TW201810906A - Control apparatus used for switch power supply system, and switch power supply system - Google Patents

Abstract

The invention discloses a control apparatus used for a switch power supply system, and the switch power supply system. The control apparatus comprises a first pin, a second pin, a third pin, a fourth pin, a clamping module connected between the first pin and the ground, a diode connected between the first pin and the second pin, an apparatus power switch connected between the second pin and the third pin, and a first switch connected between the second pin and the fourth pin, the first pin is connected with input voltage of the control apparatus through a first resistor, connected with the ground through a first capacitor, and connected with a grid electrode of a system power switch of the switch power supply system, the second pin is connected with a source electrode of the system power switch, the third pin is connected with the ground through a second resistor, and the fourth pin is connected with the ground through a second capacitor. When the voltage of the second capacitor is higher than an under-voltage protection voltage threshold, the control apparatus controls the switch-on and switch-off of the system power switch through control of switch-on and switch-off of the apparatus power switch, and charging and discharging of the second capacitor are controlled through the control of the switch-on and switch-off of the first switch.

Description

Control device for switching power supply system and switching power supply system

The present invention relates to the field of circuits, and more particularly, to a control device for a switching power supply system and a switching power supply system.

Source drive power switching power supply systems are widely used in light emitting diode (LED) lighting, mobile phone charging and other fields due to their simple structure and fast system startup.

Figure 1 is a circuit diagram of a typical BUCK-BOOST source drive power switching power supply system. In the system shown in Figure 1, after the AC input voltage V _AC is rectified by the full-wave rectifier BD1, a voltage Vbulk is generated on the capacitor C1; the GATE pin of the Pulse Width Modulation (PWM) controller passes The resistor R1 is connected to the voltage Vbulk and connected to the ground through the capacitor C4. The resistor R1 and the capacitor C4 together form an RC charging circuit. During the voltage Vbulk to charge the capacitor C4 through the resistor R1, the voltage at the GATE pin of the PWM controller V _GATE gradually increases; there is a clamp element circuit inside the PWM controller to maintain the voltage V _GATE at a high potential; when the gate voltage (ie, the voltage V _GATE ) of the power switch M1 and the source voltage (ie, the PWM control When the voltage difference between the voltage V _SW at the SW pin of the converter is higher than the turn-on threshold of the power switch M1, the power switch M1 is turned on and forms a source follower; at this time, the control SW pin inside the PWM controller reaches When the power supply path of the VDD pin is connected and the open switch is closed, the PWM controller starts to charge the capacitor C3; when the voltage V _DD at the VDD pin of the PWM controller (that is, the power supply voltage of the PWM controller) is higher than the PWM The internal setting of the controller Protected voltage threshold, PWM control is started by controlling the power switch SW pin M1 is turned on and off, while the control pin to the SW power supply path VDD pin connection and disconnection of the switch is turned off, the voltage V _DD by a secondary Group winding L2 is provided.

In various conventional source-driven power switching power supply systems including the source-driven power switching power supply system of the BUCK-BOOST architecture shown in FIG. 1, additional power supply elements such as the auxiliary group winding L2 are required. The device powers a control device such as a PWM controller, so there are disadvantages such as high cost and low power supply efficiency.

The invention provides a novel control device for a switching power supply system and a switching power supply system.

A control device for a switching power supply system according to an embodiment of the present invention includes a first pin, a second pin, a third pin, a fourth pin, and a clamp element connected between the first pin and the ground. A module, a diode connected between the first pin and the second pin, a device power switch connected between the second pin and the third pin, and a device connected between the second pin and the fourth pin A first switch between the pins, wherein the first pin is connected to the input voltage of the control device through a first resistor, connected to ground through a first capacitor, and connected to a gate of a system power switch in a switching power supply system, and The two pins are connected to the source of the system power switch, the third pin is connected to the ground through a second resistor, and the fourth pin is connected to the ground through a second capacitor. After the control device is powered on, the voltage at the first pin gradually increases, it is clamped by the clamp module, and when the system power switch is turned on, the second pin and the fourth pin are connected to the second pin. Capacitor charging; when the voltage on the second capacitor is higher than the undervoltage protection voltage threshold of the control device, the control device controls the on and off of the system power switch by controlling the on and off of the power switch of the control device, and by controlling the first The switch is closed and opened to control the charging and discharging of the second capacitor.

A control device for a switching power supply system according to an embodiment of the present invention includes a first pin, a second pin, a third pin, a fourth pin, and a clamp element connected between the first pin and the ground. A module, a diode connected between a first pin and a second pin, a diode connected between a first pin and a fourth pin, and a second pin and a third pin And a first switch connected between the second pin and the fourth pin, wherein the first pin is connected to the gate of the system power switch in the switching power supply system, and the second pin And system power switch The third pin is connected to ground through a second resistor, the fourth pin is connected to the input voltage of the control device through a first resistor, and is connected to ground through a first capacitor. After the control device is powered on, the voltage at the first pin gradually increases following the voltage at the fourth pin, is clamped by the clamp module, and passes through the second pin and the first pin when the system power switch is turned on. Four pins charge the first capacitor; when the voltage on the second capacitor is higher than the undervoltage protection voltage threshold of the control device, the control device controls the on and off of the system power switch by controlling the on and off of the power switch of the control device , And control the charging and discharging of the first capacitor by controlling the opening and closing of the first switch.

A switching power supply system according to an embodiment of the present invention includes the control device as described above.

In a switching power supply system including a control device according to an embodiment of the invention, the power supply voltage to the control device is generated by turning on and off the power switch of the control system, so no additional peripheral components or transformer windings need to be added. This makes the system cost of the switching power supply system including the control device according to the embodiment of the present invention low, and the power conversion efficiency is high.

BD1‧‧‧full wave rectifier

Drain‧‧‧Drain voltage

U1‧‧‧ Clamp Module

Tblank‧‧‧Mask time

U2‧‧‧Drive Module

Clamp‧‧‧Clamp

U3‧‧‧ Detection Module

FUSE‧‧‧Fuse

U4‧‧‧ Comparator

V _AC ‧‧‧ AC input voltage

RC‧‧‧Charging circuit

PWM‧‧‧Pulse Width Modulation

L2‧‧‧ auxiliary winding

D1, D2, D3‧‧‧ diodes

Vref‧‧‧Reference voltage

300, 500, 600‧‧‧ control devices

R1, R2‧‧‧ resistance

C1, C3, C4, C5‧‧‧ capacitors

K1, K2‧‧‧ switches

GATE, SW, VDD, CS‧‧‧ pins

M1, M2‧‧‧ Power Switch

Vbulk, V _GATE , V _SW , V _DD , V _CS ‧‧‧ Voltage

Other features, objects, and advantages of the present invention will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings, in which the same or similar reference numerals denote the same or similar features.

FIG. 1 is a circuit diagram of a typical BUCK-BOOST architecture source drive power switching power supply system; FIG. 2 is a circuit diagram of a switching power supply system according to an embodiment of the present invention; and FIG. The circuit diagram of the control device of the switching power supply system shown in Fig. 2; Fig. 4 is the PWM signal, the voltage signal at the CS pin, the voltage signal at the SW pin, and Timing chart of a control signal of the switch K1; FIG. 5 is a circuit diagram of a control device for a switching power supply system shown in FIG. 2 according to a second embodiment of the present invention; and Fig. 6 is a circuit diagram of a control device for a switching power supply system shown in Fig. 2 according to a third embodiment of the present invention.

Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided to make the present invention more comprehensive and complete, and to fully convey the concept of the example embodiments to Those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus their detailed descriptions will be omitted.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of the embodiments of the present invention. However, those skilled in the art will realize that the technical solutions of the present invention may be practiced without one or more of the specific details, or other methods, components, materials, etc. may be adopted. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring the main technical idea of the present invention.

In view of the foregoing, the present invention proposes a novel control device and control method for a switching power supply system, and a switching power supply system. Hereinafter, a control device and a control method for a switching power supply system and a switching power supply system according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a circuit diagram of a switching power supply system according to an embodiment of the present invention. With reference to Figures 1 and 2, it can be seen that the switching power supply system shown in Figure 2 is different from the switching power supply system shown in Figure 1 in that the supply voltage V _DD of the PWM controller is generated internally by the PWM controller. No additional transformer windings are required. The control principle for the switching power supply system shown in FIG. 2 will be described in detail below with reference to FIGS. 3 to 5.

It should be noted that the present invention is not limited to the switching power supply system of the BUCK-BOOST architecture. The control principles described below are also applicable to switching power supply systems of the architectures such as FLY-BUCK, BUCK, and BOOST. Therefore, the components related to the system architecture of the switching power supply system are no longer shown in Figs. 3 and 5. Instead, they are rectified. To the voltage Vbulk and the drain voltage Drain of the power switch M1.

Fig. 3 is a circuit diagram of a control device for the switching power supply system shown in Fig. 2 according to the first embodiment of the present invention. As shown in FIG. 3, the control device 300 includes a clamp unit U1, a drive module U2, a diode D2, a diode D3, a switch K1, and a power switch M2. The external connection relationship of the control device 300 is as follows: The GATE pin of the control device 300 is connected to the voltage Vbulk through a resistor R1 and to the ground through a capacitor C4. The resistor R1 and the capacitor C4 together form an RC charging circuit; the GATE pin of the control device 300 is also connected to the gate of the power switch M1; The SW pin of the control device 300 is connected to the source of the power switch M1; the CS pin of the control device 300 is connected to ground through a resistor R2; and the VDD pin of the control device 300 is connected to ground through a capacitor C5. Here, the switch K1 is a switch that controls the connection and disconnection of the power supply path of the SW pin to the VDD pin in the control device 300, and its initial state is a closed state.

After the switching power supply system including the control device 300 is powered on, the voltage Vbulk charges the capacitor C4 through the resistor R1, so that the voltage V _GATE at the GATE pin of the control device 300 gradually increases; the clamp unit module inside the control device 300 The high potential of the U1 sustain voltage V _GATE is not higher than the clamp voltage; when the gate voltage (ie, the voltage V _GATE ) of the power switch M1 and the source voltage (ie, the voltage V _SW at the SW pin of the control device 300) ) When the voltage difference between them is higher than the turn-on threshold of the power switch M1, the power switch M1 is turned on and forms a source follower; at this time, due to the connection between the control SW pin to the VDD pin power supply path in the control device 300 and The open switch K1 is closed, so the control device 300 starts to charge the capacitor C5; when the voltage V _DD at the VDD pin of the control device 300 (ie, the power supply voltage of the control device 300) is higher than the internal setting of the control device 300 When the undervoltage protection voltage threshold is reached, the control device 300 starts to generate a PWM signal; the drive module U2 controls the on and off of the power switch M2 based on the PWM signal, thereby controlling the on and off of the power switch M1; the switch K1 is based on the PWM signal. Closing or opening to the signal.

Here, when the PWM signal is at the high level, the power switch M2 is turned on and the switch K1 is turned off; when the PWM signal is at the low level, the power switch M2 is turned off and the switch K1 is closed; when the PWM signal changes from the low level to the high level, the power switch M2 From off to on On, switch K1 changes from closed to open. In order that the main charge of the ringing voltage generated at the SW pin of the control device 300 when the power switch M2 changes from on to off is provided to the GATE pin of the control device 300, the switch is switched when the PWM signal changes from a high level to a low level K1 will not change from open to closed immediately, but will change from open to closed after a mask time.

FIG. 4 is a timing chart of the PWM signal, the voltage signal at the CS pin, the voltage signal at the SW pin, and the control signal of the switch K1 in the control device shown in FIG. 3. Combining Figures 3 and 4 shows:

When the PWM signal is at a high level, the power switch M2 is turned on, the switch K1 is turned off, and the voltage V _SW at the SW pin of the control device 300 is pulled down to a lower level by the power switch M2, that is, at the CS pin of the control device 300 Voltage V _CS , diode D2 and diode D3 are in the off state, the voltage V _DD at the VDD pin of the control device 300 is held by the capacitor C5, and the voltage V _GATE at the GATE pin of the control device 300 is held by the capacitor C4 remains. At this time, since the voltage difference between the gate voltage V _GATE and the source voltage V _SW of the power switch M1 is higher than the turn-on threshold of the power switch M1, the power switch M1 is turned on.

When the PWM signal changes from a high level to a low level, the power switch M2 is turned off, the switch K1 is still turned off, and a high ringing voltage due to LC resonance exists at the SW pin of the control device 300; at this time, because the switch K1 is still Opening, the ringing voltage is clamped by the diode D2 between the clamp unit U1 and SW pins and the GATE pin in the control device 300; the excess charge corresponding to the ringing voltage flows into the GATE control device 300 Capacitor C4 connected to the pin; part of the ringing voltage that is higher than the clamp unit voltage of clamp unit U1 is discharged to ground by clamp unit U1, and the voltage V _GATE at the GATE pin of control device 300 is maintained at the clamp Near the clamp voltage of the bit module U1. At this time, since the voltage difference between the gate voltage V _GATE and the source voltage V _SW of the power switch M1 is lower than the turn-on threshold of the power switch M1, the power switch M1 is turned off.

When the PWM signal changes from high level to low level for a period of time, the power switch M2 is still turned off and the switch K1 is closed. Due to the voltage V _SW at the SW pin of the control device 300 and the voltage V at the VDD pin of the control device 300 The voltage difference between _DD is larger than the conduction threshold of diode D3, so diode D3 is turned on, and the voltage V _SW at the SW pin of control device 300 is clamped by diode D3 to VDD of control device 300. Near the voltage V _DD at the pin; when the power supply voltage (ie, the voltage V _DD ) of the control device 300 drops lower due to the power supply to the control device 300, the gate voltage V _GATE and the source voltage V of the power switch M1 The voltage difference between _SW is higher than the turn-on threshold of the power switch M1. The power switch M1 is turned on and forms a source follower; the power switch M1 sends its gate voltage V _GATE to the VDD pin of the control device 300 to make the voltage V _DD remained stable.

Specifically, the voltage V _DD at the VDD pin of the control device 300 can be expressed by the following equation: VDD = V _GATE - V _GS - V _D3

Among them, V _GATE is the voltage at the GATE pin of the control device 300 and is equal to the clamp element voltage of the clamp element module U1, V _GS is the conduction threshold of the power switch M1, and V _D3 is the conduction threshold of the diode D3.

In the control device 300 shown in FIG. 3, the power supply to the control device 300 is realized by internal control of the control device 300, and no external auxiliary winding is required. In order that the main charge of the ringing voltage generated at the SW pin of the control device 300 when the power switch M2 is turned off is provided to the GATE pin of the control device 300, the switch is controlled when the PWM signal changes from a high level to a low level K1 closes after the set mask time Tblank.

Fig. 5 is a circuit diagram of a control device for a switching power supply system shown in Fig. 2 according to a second embodiment of the present invention. As shown in FIG. 5, the control device 500 includes a switch K2 and a detection unit in addition to the clamp unit U1, the drive module U2, the diode D2, the diode D3, the switch K1, and the power switch M2. Module U3 and comparator U4; the external connection relationship of the control device 500 is as follows: The GATE pin of the control device 500 is connected to the voltage Vbulk through a resistor R1 and to the ground through a capacitor C4, and the resistor R1 and the capacitor C4 together form an RC charging circuit The GATE pin of the control device 500 is also connected to the gate of the power switch M1; the SW pin of the control device 500 is connected to the source of the power switch M1; the CS pin of the control device 500 is connected to ground through the resistor R2; the control device 500 VDD pin through capacitor C5 Connected to ground. Here, the switch K1 is a switch for connecting and disconnecting the power supply path of the control SW pin to the VDD pin in the control device 500, and its initial state is a closed state; the switch K2 is a control GATE pin in the control device 500 to VDD The initial state of the power supply switch of the pin is the off state.

After the switching power supply system including the control device 500 is powered on, the voltage Vbulk charges the capacitor C4 through the resistor R1, so that the voltage V _GATE at the GATE pin of the control device 500 gradually increases; the clamp element mode inside the control device 500 Group U1 maintains the high potential of the voltage V _GATE not higher than the clamp voltage; when the gate voltage (ie, voltage V _GATE ) of the power switch M1 and the source voltage (ie, at the SW pin of the control device 500 When the voltage difference between the voltages V _SW ) is higher than the turn-on threshold of the power switch M1, the power switch M1 is turned on and forms a source follower; at this time, because the power supply path from the control SW pin to the VDD pin in the control device 500 is internal The connected and disconnected switch K1 is closed, so the control device 500 starts to charge the capacitor C5; when the voltage V _DD at the VDD pin of the control device 500 (ie, the power supply voltage of the control device 500) is higher than the control device 500 When the undervoltage protection voltage threshold is set internally, the control device 500 starts to generate a PWM signal; the drive module U2 controls the on and off of the power switch M2 based on the PWM signal, thereby controlling the on and off of the power switch M1; the switch K1 is based on P The reverse signal of the WM signal is closed or opened.

Here, when the PWM signal is at the high level, the power switch M2 is turned on and the switch K1 is turned off; when the PWM signal is at the low level, the power switch M2 is turned off and the switch K1 is closed; when the PWM signal changes from the low level to the high level, the power switch M2 From off to on, switch K1 changes from closed to open. In order for the main charge of the ringing voltage generated at the SW pin of the control device 500 to be supplied to the GATE pin of the control device 500 when the power switch M2 is turned off, the switch K1 is not immediately changed when the PWM signal changes from a high level to a low level It changes from open to closed, but only after a period of masking time.

When the PWM signal is at a high level, the power switch M2 is turned on, the switch K1 is turned off, and the voltage V _SW at the SW pin of the control device 500 is pulled down to a lower level by the power switch M2, that is, at the CS pin of the control device 500 Voltage V _CS , so diode D2 and diode D3 are in the off state. The voltage V _DD at the VDD pin of the control device 500 is maintained by the capacitor C5, and the voltage V _GATE at the GATE pin of the control device 500 is Capacitor C4 remains. At this time, since the voltage difference between the gate voltage V _GATE and the source voltage V _SW of the power switch M1 is higher than the turn-on threshold of the power switch M1, the power switch M1 is turned on.

When the PWM signal changes from a high level to a low level, the power switch M2 is turned off, the switch K1 is still turned off, and a high ringing voltage due to LC resonance exists at the SW pin of the control device 500; at this time, because the switch K1 is still Opening, the ringing voltage is clamped by the diode D2 between the clamp unit U1 and SW pins and the GATE pin inside the control device 500; the excess charge corresponding to the ringing voltage flows into the GATE control device 500 The capacitor C4 connected to the pin; the detection module U3 detects the voltage V _GATE at the GATE pin of the control device 500 and outputs the detection result to the comparator U4; when the voltage V _{GATE is} higher than the reference voltage Vref The switch K2 connected to the VDD pin of the control device 500 is closed, and the switch K2 connected to the VDD pin of the control device 500 is opened when the voltage V _{GATE is} lower than the reference voltage Vref, so that the ringing voltage is higher than the reference voltage A part of the excess charge corresponding to the control device 500 is provided to the capacitor C5 through the pin VDD of the control device 500, thereby improving the power supply efficiency; the voltage V _GATE at the GATE pin of the control device 500 is maintained near the voltage of the clamp unit U1 . At this time, since the voltage difference between the gate voltage V _GATE and the source voltage V _SW of the power switch M1 is lower than the turn-on threshold of the power switch M1, the power switch M1 is turned off. Here, the reference voltage Vref may be a predetermined voltage larger than the voltage V _DD at the VDD pin of the control device 500 and smaller than the clamp element voltage of the clamp element module U1.

When the PWM signal changes from high level to low level for a period of time, the power switch M2 is still turned off and the switch K1 is closed. Due to the voltage V _SW at the SW pin of the control device 500 and the voltage V at the VDD pin of the control device 500 The voltage difference between _DD is greater than the conduction threshold of diode D3, so diode D3 is turned on, and the voltage V _SW at the SW pin of control device 500 is pulled down by diode D3 to the VDD pin of control device 500 Near the voltage V _{DD of the} power switch; when the power supply voltage (ie, the voltage V _DD ) of the control device 500 is lowered due to the power supplied to the control device 500, the gate voltage V _{GATE of the} power switch M1 and the source voltage V _SW The voltage difference between them is higher than the turn-on threshold of the power switch M1. The power switch M1 is turned on and forms a source follower; the power switch M1 sends its gate voltage V _GATE to the VDD pin of the control device 500 to maintain the voltage V _DD At a stable level.

It can be seen that such a control device (for example, control device 300) for a switching power supply system is described with reference to FIGS. 3 to 5 and includes a first pin (for example, a GATE pin) and a second pin (for example, a GATE pin). For example, the SW pin), the third pin (for example, the CS pin), the fourth pin (for example, the VDD pin), and a clamp module (for example, Clamping module U1), diode (e.g., diode D2) connected between the first and second pins, device power connected between the second and third pins A switch (for example, power switch M2) and a first switch (for example, switch K1) connected between the second pin and the fourth pin, wherein the first pin passes a first resistor (for example, resistor R1) Connected to an input voltage (eg, voltage Vbulk) of the control device, connected to ground through a first capacitor (eg, capacitor C4), and connected to a gate of a system power switch (eg, power switch M1) in a switching power supply system, The second pin is connected to the source of the system power switch, the third pin is connected to ground through a second resistor (for example, resistor R2), and the fourth pin A second capacitor connected to ground via (e.g., capacitors C5). After the control device is powered on, the voltage at the first pin (for example, the voltage V _GATE ) gradually increases, is clamped by the clamp module, and passes through the second pin and the fourth pin when the system power switch is turned on. The pin charges the second capacitor; when the voltage on the second capacitor is higher than the undervoltage protection voltage threshold of the control device, the control device controls the on and off of the system power switch by controlling the on and off of the power switch of the control device Turn off, and control the charging and discharging of the second capacitor by controlling the closing and opening of the first switch. Here, the control device controls on and off of the power switch of the device based on a first control signal (for example, a PWM signal), and controls closing and opening of the first switch based on a reverse signal of the first control signal.

In some embodiments, the control device (for example, control device 500) may further include a second switch (for example, switch K2) connected between the first pin and the fourth pin, and detect The voltage detection module (for example, the detection module U3), and a comparison result based on the voltage detected by the detection module and a predetermined voltage (for example, the reference voltage Vref) A comparator (for example, comparator U4) that generates a second control signal that controls the closing and opening of the second switch. Wherein, when the voltage detected by the detection module is higher than the predetermined voltage, the second control signal is at a high level and the second switch is closed; when the voltage detected by the detection module is lower than the predetermined voltage, the second control The signal is low and the second switch is open.

Fig. 6 is a circuit diagram of a control device for a switching power supply system shown in Fig. 2 according to a third embodiment of the present invention. As shown in FIG. 6, the control device 600 includes, in addition to the clamp unit U1, the drive module U2, the detection module U3, the comparator U4, the diode D2, the diode D3, the switch K1, the switch K2, And the power switch M2 further includes a diode D4; and the external connection relationship of the control device 600 is as follows: the VDD pin of the control device 600 is connected to the voltage Vbulk through the resistor R1 and connected to the ground through the capacitor C5, and the resistor R1 and the capacitor C4 together Form RC charging circuit; GATE pin of control device 600 is connected to the gate of power switch M1; SW pin of control device 600 is connected to the source of power switch M1; CS pin of control device 600 is connected to ground through resistor R2 . Here, the switch K1 is a switch for controlling the connection and disconnection of the power supply path of the SW pin to the VDD pin in the control device 600, and its initial state is a closed state; the switch K2 is a control GATE pin in the control device 600 to VDD The initial state of the power supply switch of the pin is the off state.

After the switching power supply system including the control device 600 is powered on, the voltage Vbulk charges the capacitor C5 through the resistor R1, so that the voltage V _DD at the VDD pin of the control device 600 gradually increases; when the VDD pin of the control device 600 is at When the voltage V _DD (ie, the power supply voltage of the control device 600) is higher than the undervoltage protection voltage threshold set in the control device 600, the control device 600 starts to generate a PWM signal; the drive module U2 controls the conduction of the power switch M2 based on the PWM signal And switch off, thereby controlling the on and off of the power switch M1; the switch K1 is turned on or off based on the reverse signal of the PWM signal.

Here, when the PWM signal is at the high level, the power switch M2 is turned on and the switch K1 is turned off; when the PWM signal is at the low level, the power switch M2 is turned off and the switch K1 is closed; when the PWM signal changes from the low level to the high level, the power switch M2 From off to on, switch K1 changes from closed to open. To enable the control device 600 when the power switch M2 is turned off The main charge of the ringing voltage generated at the SW pin is provided to the GATE pin of the control device 600. When the PWM signal changes from a high level to a low level, the switch K1 does not immediately change from open to closed but passes through a mask It will not change from open to closed after time.

Inside the control device 600, the VDD pin and the GATE pin are connected through the diode D4, and the voltage V _GATE at the GATE pin of the control device 600 is controlled by the voltage V _DD at the VDD pin during the startup phase. Specifically, the voltage V _GATE can be expressed by the equation V _GATE = V _DD -D4, where D4 represents the turn-on threshold of the diode D4.

When the PWM signal is at a high level, the power switch M2 is turned on, the switch K1 is turned off, and the voltage V _SW at the SW pin of the control device 600 is pulled down to a lower level by the power switch M2, that is, at the CS pin of the control device 600 The voltage V _CS . At this time, the voltage V _DD at the VDD pin of the control device 600 is held by the capacitor C5, and the voltage V _GATE at the GATE pin of the control device 600 is clamped to the voltage V _DD by the diode D4, and the diode D2 And D3 are off. Since the voltage difference between the gate voltage V _GATE and the source voltage V _SW of the power switch M1 is greater than the turn-on threshold of the power switch M1, the power switch M1 is turned on.

When the PWM signal changes from a high level to a low level, the power switch M2 is turned off, the switch K1 is still turned off, and a high ringing voltage due to LC resonance exists at the SW pin of the control device 600; at this time, because the switch K1 is still Opening, the ringing voltage is clamped by the diode D2 between the clamp unit U1 and SW pins and the GATE pin in the control device 600; the excess charge corresponding to the ringing voltage flows into the GATE control device 600 feet; V _GATE voltage detection module detects U3 at pin GATE control device 600; comparator U4 when the voltage at pin V _GATE GATE control device 600 is lower than the reference voltage Vref, the control device 600 control The switch K2 connected to the VDD pin is turned off, the voltage V _GATE at the GATE pin of the control device 600 is clamped by the diode D4 near the voltage V _DD at the VDD pin of the control device 600, and the capacitor C5 is discharged to When the voltage V _GATE at the GATE pin of the control device 600 is higher than the reference voltage Vref, the comparator U4 controls the switch K2 connected to the VDD pin of the control device 600 to close, so as to close the control device 600. the voltage V _GATE GATE pin charge director The control device 600 of the VDD pin, charging the capacitor C5, thereby improving the power supply efficiency; voltage V _GATE GATE pin if the control means 600 continues to rise to a higher element module U1 will be clamped thereto with clamp forceps Near the bit voltage. At this time, since the voltage difference between the gate voltage V _GATE and the source voltage V _SW of the power switch M1 is lower than the turn-on threshold of the power switch M1, the power switch M1 is turned off. Here, the reference voltage Vref may be a predetermined voltage that is greater than the voltage V _DD at the VDD pin of the control device 600 and smaller than the clamp voltage of the clamp module U1.

When the PWM signal changes from high level to low level for a period of time, the power switch M2 is still turned off, and the switch K1 is closed. When the voltage V _DD at the VDD pin of the control device 600 is lowered due to the power supply to the control device 600 The voltage difference between the voltage V _SW at the SW pin of the control device 600 and the voltage V _DD at the VDD pin of the control device 600 is greater than the turn-on threshold of the diode D3, and the diode D3 is turned on. The control device 600 The voltage V _SW at the SW pin is pulled down by the diode D3 to the voltage V _DD at the VDD pin of the control device 600. The voltage difference between the gate voltage V _GATE and the source voltage V _{SW of the} power switch M1 The value is higher than the turn-on threshold of the power switch M1, the power switch M1 is turned on and forms a source follower; the power switch M1 sends its gate voltage V _GATE to the VDD pin of the control device 600 to maintain the voltage V _DD at a stable level .

It can be seen that such a control device (for example, the control device 600) is described with reference to FIG. 6 and includes a first pin (for example, a GATE pin), a second pin (for example, a SW pin), and a third pin. Pin (for example, CS pin), fourth pin (for example, VDD pin), a clamp module (for example, clamp module U1) connected between the first pin and ground, connected to A diode (for example, diode D2) between the first pin and the second pin, a diode (for example, diode D4) connected between the first pin and the fourth pin, A device power switch (for example, power switch M2) connected between the second pin and the third pin, and a first switch (for example, switch K1) connected between the second pin and the fourth pin, Wherein: the first pin is connected to the gate of a system power switch (for example, power switch M1) in the switching power supply system, the second pin is connected to the source of the system power switch, and the third pin is connected through a second resistor (for example, , Resistor R2) is connected to ground, and the fourth pin passes the first resistor (for example, resistor R1) It is connected to the input voltage of the control device and is connected to the ground through a first capacitor (for example, capacitor C5). After the control device is powered on, the voltage at the first pin gradually increases following the voltage at the fourth pin, is clamped by the clamp module, and passes through the second pin and the first pin when the system power switch is turned on. Four pins charge the first capacitor; when the voltage on the second capacitor is higher than the undervoltage protection voltage threshold of the control device, the control device controls the on and off of the system power switch by controlling the on and off of the power switch of the control device , And control the charging and discharging of the first capacitor by controlling the opening and closing of the first switch.

In some embodiments, the control device (for example, control device 600) may further include a second switch (for example, switch K2) connected between the first pin and the fourth pin, and detect The voltage detection module (for example, the detection module U3), and the control of closing and opening the second switch is generated based on a comparison result between the voltage detected by the detection module and a predetermined voltage (for example, the reference voltage Vref). Comparator (eg, comparator U4) of the second control signal. Wherein, when the voltage detected by the detection module is higher than the predetermined voltage, the second control signal is at a high level and the second switch is closed; when the voltage detected by the detection module is lower than the predetermined voltage, the second control The signal is low and the second switch is open.

In various conventional source-driven power switching power supply systems including the source-driven power switching power supply system of the BUCK-BOOST architecture shown in FIG. 1, additional power supply elements such as the auxiliary group winding L2 are required. The device powers a control device such as a PWM controller, so there are disadvantages such as high cost and low power supply efficiency.

The control device according to the embodiment of the present invention can be widely applied to a plurality of switching power supply fields such as a power adapter using a source switch control, a mobile phone charger, and LED lighting.

However, it needs to be clear that the present invention is not limited to the specific configurations and processes described above and shown in the drawings. And, for the sake of brevity, detailed descriptions of known method technologies are omitted here. In the above embodiments, several specific steps have been described and shown as examples. However, the method of the present invention is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications, and additions after understanding the spirit of the present invention. Or change the order between steps.

The present invention may be implemented in other specific forms without departing from the spirit and essential characteristics thereof. For example, the algorithms described in particular embodiments may be modified without the system architecture departing from the basic spirit of the invention. Therefore, the current embodiment is considered in all aspects as exemplary rather than limiting, the scope of the present invention is defined by the scope of the attached patent application rather than the above description, and the meanings and equivalents falling within the scope of the patent application All changes within the scope of the substance are thus included in the scope of the present invention.

300‧‧‧Control device

R1, R2‧‧‧ resistance

U1‧‧‧ Clamp Module

M1, M2‧‧‧ Power Switch

U2‧‧‧Drive Module

D2, D3‧‧‧ diodes

K1‧‧‧ switch

C4, C5‧‧‧ capacitor

Drain‧‧‧Drain voltage

Vbulk‧‧‧Voltage

PWM‧‧‧Pulse Width Modulation

Clamp‧‧‧Clamp

GATE, SW, VDD, CS‧‧‧ pins

Claims (11)

A control device for a switching power supply system includes a first pin, a second pin, a third pin, a fourth pin, a clamp element module connected between the first pin and ground, A diode connected between the first pin and the second pin, a device power switch connected between the second pin and the third pin, and a device connected between the first pin and the third pin A first switch between two pins and the fourth pin, wherein the first pin is connected to the input voltage of the control device through a first resistor, connected to ground through a first capacitor, and connected to all The gate connection of the system power switch in the switching power supply system, the second pin is connected to the source of the system power switch, the third pin is connected to ground through a second resistor, and the fourth pin is connected through The second capacitor is connected to ground. After the control device is powered on, the voltage at the first pin gradually increases, is clamped by the clamp module, and is turned on when the system power switch is turned on. The second capacitor is charged via the second pin and the fourth pin. When the voltage on the capacitor is higher than the under-voltage protection voltage threshold of the control device, the control device controls the on and off of the system power switch by controlling the on and off of the power switch of the device, and The closing and opening of the first switch controls the charging and discharging of the second capacitor. The control device according to item 1 of the scope of patent application, wherein the control device controls the on and off of the power switch of the device based on a first control signal, and controls an office based on a reverse signal of the first control signal. The closing and opening of the first switch are described. The control device according to item 2 of the scope of patent application, wherein the first switch changes from closed to open when the first control signal changes from a low level to a high level, and when the first control signal changes from When the high level becomes the low level, it changes from open to closed after a mask time. The control device according to item 1 of the scope of patent application, further comprising a second switch connected between the first pin and the fourth pin, and a detection device for detecting a voltage at the first pin. A test module, and a comparator that generates a second control signal that controls the closing and opening of the second switch based on a comparison result between the voltage detected by the detection module and a predetermined voltage, wherein When the voltage detected by the detection module is higher than the predetermined voltage, the second control signal is at a high level, the second switch is closed, and when the voltage detected by the detection module is low At the predetermined voltage, the second control signal is at a low level, and the second switch is turned off. The control device according to item 4 of the scope of patent application, wherein the predetermined voltage is greater than the voltage at the fourth pin and smaller than the clamp element voltage of the clamp element module. A control device for a switching power supply system includes a first pin, a second pin, a third pin, a fourth pin, a clamp element module connected between the first pin and ground, A diode connected between the first pin and the second pin, a diode connected between the first pin and the fourth pin, connected to the second pin A device power switch between the pin and the third pin, and a first switch connected between the second pin and the fourth pin, wherein the first pin and the fourth pin The gate of the system power switch in the switching power supply system is connected, the second pin is connected to the source of the system power switch, the third pin is connected to ground through a second resistor, and the fourth pin is connected through the first A resistor is connected to the input voltage of the control device and is connected to ground through a first capacitor. After the control device is powered on, the voltage at the first pin gradually follows the voltage at the fourth pin. Increases, is clamped by the clamp element module, and passes through the first element when the system power switch is turned on. And the fourth pin charge the first capacitor, and when the voltage on the second capacitor is higher than the undervoltage protection voltage threshold of the control device, the control device controls the power of the device by The switch is turned on and off to control the system power switch to be turned on and off, and the first capacitor is controlled to be charged and discharged by controlling the closing and opening of the first switch. The control device according to item 6 of the scope of patent application, wherein the control device controls the on and off of the power switch of the device based on a first control signal, and controls the control device based on a reverse signal of the first control signal. The closing and opening of the first switch are described. The control device according to item 7 of the scope of patent application, wherein the first switch is The first control signal changes from closed to open when the first control signal changes from a low level to a high level, and changes from open to closed after a period of mask time passes when the first control signal changes from a high level to a low level. The control device according to item 6 of the patent application scope, further comprising a second switch connected between the first pin and the fourth pin, and a detection unit for detecting a voltage at the first pin. A test module, and a comparator that generates a second control signal that controls the closing and opening of the second switch based on a comparison result between the voltage detected by the detection module and a predetermined voltage, wherein when the detecting When the voltage detected by the module is higher than the predetermined voltage, the second control signal is at a high level, the second switch is closed, and when the voltage detected by the detection module is lower than the predetermined voltage When the second control signal is at a low level, the second switch is turned off. The control device according to item 9 of the scope of patent application, wherein the predetermined voltage is greater than the voltage at the fourth pin and smaller than the clamp element voltage of the clamp element module. A switching power supply system includes the control device according to any one of claims 1 to 10.