connected to the secondary winding W2 to detect the secondary winding voltage Forward of the secondary circuit.

[0065] Specifically, as Figure 1 shown, the secondary controller may further include a loop control circuit, receiving the feedback voltage FB output by the secondary circuit, and generating a corresponding control signal to send to the secondary logic circuit. The secondary logic circuit adjusts the secondary control signal accordingly, and further controls the secondary switch SR, thereby adjusting the output voltage VOUT and the feedback voltage FB of the secondary circuit.

[0066] Specifically, as Figure 1 shown, the control circuit includes:

[0067] A primary controller, electrically connected to the primary circuit, receives a sleep request signal Req_p. When the sleep request signal Req_p is in the third state, the primary controller enters the sleep mode. When the sleep request signal Req_p is in the fourth state, the primary controller enters the wake-up mode.

[0068] The primary controller at least includes a primary receiving circuit, an undervoltage protection circuit, a primary logic circuit, and a primary driving circuit. The primary receiving circuit receives the sleep request signal Req_p and sends it to the primary logic circuit. The undervoltage protection circuit is electrically connected to the primary circuit and is used to detect the supply voltage VCC of the primary controller to obtain an undervoltage protection signal. The primary logic circuit generates a primary control signal according to the sleep request signal Req_p and the undervoltage protection signal. The primary driving circuit generates a primary switch driving signal GATE according to the primary control signal to control the primary switch G1 in the primary circuit.

[0069] Among them, the primary driving circuit is connected to the gate (or control terminal) of the primary switch G1. The primary driving circuit sends a primary switch control signal (i.e., a pulse width modulation control signal PWM) to the gate of the primary switch G1 to control the switching action of the primary switch G1. The undervoltage protection circuit is connected to one end of the auxiliary winding W3 of the power supply capacitor Cvcc to detect the supply voltage VCC on the power supply capacitor Cvcc.

[0070] Specifically, as Figure 1 shown, the control circuit further includes:

[0071] A signal isolator, receives the sleep request signal Req_s sent by the secondary controller, converts it into the sleep request signal Req_p and transmits it to the primary controller, and the signals Req_s and Req_p are isolated from each other.

[0072] In practical applications, a magnetic coupling isolator, a capacitive coupling isolator, or a digital isolator, etc., can be selected as the signal isolator between the primary controller and the secondary controller. This signal isolator consumes very little power in the sleep mode, so that the standby power consumption of the entire system in the sleep mode can be further reduced.

[0073] In addition, the secondary winding voltage Forward sensed by the detection circuit reflects the operating state of the primary circuit. In the present invention, the secondary controller can also correspondingly adjust the secondary switch drive signal generated by the secondary drive circuit and the operating state of the secondary controller according to the change of the secondary winding voltage Forward sensed by the detection circuit. For example, the response status of the primary controller to the sleep request signal Req_p can be judged according to the change of the secondary winding voltage Forward, and then the operating mode of the primary circuit can be judged.

[0074] Among them, the primary controller can enter the sleep mode, semi-wake-up mode, and wake-up mode following the secondary controller, which are outlined as follows;

[0075] As Figure 1 shown, when the secondary controller detects that the sleep control signal Ctrl_s is in the first state, it turns off the detection circuit, controls the transmission circuit to work periodically, controls the secondary switch SR to remain off through the secondary switch drive signal, and switches the sleep request signal Req_s to the third state, and the secondary controller enters the sleep mode; when the primary controller detects that the sleep request signal Req_p is in the third state, it turns off the under-voltage protection circuit and the primary drive circuit, and controls the primary receiving circuit to work periodically, so that the primary controller enters the sleep mode.

[0076] When the primary controller and the secondary controller enter the sleep mode, the secondary controller detects the output voltage VOUT of the secondary circuit. When the output voltage VOUT of the secondary circuit is lower than the first threshold (the first threshold is less than the output voltage when the switching converter operates normally), the secondary controller enters the partial wake-up mode, and the secondary logic circuit switches the sleep request signal Req_s from the third state to the fifth state, and sends the sleep request signal Req_p to the primary controller through the transmission circuit; when the primary controller detects that the sleep request signal Req_p is in the fifth state, the primary controller enters the partial wake-up mode, turns on the primary drive circuit, and controls the primary switch G1 to act in response to the sleep request signal Req_p to supplement the output voltage VOUT of the secondary circuit and the supply voltage VCC of the primary controller.

[0077] When the secondary controller enters the partial wake-up mode, the detection circuit is turned on. When it detects that the secondary winding voltage Forward of the secondary circuit changes corresponding to the sleep request signal Req_p, that is, the detection result of the secondary winding voltage Forward is consistent with the operation of the primary switch controlled by the sleep request signal Req_p, it indicates that the operation of the primary switch G1 has supplemented the output voltage VOUT of the secondary circuit and the supply voltage of the primary side. The secondary logic circuit switches the sleep request signal Req_p from the fifth state to the third state, and the secondary controller returns to the sleep mode.

[0078] When the secondary - side controller detects that the sleep control signal Ctrl_s is in the second state, it turns on the detection circuit and the transmission circuit, and switches the sleep request signal Req_p to the fourth state. The secondary - side controller enters the wake - up mode. When the primary - side logic circuit detects that the sleep request signal Req_p is in the fourth state, it turns on the under - voltage protection circuit, the primary - side drive circuit, and the primary - side receiving circuit, and controls the operation of the primary - side switch G1 through the primary - side switch drive signal GATE, so that the primary - side controller enters the wake - up mode.

[0079] It should be noted that the secondary - side logic circuit detects the state of the sleep control signal Ctrl_s through at least one of the level high - low state or the coding information of the sleep control signal Ctrl_s, and identifies whether the specific state of the sleep control signal Ctrl_s is the first state or the second state. The primary - side logic circuit detects the state of the sleep request signal Req_p through one or more of the count value, frequency, or coding information contained in the sleep request signal Req_p received within a preset time period, and identifies which one of the third state, the fourth state, and the fifth state is the specific state of the sleep request signal Req_p. Further, the turning on and off of each functional module in the primary - side controller and the secondary - side controller can be synchronously controlled by an enable signal in response to the sleep control signal Ctrl_s and the sleep request signal Req_p, or can be controlled by the primary - side logic circuit and the secondary - side logic circuit in response to the sleep control signal Ctrl_s and the sleep request signal Req_p.

[0080] The following combines Figures 2 - 3 the waveform timing diagram shown in Figure 1 to elaborate in detail on the specific control principle of the control circuit for the isolated switch - mode converter shown.

[0081] At time t1, the sleep control signal Ctrl_s sent by the protocol chip to the secondary - side controller changes from low level (representing the second state of the sleep control signal Ctrl_s) to high level (representing the first state of the sleep control signal Ctrl_s), indicating that the secondary - side controller enters the sleep mode, turns off the detection circuit, controls the transmission circuit to work periodically, controls the secondary - side switch SR to remain off through the secondary - side switch drive signal, and switches the sleep request signal Req_p to the third state. At this time, the secondary - side controller switches the output voltage VOUT of the secondary - side circuit from the normal - working voltage value to the first threshold. In another embodiment, the secondary - side controller generates as Figure 2The Sleep_sec signal shown synchronously controls the detection circuit to turn off, the transmission circuit to work periodically, and the secondary switch SR to remain off. It should be noted that the protocol chip in the present invention can be a protocol module co-packaged with the secondary controller or an element used in an independent package, and the protocol it uses is not limited in the present invention, as long as it can provide a sleep control signal Ctrl_s recognizable by the secondary controller. Further, the sleep control signal Ctrl_s can be derived from the detection of the load port by the protocol chip or from a microcontroller or other communication channels, and the present invention does not limit this.

[0082] At time t2, the secondary controller sends the first pulse of the sleep request signal Req_s in the sleep mode. At this time, the frequency of the sleep request signal Req_s sent by the secondary controller is relatively low, indicating that the sleep request signal Req_s is in the third state.

[0083] At time t3, if the primary controller detects that the frequency of the sleep request signal Req_p is relatively low and within a preset range for several consecutive cycles, the primary controller enters the sleep mode in response to the sleep request signal Req_p, turns off the undervoltage protection circuit and the primary drive circuit, and controls the primary receiving circuit to work periodically. For example, every 1 ms, it works for 64 μs, and sleeps for the rest of the time to reduce power consumption. The primary drive circuit does not work, and the primary switch G1 stops operating. After that, the power consumption of the primary controller decreases. In one embodiment, the primary controller generates a Sleep_pri signal as shown in Figure 2 to synchronously turn off the undervoltage protection circuit and the primary drive circuit and control the primary receiving circuit to work periodically. In another embodiment, the primary receiving circuit is controlled to work periodically through the primary receiving circuit enable signal RX_EN. As shown in Figure 2 the high level of the enable signal RX_EN indicates that the primary receiving circuit is working normally, and the short pulse of the enable signal RX_EN indicates periodic work. For example, every 1 ms, it works for 64 μs, and sleeps for the rest of the time.

[0084] During the time period from t3 to t6, both the secondary controller and the primary controller enter the sleep mode, and the power consumption of the control circuit in the sleep mode (standby mode) decreases.

[0085] Further, when the secondary controller enters the sleep mode, the secondary controller continuously detects the output voltage VOUT of the secondary circuit. If it detects that the output voltage VOUT of the secondary circuit is lower than the first threshold (for example, 4V), the secondary controller enters the partial wake-up mode. See Figure 3, at time t4, the secondary controller detects that VOUT drops to the first threshold and issues a pulse train composed of several short pulse signals with a fixed period as the sleep request signal Req_s (representing the fifth state of the sleep request signal Req_p, the period and quantity of which can be adjusted).

[0086] It should be noted that, in order to further save power, the secondary controller can periodically detect the output voltage VOUT of the secondary circuit in the sleep state. The primary receiving circuit is in a periodic working state at this time. If a short pulse of the sleep request signal Req_p is received during the normal working time period indicated by the high level of the signal RX_EN, for example, the primary controller will turn on the main switch tube in response to the short pulse, and a spike will appear in the corresponding primary current IL, as shown at time t4. At this time, after the secondary controller detects the response of the primary controller through the winding voltage Forward, it can choose to stop sending the sleep request signal Req_s in the fifth state and continue to send the sleep request signal Req_s in the third state in the sleep mode. After time t4, since the main switch tube conducts for a period of time, some energy is transferred from the input side of the switch converter to the output side, causing the VCC voltage to rise. It should be noted that, for better control effect, the sleep request signals Req_s in the third state and the fifth state issued by the secondary controller can adopt the same pulse train, and after the secondary controller detects the response pulse train of the primary controller through the winding voltage Forward, it chooses to stop sending the remaining pulses in the pulse train that have not been sent yet. During the time period when the secondary controller has entered the sleep state while the primary controller has not entered the sleep state (for example Figure 2 the time period from t2 to t3 shown), since the receiving circuit of the primary controller is in the normal working state, it will respond and turn on the main switch tube when receiving the first pulse of each pulse train, and after the secondary controller detects the response pulse train of the primary controller through the winding voltage Forward, it stops sending the remaining pulses in the pulse train that have not been sent yet, so that the output voltage can be maintained near the first threshold voltage (for example, 4V). Adopting the sleep request signal Req_s and the control method as described above, the key waveforms are also as Figure 2 shown.

[0087] Continue to refer to Figure 2 , at time t4, the sleep request signal Req_s in the fifth state sent by the secondary controller is received and responded to by the primary controller. It should be noted that the primary controller only needs partial wake-up in response to the sleep request signal Req_p in the fifth state, that is, only the primary drive circuit is turned on to control the operation (turning on and off) of the primary switch G1 to supplement the supply voltage VCC of the primary side and the output voltage VOUT of the secondary circuit.

[0088] At time t5, the secondary side controller and the primary side controller enter the partial wake-up mode from the sleep mode, replenishing the primary side power supply voltage VCC and the output voltage VOUT of the secondary side circuit, so that the output voltage VOUT of the secondary side circuit is roughly stable at 4V.

[0089] At time t6, the sleep control signal Ctrl_s sent by the protocol chip changes from a high level (indicating the first state of the sleep control signal Ctrl_s) to a low level (indicating the second state of the sleep control signal Ctrl_s), and the secondary side controller enters the wake-up mode, turns on the detection circuit and the sending circuit, and after waking up, the secondary side controller will adjust the output voltage VOUT of the secondary side circuit back to the output voltage during normal operation (e.g., 5V), and switch the sleep request signal Req_s to the fourth state, and send out a number of sleep request signal Req_s pulses (indicating the fourth state of the sleep request signal Req_p). At this time, the frequency of the sleep request signal Req_p pulses can be higher than the frequency of the sleep request signal Req_p pulses in the sleep mode.

[0090] At time t7, the primary-side receiving circuit is still in a periodic working state, and the primary-side controller receives and responds to a pulse of the sleep request signal Req_p of the secondary-side controller, and counts to 1.

[0091] At time t8, the primary receiving circuit is still in the periodic working state. The primary controller receives the sleep request signal Req_p for the second consecutive wake-up window and can choose to respond or not, but the count will be 2. Figure 2 In the embodiment shown, the primary side controller is unresponsive.

[0092] At time t9, the primary receiving circuit is still in the periodic working state. The primary controller receives the sleep request signal Req_p for the third consecutive wake-up window and can choose to respond or not, but the count will be 3. Figure 2 In the illustrated embodiment, the primary side controller responds to a pulse of the sleep request signal Req_p.

[0093] At time t10, the primary side receiving circuit is still in a periodic working state. The primary side controller receives the sleep request signal Req_p for the fourth consecutive wake-up window. The primary side controller exits the sleep mode and enters the wake-up mode. The undervoltage protection circuit, the primary side drive circuit and the primary side receiving circuit are all turned on. In response to the sleep request signal Req_p, the primary side switch G1 is controlled to operate through the primary side switch drive signal GATE to resume normal operation.

[0094] At time t11, the output voltage VOUT of the secondary circuit returns to 5V, and the sleep stage ends.

[0095] It should be noted that there can be various alternative criteria for the primary side controller to exit the sleep mode and enter the wake-up mode. For example, it can be judged according to the count value within a period of time, or the sleep request signal Req_p can be encoded, or the frequency of the sleep request signal Req_p can be detected and judged, etc. In addition, as Figure 2 shown, similar to the process of the aforementioned primary side controller and secondary side controller entering the sleep mode, when exiting the sleep mode, the primary side sleep control signal Sleep_pri can also be used to synchronously control the turn-on of the undervoltage protection circuit and the primary side drive circuit, and control the normal operation of the primary side receiving circuit (for example, at time t10, the primary side sleep control signal Sleep_pri switches from high level to low level), and use the secondary side sleep control signal Sleep_sec to synchronously control the turn-on of the detection circuit and the normal operation of the sending circuit (for example, at time t6, the secondary side sleep control signal Sleep_sec switches from high level to low level).

[0096] Based on the above design idea of the control circuit for the isolated switch converter, as Figure 4 shown, the present invention also provides a control method for an isolated switch converter. The isolated switch converter includes a primary side circuit, a secondary side circuit, and a transformer, and the transformer is coupled between the primary side circuit and the secondary side circuit. The primary side circuit is controlled by a primary side controller, and the secondary side circuit is controlled by a secondary side controller. The method includes the steps:

[0097] S1. The secondary side controller receives and responds to a sleep control signal. When the secondary side controller detects that the sleep control signal is in the first state, a sleep request signal in the third state is generated according to the sleep control signal, and the secondary side controller enters the sleep mode;

[0098] S2. The primary side controller receives and responds to the sleep request signal. When the primary side controller detects that the sleep request signal is in the third state, the primary side controller enters the sleep mode;

[0099] S3. When the primary side controller and the secondary side controller enter the sleep mode, the output voltage of the secondary side circuit is detected;

[0100] S4. When it is detected that the output voltage of the secondary side circuit is lower than the first threshold, the secondary side controller enters the partial wake-up mode and switches the sleep request signal from the third state to the fifth state;

[0101] S5. When the primary side controller detects that the sleep request signal is in the fifth state, the primary side controller enters the partial wake-up mode and controls the primary side switch to act in response to the sleep request signal to supplement the power supply voltage of the primary side controller and the output voltage of the secondary side circuit, so that the output voltage of the secondary side circuit is not lower than the first threshold;

[0102] S6. When the secondary controller detects that the sleep control signal is in the second state, the secondary controller enters the wake-up mode and switches the sleep request signal to the fourth state;

[0103] S7. When the primary controller detects that the sleep request signal is in the fourth state, the primary controller enters the wake-up mode and controls the primary switch to act.

[0104] Among them, the specific step process of the above control method can be analyzed with reference to the specific working principle of the above control circuit for the isolated switch converter, which will not be elaborated here.

[0105] Based on the design idea of the above control circuit for the isolated switch converter, as Figure 5 shown, the present invention also provides a control circuit for an isolated switch converter. Different from the Figure 1 embodiment in it, the secondary circuit of the isolated switch converter includes a freewheeling diode D1 and an output capacitor Cout, and does not need to use a synchronous rectifier tube SR (i.e., the secondary switch SR). The anode of the freewheeling diode D1 is coupled to the ground terminal of the secondary circuit, and the cathode is coupled to the Forward end of the secondary winding W2. Correspondingly, the secondary controller in the control circuit includes a detection circuit, a secondary logic circuit, a transmission circuit, and a loop control circuit, and does not include a secondary drive circuit. In the Figure 5 shown embodiment, after the secondary controller enters the sleep mode, it does not need to control the synchronous rectifier tube SR to turn off. The freewheeling diode D1 on the secondary side replaces the Figure 1 function of the synchronous rectifier tube SR in the embodiment. The specific working process of the control circuit can be analyzed with reference to the above Figures 2 - 4 and the corresponding specific working principle, which will not be elaborated here.

[0106] In summary, in the control circuit and control method for the isolated switch converter provided by the present invention, the secondary controller receives and responds to the sleep control signal to generate a sleep request signal. When the sleep control signal is in the first state, the secondary controller enters the sleep mode and switches the sleep request signal to the third state. The primary controller enters the sleep mode in response to the sleep request signal in the third state, so that the primary controller can follow the secondary controller to respond to the sleep demand and enter the sleep mode. When both enter the sleep mode, most of the internal functional modules and the signal isolator between them will be turned off, which can effectively reduce the standby power consumption of the system. At the same time, based on the correspondence between the sleep control signal and the sleep request signal, the primary controller can also follow the secondary controller to respond to the wake-up demand and enter the wake-up mode, ensuring the rapid wake-up of the system.

[0107] The above embodiments are only illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A control circuit for an isolated switching converter, the isolated switching converter including a primary circuit, a secondary circuit, and a transformer, the transformer being coupled between the primary circuit and the secondary circuit, characterized in that, The control circuit includes: A secondary controller, electrically connected to the secondary circuit, receiving a sleep control signal and generating a sleep request signal according to the sleep control signal. When the sleep control signal is in the first state, the secondary controller enters the sleep mode. When the sleep control signal is in the second state, the secondary controller enters the wake-up mode. A primary controller, electrically connected to the primary circuit, receiving the sleep request signal. When the sleep request signal is in the third state, the primary controller enters the sleep mode. When the sleep request signal is in the fourth state, the primary controller enters the wake-up mode.

2. The control circuit for an isolated switching converter according to claim 1, characterized in that, The secondary controller at least includes a secondary logic circuit, a secondary drive circuit, a detection circuit, and a transmission circuit. The detection circuit is used to detect the secondary winding voltage of the secondary circuit and send it to the secondary logic circuit. The secondary logic circuit generates a secondary control signal and the sleep request signal according to the secondary winding voltage and the sleep control signal. The secondary drive circuit generates a secondary switch drive signal according to the secondary control signal to control the secondary switch in the secondary circuit. The sleep request signal is output to the primary controller through the transmission circuit.

3. The control circuit for an isolated switching converter according to claim 1, characterized in that, The secondary controller at least includes a secondary logic circuit, a detection circuit, and a transmission circuit. The detection circuit is used to detect the secondary winding voltage of the secondary circuit and send it to the secondary logic circuit. The secondary logic circuit generates the sleep request signal according to the secondary winding voltage and the sleep control signal. The sleep request signal is output to the primary controller through the transmission circuit.

4. The control circuit for an isolated switching converter according to claim 1, characterized in that, The control circuit further includes a signal isolator. The signal isolator receives the sleep request signal sent by the secondary controller and isolates and transmits it to the primary controller.

5. The control circuit for an isolated switching converter according to claim 1, characterized in that, The primary controller includes a primary receiving circuit, an undervoltage protection circuit, a primary logic circuit, and a primary drive circuit. The primary receiving circuit receives the sleep request signal and sends it to the primary logic circuit. The undervoltage protection circuit is electrically connected to the primary circuit and is used to detect the supply voltage of the primary controller to obtain an undervoltage protection signal. The primary logic circuit generates a primary control signal according to the sleep request signal and the undervoltage protection signal. The primary drive circuit generates a primary switch drive signal according to the primary control signal to control the primary switch in the primary circuit.

6. The control circuit for an isolated switching converter according to claim 2, characterized in that, When the secondary controller detects that the sleep control signal is in the first state, it turns off the detection circuit, controls the transmission circuit to work periodically, controls the secondary switch to remain off through the secondary switch drive signal, and switches the sleep request signal to the third state. The secondary controller enters the sleep mode.

7. The control circuit for an isolated switching converter according to claim 3, characterized in that, When the secondary controller detects that the sleep control signal is in the first state, it turns off the detection circuit, controls the transmission circuit to work periodically, and switches the sleep request signal to the third state. The secondary controller enters the sleep mode.

8. The control circuit for an isolated switching converter according to claim 5, characterized in that, When the primary controller detects that the sleep request signal is in the third state, it turns off the undervoltage protection circuit and the primary drive circuit, and controls the primary receiving circuit to operate periodically, and the primary controller enters the sleep mode.

9. The control circuit for an isolated switching converter according to claim 2 or 3, characterized in that, When the primary controller and the secondary controller enter the sleep mode, the secondary controller detects the output voltage of the secondary circuit. When the output voltage of the secondary circuit is lower than the first threshold, the secondary controller enters the partial wake-up mode, the secondary logic circuit switches the sleep request signal from the third state to the fifth state, and sends the sleep request signal to the primary controller through the sending circuit.

10. The control circuit for an isolated switching converter according to claim 9, characterized in that, When the primary controller detects that the sleep request signal is in the fifth state, the primary controller enters the partial wake-up mode, turns on the primary drive circuit, and controls the primary switch to act in response to the sleep request signal to supplement the output voltage of the secondary circuit.

11. The control circuit for an isolated switching converter according to claim 9, characterized in that, When the secondary controller enters the partial wake-up mode, the detection circuit is turned on. When it is detected that the secondary winding voltage of the secondary circuit changes corresponding to the sleep request signal, the secondary logic circuit switches the sleep request signal from the fifth state to the third state, and the secondary controller returns to the sleep mode.

12. The control circuit for an isolated switching converter according to claim 2 or 3, characterized in that, When the secondary controller detects that the sleep control signal is in the second state, it turns on the detection circuit and the sending circuit, and switches the sleep request signal to the fourth state, and the secondary controller enters the wake-up mode.

13. The control circuit for an isolated switching converter according to claim 5, characterized in that, When the primary logic circuit detects that the sleep request signal is in the fourth state, it turns on the undervoltage protection circuit, the primary drive circuit and the primary receiving circuit, and controls the primary switch to act through the primary switch drive signal, and the primary controller enters the wake-up mode.

14. The control circuit for an isolated switching converter according to claim 1, characterized in that, The primary controller detects the state of the sleep request signal through one or more of the count value, frequency or encoded information included in the sleep request signal received within a preset time period.

15. A control method for an isolated switching converter, the isolated switching converter comprising a primary circuit, a secondary circuit and a transformer, the transformer being coupled between the primary circuit and the secondary circuit, the primary circuit being controlled by a primary controller, and the secondary circuit being controlled by a secondary controller, characterized in that, The control method includes: The secondary controller receives and responds to a sleep control signal. When the secondary controller detects that the sleep control signal is in the first state, it generates a sleep request signal in the third state according to the sleep control signal, and the secondary controller enters the sleep mode; The primary controller receives and responds to the sleep request signal. When the primary controller detects that the sleep request signal is in the third state, the primary controller enters the sleep mode.

16. The control method for an isolated switching converter according to claim 15, characterized in that, The control method further includes: When the primary controller and the secondary controller enter the sleep mode, detect the output voltage of the secondary circuit; When it is detected that the output voltage of the secondary circuit is lower than the first threshold, the secondary controller enters the partial wake-up mode and switches the sleep request signal from the third state to the fifth state; When the primary controller detects that the sleep request signal is in the fifth state, the primary controller enters a partial wake-up mode, and controls the primary switch to act in response to the sleep request signal to supplement the supply voltage of the primary controller and the output voltage of the secondary circuit, so that the output voltage of the secondary circuit is not lower than the first threshold.

17. The control method for an isolated switching converter according to claim 15, characterized in that, The control method further includes: When the secondary controller detects that the sleep control signal is in the second state, the secondary controller enters a wake-up mode and switches the sleep request signal to the fourth state; When the primary controller detects that the sleep request signal is in the fourth state, the primary controller enters a wake-up mode and controls the primary switch to act.

18. The control method for an isolated switching converter according to claim 15, characterized in that, The secondary controller at least includes a secondary logic circuit, a secondary drive circuit, a detection circuit and a transmission circuit. The detection circuit is used to detect the secondary winding voltage of the secondary circuit and send it to the secondary logic circuit. The control method further includes: The secondary logic circuit generates a secondary control signal and the sleep request signal according to the secondary winding voltage and the sleep control signal. The secondary drive circuit generates a secondary switch drive signal according to the secondary control signal to control the secondary switch in the secondary circuit. The sleep request signal is output to the primary controller through the transmission circuit.

19. The control method for an isolated switching converter according to claim 15, characterized in that, The secondary controller at least includes a secondary logic circuit, a detection circuit and a transmission circuit. The detection circuit is used to detect the secondary winding voltage of the secondary circuit and send it to the secondary logic circuit. The control method further includes: The secondary logic circuit generates the sleep request signal according to the secondary winding voltage and the sleep control signal. The sleep request signal is output to the primary controller through the transmission circuit.

20. The control method for an isolated switching converter according to claim 15, characterized in that, The primary controller includes a primary receiving circuit, an under-voltage protection circuit, a primary logic circuit and a primary drive circuit. The under-voltage protection circuit is electrically connected to the primary circuit and is used to detect the supply voltage of the primary controller to obtain an under-voltage protection signal. The control method further includes: The primary receiving circuit receives the sleep request signal and sends it to the primary logic circuit. The primary logic circuit generates a primary control signal according to the sleep request signal and the under-voltage protection signal. The primary drive circuit generates a primary switch drive signal according to the primary control signal to control the primary switch in the primary circuit.

21. The control method for an isolated switching converter according to claim 18, characterized in that, The control method further includes: When the secondary controller detects that the sleep control signal is in the first state, the detection circuit is turned off, the transmission circuit is controlled to work periodically, the secondary switch is controlled to remain off through the secondary switch drive signal, and the sleep request signal is switched to the third state. The secondary controller enters the sleep mode.

22. The control method for an isolated switching converter according to claim 19, characterized in that, The control method further includes: When the secondary controller detects that the sleep control signal is in the first state, the detection circuit is turned off, the transmission circuit is controlled to work periodically, and the sleep request signal is switched to the third state. The secondary controller enters the sleep mode.

23. The control method for an isolated switching converter according to claim 20, characterized in that, The control method further includes: When the primary controller detects that the sleep request signal is in the third state, the undervoltage protection circuit and the primary drive circuit are turned off, and the primary receiving circuit is controlled to operate periodically, and the primary controller enters the sleep mode.

24. The control method according to claim 15, characterized in that,The primary controller detects the state of the sleep request signal based on one or more of the count value, frequency, or encoded information included in the sleep request signal received within a preset time period.

Images