TWI785731B - Switching power supply and its control chip - Google Patents

Abstract

Provided are a switching power supply and a control chip thereof. The control chip includes a high-voltage N-channel JFET, a current path control module, a pulse width modulation (Pulse Width Modulation, PWM) control module, a power monitoring module, and a Junction Field Effect Transistor (JFET). ) control module. The drain of the high-voltage N-channel JFET is connected to the high-voltage input pin of the control chip, the source is connected to the current path control module, and the gate is connected to the JFET control module. The current path control module is configured to control the turn-on and turn-off of the current path between the high-voltage N-channel JFET and the internal circuit of the control chip. The PWM control module represents the power consumption part in the internal circuit of the control chip, and is configured to control the turn-on and turn-off of the power switch in the switching power supply. The power monitoring module is configured to monitor the power consumption of the PWM control module, and generate a power consumption control signal according to the power consumption of the PWM control module. The JFET control module is configured to control the gate voltage of the high voltage N-channel JFET according to the power control signal.

Description

Switching power supply and its control chip

The invention relates to the field of circuits, in particular to a switching power supply and a control chip thereof.

Switching power supply, also known as switching power supply and switching converter, is a kind of power supply. The function of the switching power supply is to convert a level of voltage into a user-side required voltage or current.

Usually, switching power supply is used for AC to DC (AC/DC) or DC to DC (DC/DC) conversion, and mainly includes the following circuit parts: electromagnetic interference (EMI) filter circuit, rectifier filter circuit, power conversion circuit, pulse Wide modulation (PWM) control circuit, output rectification filter circuit, etc., wherein, the PWM control circuit is mainly realized by the PWM control chip.

A control chip for a switching power supply according to an embodiment of the present invention includes a high-voltage N-channel junction field-effect transistor (JFET), a current path control module, a pulse width modulation (PWM) control module, and a power monitor module, and the JFET control module, wherein: the drain of the high-voltage N-channel JFET is connected to the high-voltage input pin of the control chip, the source is connected to the current path control module, and the gate is connected to the JFET control module; the current path control module is Configured to control the turn-on and turn-off of the current path between the high-voltage N-channel JFET and the internal circuit of the control chip; the PWM control module characterizes the power consumption part in the internal circuit of the control chip, and is configured to control the switching power supply. The power switch is turned on and off; the power monitoring module is configured to monitor the power consumption of the PWM control module, and generates a power consumption control signal according to the power consumption of the PWM control module; and the JFET control module is configured to The control signal controls the gate voltage of the high-voltage N-channel JFET. voltage, thereby controlling the current supplied by the high-voltage N-channel JFET to the internal circuitry of the control die.

According to an embodiment of the present invention, a control chip for a switching power supply is integrated with a high-voltage controllable supply current source (ie, a high-voltage N-channel JFET), and the high-voltage controllable supply current source is adjusted by monitoring the power consumption of the PWM control module The current output can realize the start-up and power supply of the switching power supply. Furthermore, because the high-voltage controllable power supply current source is integrated in the high-voltage input pin of the control chip, the two functions of starting and supplying power to the switching power supply can be realized by using the high-voltage input pin, so the switching power supply according to the embodiment of the present invention The control chip can save the power supply pin of the chip.

A switching power supply according to an embodiment of the present invention includes the above-mentioned control chip for a switching power supply.

Since the control chip for switching power supply according to the embodiment of the present invention can start and supply power to the switching power supply and can save the chip power supply pin, it can save the use of and/or connected to the chip power supply pin when applied to the switching power supply. Or the peripheral circuit used to realize the start-up and power supply of the switching power supply. Therefore, compared with the traditional switching power supply, the cost of the switching power supply according to the embodiment of the present invention is greatly reduced.

N: Signal control high voltage

100,200,300: flyback converter power supply

Vin: input line voltage

R1, R2: resistance

C1: capacitance

I1, I2, I3: control chips

GATE: gate drive pin

M1: Power switch

N _AUX : Auxiliary winding

D1: Diode

HV: High voltage input pin

VDD: chip power supply pin

T: Transformer

302: Current path control module

304: Pulse width modulation (PWM) control module

306: JFET (power monitoring module)

308: JFET control module

B: Current input port (end)

E: current output port (end)

K: switch

D: signal input terminal

306: Power monitoring module

A, C: port

J1: High voltage N-channel junction field-effect transistor (JFFT)

F: power detection signal

Np: Transformer primary winding

Ns: transformer secondary winding

Co: output capacitance

The present invention can be better understood from the following description of specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

Figure 1 shows a system circuit diagram of a traditional flyback converter power supply.

Figure 2 shows a system circuit diagram of a conventional flyback converter power supply.

FIG. 3 shows an example circuit diagram of a flyback converter power supply according to an embodiment of the present invention.

FIG. 4 shows an example circuit implementation of the current path control module 302 shown in FIG. 3 .

FIG. 5 shows an example logic implementation of the power monitoring module 306 shown in FIG. 3 .

FIG. 6 shows an example logic implementation of the JFET control module 308 shown in FIG. 3 .

Features and exemplary implementations of various aspects of the invention are described in detail below example. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by showing examples of the present invention. The present invention is by no means limited to any specific configurations and algorithms set forth below, but covers any modification, substitution and improvement of elements, components and algorithms without departing from the spirit of the invention. In the drawings and the following description, well-known structures and techniques have not been shown in order to avoid unnecessarily obscuring the present invention.

First, with reference to FIG. 1 and FIG. 2 , one or more problems existing in the traditional flyback converter power supply and its control chip will be described.

FIG. 1 shows a system circuit diagram of a conventional flyback converter power supply 100 . After the flyback converter power supply 100 shown in FIG. 1 is powered on, the input line voltage Vin charges the capacitor C1 through the high-voltage start-up resistors R1 and R2, and when the voltage on the capacitor C1 reaches a predetermined value, the flyback converter power supply 100 The start-up process is completed (ie, the flyback converter power supply 100 enters the normal working state from the start-up state). Since there is always a large voltage difference between the two ends of the high-voltage start-up resistors R1 and R2 after the power supply 100 of the flyback converter is powered on, the high-voltage start-up resistors R1 and R2 will continue to consume power and cause power loss, which will reduce the speed of the flyback conversion. system efficiency of the power supply 100. If in order to save the power consumption of the flyback converter power supply 100, a high-voltage start-up resistor with a larger resistance value is selected, the charging time required for the voltage on the capacitor C1 to reach a predetermined value will increase, which will make the start-up of the flyback converter power supply 100 Time increases. In consideration of the system efficiency and start-up time of the flyback converter power supply 100 , the selection of the high voltage start-up resistor will increase the design difficulty of the flyback converter power supply 100 . Meanwhile, the use of the high-voltage start-up resistors R1 , R2 and capacitor C1 will increase the cost of the flyback converter power supply 100 .

In addition, when the flyback converter power supply 100 is in a normal working state, the process of turning on and off the power switch M1 driven by the control chip I1 through the gate driving pin GATE consumes a large amount of current. At this time, the auxiliary winding N _AUX of the transformer T needs to supply power to the control chip I1 through the diode D1 to meet the current consumption requirement of the control chip I1 . Here, the use of auxiliary winding N _AUX and diode D1 also increases the cost of flyback converter power supply 100 .

FIG. 2 shows a system circuit diagram of a conventional flyback converter power supply 200 . After the flyback converter power supply 200 shown in FIG. 2 is powered on, the input line voltage Vin charges the capacitor C1 through the high-voltage start-up circuit integrated between the high-voltage input pin HV of the control chip I2 and the chip power supply pin VDD, and the capacitor C1 When the voltage on C1 reaches a predetermined value, the start-up process of the flyback converter power supply 200 is completed (at the same time, the high-voltage start-up circuit changes from the on state to the off state). Here, the flyback converter power supply 200 does not need a high-voltage start-up resistor, and the high-voltage start-up circuit can change from the on state to the off state after the start-up process of the flyback converter power supply 200 is completed, so the flyback converter power supply 200 is cost and Compared with the flyback converter power supply 100, the power consumption is reduced in both aspects. However, a high-voltage input pin HV is added to the control chip I2, and when the flyback converter power supply 200 is in a normal working state, the auxiliary winding N _AUX of the transformer T still needs to supply power to the control chip I2 to meet the current consumption demand of the control chip I2 . Here too, the use of the auxiliary winding N _AUX and the diode D1 increases the cost of the flyback converter power supply 200 .

In view of one or more problems existing in the flyback converter power supplies 100 , 200 and their control chips I1 , I2 described in conjunction with FIGS. 1 and 2 , a switching power supply and its control chips according to an embodiment of the present invention are proposed. Hereinafter, taking the flyback converter power supply as an example, the switching power supply and its control chip according to the embodiment of the present invention will be described in detail.

FIG. 3 shows an example circuit diagram of a flyback converter power supply 300 according to an embodiment of the present invention. In the flyback converter power supply 300 shown in FIG. 3 , the control chip I3 includes a high-voltage N-channel junction field effect transistor (JFET) J1, a current path control module 302, and a pulse width modulation (PWM) control module. 304, power monitoring module 306, and JFET control module 308, wherein: the drain of the high-voltage N-channel JFET J1 is connected to the high-voltage input pin HV of the control chip I3, the source is connected to the current path control module 302, and the gate is connected to the JFET Control module 308; the current path control module 302 is configured to control the conduction and shutdown of the current path between the high-voltage N-channel JFET J1 and the internal circuit of the control chip I3; the PWM control module 304 represents the interior of the control chip I3 The power consumption part in the circuit, and is configured to control the turn-on and turn-off of the power switch M1 in the flyback converter power supply 300; the power monitoring module 306 is configured to monitor the PWM control module 304 power consumption, and generate a power consumption control signal according to the power consumption of the PWM control module 304; the JFET control module 308 is configured to control the gate voltage of the high-voltage N-channel JFET J1 according to the power consumption control signal, thereby controlling the high-voltage N-channel The current provided by JFET J1 to the internal circuit of the control chip I3 (so that the current supplied by the high-voltage N-channel JFET J1 to the internal circuit of the control chip I3 meets the supply current requirements of the control chip I3 during start-up and normal operation).

In the flyback converter power supply 300 shown in FIG. 3 , since the high-voltage input pin HV of the control chip I3 is connected to the input line voltage Vin, the high-voltage N-channel JFET J1 can use the input line voltage Vin to control the module 302 via the current path. The internal circuits of the control chip I3 are powered.

Here, the control chip I3 is integrated with a high-voltage controllable supply current source (that is, a high-voltage N-channel JFET), and by monitoring the power consumption of the PWM control module (since the PWM control module represents the power consumption in the internal circuit of the control chip I3 part, so monitoring the power consumption of the PWM control module is equivalent to monitoring the power consumption of the control chip I3) to adjust the current output of the high-voltage controllable supply current source, which can realize the startup and power supply of the flyback converter power supply 300. Further, since the high-voltage controllable power supply current source is integrated in the high-voltage input pin HV of the control chip I3, the two functions of starting and supplying power to the flyback converter power supply 300 can be realized by using the high-voltage input pin HV, so the control chip I3 can The chip power supply pin VDD is omitted.

In the flyback converter power supply 300 shown in FIG. 3 , the initial state of the current path control module 302 is set to a conduction state, and the initial state of the JFET control module 308 is set to zero potential. During the start-up process of the flyback converter power supply 300 shown in FIG. 3 , the high-voltage N-channel JFET J1 provides start-up current to the internal circuit of the control chip I3 to boost the power supply voltage of the internal circuit of the control chip I3 .

In some embodiments, when the power supply voltage of the internal circuit of the control chip I3 reaches the startup voltage threshold UVLO_OFF, the current path control module 302 monitors the voltage of its own current input port (terminal) B and current output port (terminal) E , and according to the voltage difference between the current input port (terminal) B and the current output port (terminal) E, the conduction and shutdown of the current path between the high-voltage N-channel JFET J1 and the internal circuit of the control chip I3 are controlled. For example, when the electrical current input port (terminal) and When the voltage difference between the current output ports (terminals) E is lower than the first preset threshold, the current path control module 302 shuts off the current path between the high-voltage N-channel JFET J1 and the internal circuit of the control chip I3 to prevent The internal circuit of the control chip I3 feeds back the current of the high-voltage N-channel JFET J1.

In some embodiments, the current path control module 302 also turns off the high-voltage N-channel JFET J1 and the control chip I3 when the voltage of the current output port E exceeds the second preset threshold (for example, the overvoltage protection voltage Vth_ovp). The current path between the internal circuits of the control chip I3 is used to prevent the internal circuit of the control chip I3 from being damaged due to the high power supply voltage of the control chip I3.

In some embodiments, after the internal circuit of the control chip I3 starts to work, the PWM control module 304 controls the on and off of the power switch M1, and the power monitoring module 306 monitors the current consumption and the power supply voltage of the PWM control module 304 , and at least one of the switch control signal generated by the PWM control module 304 for controlling the on and off of the power switch M1 to monitor the power consumption of the PWM control module 304 . Here, the current consumption and power supply voltage of the PWM control module 304 can represent the static power consumption demand of the control chip I3, and the switch control signal generated by the PWM control module 304 for controlling the on and off of the power switch M1 can represent Controls the dynamic power requirements of chip I3. The power monitoring module 308 can monitor the static power consumption demand of the control chip I3 in real time, and can monitor the switch control signal generated by the PWM control module 304 for controlling the on and off of the power switch M1 to control the subsequent chip I3. The power consumption requirement (that is, the dynamic power consumption requirement) is pre-judged, so as to propose the current output requirement to the JFET control module 308 in advance, so as to avoid the failure of the internal circuit of the control chip I3 due to insufficient power supply response when the drastic dynamic power consumption changes. The drop of the power supply voltage prevents the internal circuit of the control chip I3 from working abnormally.

In some embodiments, the power monitoring module 306 also generates a path control signal according to the power consumption of the PWM control module 304, so that the current path control module 302 controls the connection between the high-voltage N-channel FET J1 and the control chip I3 according to the path control signal. Turns on and off the current path between internal circuits. For example, when the power monitoring module 306 determines that the internal circuit of the control chip I3 has no current input demand according to the power consumption of the PWM control module 304, an instruction current path control module 302 can be generated to turn off the high-voltage N-channel FET J1 and the control chip. Inside the i3 The path of the current path between the circuits turns off the control signal to quickly cut off the current input to the control chip I3, and protect the internal circuit of the control chip I3 from the impact of overcurrent and overvoltage.

FIG. 4 shows an example circuit implementation of the current path control module 302 shown in FIG. 3 . As shown in FIG. 4 , in some embodiments, the current path control module 302 includes a switch K and a switch control submodule. and the voltage at the three terminals of the signal input terminal D to control the closing and opening of the switch K, thereby controlling the conduction and closure of the current path between the high-voltage N-channel JFET J1 and the internal circuit of the control chip I3. For example, the switch control sub-module can control the switch K to turn off when the voltage difference between the current input port (terminal) B and the current output terminal E is lower than the first preset threshold, thereby turning off the high-voltage N-channel JFET J1 and Controls the current paths between the internal circuits of wafer I3. For another example, the switch control sub-module can control the switch K to turn off when the voltage of the current output terminal E exceeds the second preset threshold, so as to cut off the current path between the high voltage N-channel JFET J1 and the internal circuit of the control chip I3. For another example, the switch control sub-module can control the switch K to turn off when receiving the path shutdown control signal from the power monitoring module 306 via the signal input terminal D, thereby turning off the connection between the high-voltage N-channel JFET J1 and the control chip I3 The current path between internal circuits.

FIG. 5 shows an example logic implementation of the power monitoring module 306 shown in FIG. 3 . As shown in FIG. 5 , in some embodiments, the power monitoring module 306 includes a current information processing submodule, a voltage information processing submodule, a switch information processing submodule, and a control signal generation submodule, wherein: the current The information processing sub-module monitors the current consumption of the PWM control module 304 and generates a current consumption characterization signal; the voltage information processing sub-module monitors the power supply voltage of the PWM control module 304 and generates a power supply voltage characterization signal; the switch information processing sub-module monitors The switch control signal used to control the on and off of the power switch M1 generated by the PWM control module 304 generates a switch signal characterization signal; the control signal generation sub-module is based on the current consumption characterization signal, the power supply voltage characterization signal, and the switching signal The characterization signal generates a power consumption control signal.

FIG. 6 shows an example logic implementation of the JFET control module 308 shown in FIG. 3 . As shown in Figure 6, the JFET control module 308 includes a dynamic response control submodule, an adjustment control submodule, a pre-judgment control submodule, and a control signal generation submodule, wherein: the dynamic response control The control sub-module generates a dynamic response control signal according to the power consumption control signal; the adjustment control sub-module generates an adjustment control signal according to the power consumption control signal; the pre-judgment control sub-module generates a pre-judgment control signal according to the power consumption control module; the control signal The generation sub-module generates a gate control signal for controlling the gate voltage of the high-voltage N-channel JFET J1 according to the dynamic response control signal, the adjustment control signal, and the pre-judgment control signal (that is, according to the dynamic response control signal, the adjustment control signal , and the pre-judgment control signal controls the gate voltage of the high-voltage N-channel JFET J1). Here, the dynamic response control submodule, the adjustment control submodule, and the pre-judgment control submodule all receive the power consumption control signal from the power monitoring module 306 through port C, and the control signal generation submodule sends the high-voltage The gate voltage of N-channel JFET J1 outputs the gate control signal.

It can be seen from the above description that the control chip I3 is integrated with a high-voltage controllable power supply current source, and the current output of the high-voltage controllable power supply current source can be adjusted by monitoring the power consumption of the control chip I3, so as to realize the control of the flyback converter power supply 300 Start and power up. Here, because the high-voltage controllable power supply current source is integrated in the high-voltage input pin HV of the control chip I3, the two functions of starting and supplying power to the flyback converter power supply 300 can be realized by using the high-voltage input pin HV, so the control chip I3 can save To chip power supply pin VDD.

In the flyback converter power supply 300 shown in FIG. 3 , since the control chip I3 itself can start and supply power to the flyback converter power supply 300 , compared with the flyback converter power supply 100 shown in FIGS. 1 and 2 and 200, the capacitor C1 and the diode D1 connected between the auxiliary winding N _AUX of the transformer T and the chip power supply pin VDD of the control chip I1/I2 can be omitted, which greatly reduces the cost.

Those skilled in the art should understand that the control chip I3 is not only applicable to the flyback converter power supply 300 , but also applicable to switching power supplies of other architectures such as buck architecture or boost architecture. When the control chip I3 is applied to, for example, a switching power supply of BUCK or BOOST architecture, the use of peripheral circuits connected to the chip power supply pin VDD and/or used to realize the startup and power supply of the switching power supply of BUCK or BOOST architecture can be omitted. Therefore, compared with the traditional switching power supply with BUCK or BOOST architecture, the cost of the switching power supply with BUCK or BOOST architecture according to the embodiment of the present invention is greatly reduced.

The present invention may be embodied in other specific forms without departing from its spirit and essential characteristics. For example, the algorithms described in certain embodiments may be modified without departing from the basic spirit of the invention in terms of system architecture. Therefore, the current embodiments are to be considered in all respects as illustrative rather than restrictive, the scope of the present invention is defined by the appended claims rather than the above description, and what falls within the meanings and equivalents of the claims All changes in scope are thereby embraced within the scope of the invention.

300: flyback converter power supply

Vin: input line voltage

I3: Control chip

GATE: gate drive pin

M1: Power switch

HV: High voltage input pin

T: Transformer

302: Current path control module

304: Pulse width modulation (PWM) control module

306: JFET (power monitoring module)

B: Current input port (end)

E: current output port (end)

D: signal input terminal

A, C: port

J1: High voltage N-channel junction field-effect transistor (JFET)

F: power detection signal

Np: Transformer primary winding

Ns: transformer secondary winding

Co: output capacitance

Claims (8)

A control chip for a switching power supply, including a high-voltage N-channel junction field effect transistor (JFET), a current path control module, a pulse width modulation (PWM) control module, a power monitoring module, and a JFET control module group, wherein: the drain of the high-voltage N-channel JFET is connected to the high-voltage input pin of the control chip, the source is connected to the current path control module, and the gate is connected to the JFET control module; the current path control The module is configured to control the on and off of the current path between the high-voltage N-channel JFET and the internal circuit of the control chip; the PWM control module characterizes the power consumption in the internal circuit of the control chip part, and is configured to control the on and off of the power switch in the switching power supply; the power monitoring module is configured to monitor the power consumption of the PWM control module, and according to the PWM control module Power consumption generates a power consumption control signal; and the JFET control module is configured to control the gate voltage of the high-voltage N-channel JFET according to the power consumption control signal, thereby controlling the high-voltage N-channel JFET to provide control the current of the internal circuit of the wafer, and generate a dynamic response control signal, an adjustment control signal, and a pre-judgment control signal according to the power consumption control signal, and generate a dynamic response control signal, an adjustment control signal, and The predictive control signal controls the gate voltage of the high voltage N-channel JFET. The control chip according to claim 1, wherein the current path control module is further configured to control the high voltage N-channel JFET and the current output port according to the voltage difference between its own current input port and current output port Turning on and off of current paths between internal circuits of the control chip. The control chip according to claim 1, wherein the current path control module is further configured to control the connection between the high-voltage N-channel JFET and the internal circuit of the control chip according to the voltage of its own current output port Turning on and off of the current path between them. The control chip according to claim 1, wherein the power monitoring module is further configured to monitor the current consumption of the PWM control module, the power supply voltage, and the At least one of the switch control signals generated by the PWM control module for controlling the on and off of the power switch monitors the power consumption of the PWM control module. The control chip according to any one of claims 1 to 4, wherein the power monitoring module is further configured to generate a path control signal according to the power consumption of the PWM control module, and the current path control module The group is further configured to control on and off of a current path between the high voltage N-channel FET and an internal circuit of the control wafer according to the path control signal. The control chip according to claim 1, wherein the current path control module is further configured to shut down all the current path control modules when the voltage difference between its own current input port and current output port is lower than a first threshold The current path between the high voltage N-channel JFET and the internal circuitry of the control die. The control chip according to claim 1, wherein the current path control module is further configured to turn off the high-voltage N-channel JFET and the Controls the current path between the internal circuits of the chip. A switching power supply, comprising the control chip for switching power supply according to any one of claims 1 to 7.

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