Totem pole PFC circuit and integrated circuit control device and control method thereof

Abstract

The invention discloses a totem pole PFC circuit and an integrated circuit control device and a control method thereof. The totem-pole PFC circuit comprises a high-side switching tube coupled between an output node and a switching node and a low-side switching tube coupled between the switching node and a reference ground, and the integrated circuit control device comprises a first pin coupled to the output node; the second pin is coupled to the control end of the high-side switching tube; the third pin is coupled to the switch node; a switch control circuit generating a high-side control signal based on the AC input voltage; the first comparison circuit is coupled to the first pin and the third pin to receive a first voltage representing the drain-source voltage of the high-side switching tube, and compares the first voltage with a first threshold voltage to generate a high-side turn-off signal; and the first logic circuit is used for generating a high-side driving signal based on the high-side control signal and the high-side turn-off signal so as to control the high-side switch tube. The integrated circuit control device can timely protect the circuit from being damaged by reverse current.

Description

Technical Field

[0001] Embodiments of the present invention relate to electronic circuits, and more specifically, to a totem pole PFC circuit and an integrated circuit control device and a control method thereof. Background Art

[0002] In the field of power supply research and development, in order to improve circuit efficiency, the design of power factor correction (PFC) topology has become increasingly important. Power factor refers to the ratio of effective power to apparent power of a circuit, which is used to measure the degree to which electricity is effectively utilized. The larger the power factor value, the higher the power utilization rate. The technology used to improve the power factor of electrical equipment is called power factor correction. Existing PFC topologies include traditional bridge PFC, semi-bridgeless PFC, and bridgeless PFC. Among bridgeless PFC, totem pole PFC has the advantages of low conduction loss and high circuit efficiency.

[0003] Figure 1 FIG. 1 shows a schematic diagram of the topological structure of an existing totem pole PFC circuit 100. Figure 1 As shown, the totem pole PFC circuit 100 includes: an inductor L1 coupled to an AC input voltage Vac, a first bridge arm including switches S1 and S2, a second bridge arm including switches S3 and S4, and an output capacitor Cout. By controlling the on and off of the switches S1 to S4, the totem pole PFC circuit 100 converts the AC input voltage Vac into an output voltage Vout. Figure 1 As shown, the totem pole PFC circuit 100 further includes diodes Da and Db coupled to the AC input voltage Vac for accelerating the startup process of the totem pole PFC circuit 100 .

[0004] Figure 2 The working state diagram of the switches S1 to S4 of the totem pole PFC circuit 100 is shown. When the AC input voltage Vac is in the positive half cycle, the third switch S3 remains on, the fourth switch S4 remains off, the first switch S1 and the second switch S2 are alternately turned on and off, and the current direction is as follows: Figure 2 (a) and 2(b). When the AC input voltage Vac is in the negative half cycle, the third switch tube S3 remains off, the fourth switch tube S4 remains on, the first switch tube S1 and the second switch tube S2 are alternately turned on and off, and the current direction is as shown in FIG. Figure 2 (c) and 2(d).

[0005] When lightning strikes, inductive voltage surges or other high-voltage spikes occur, the AC input voltage Vac may suddenly reverse, generating a reverse current that damages the system. Take the AC input voltage Vac in the positive half cycle as an example. Figure 3As shown, at this time, the third switch tube S3 remains turned on. If the AC input voltage Vac suddenly changes from positive to negative, the reverse current will flow from node B through the third switch tube S3 and the diode Db into node A, and may also flow through the third switch tube S3, the body diode of the second switch tube S2 and the inductor L1 into node A, thereby damaging the diode Db and the switches S2 and S3. Similarly, when the AC input voltage Vac is in the negative half cycle, if it suddenly changes from negative to positive, the reverse current will also damage the diode Da and the switches S1 and S4. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention proposes a totem pole PFC circuit and an integrated circuit control device and a control method thereof, which can quickly and effectively limit the reverse current, thereby protecting the system from damage.

[0007] According to one embodiment of the present invention, an integrated circuit control device for a totem pole PFC circuit is disclosed. The totem pole PFC circuit includes a high-side switch tube coupled between an output node and a switch node and a low-side switch tube coupled between the switch node and a reference ground. The integrated circuit control device includes: a first pin coupled to the output node; a second pin coupled to the control end of the high-side switch tube; a third pin coupled to the switch node; a switch control circuit that generates a high-side control signal based on an AC input voltage; a first comparison circuit having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is coupled to the first pin, and the second input terminal receives a first threshold voltage. The first comparison circuit compares a first voltage representing a drain-source voltage of the high-side switch tube with the first threshold voltage, and generates a high-side shutdown signal at the output terminal; and a first logic circuit that generates a high-side drive signal based on the high-side control signal and the high-side shutdown signal to control the high-side switch tube.

[0008] According to another embodiment of the present invention, an integrated circuit control device for a totem pole PFC circuit is disclosed, the totem pole PFC circuit includes a high-side switch tube coupled between an output node and a switch node and a low-side switch tube coupled between the switch node and a reference ground, the integrated circuit control device includes: a first pin, coupled to the output node through a first unidirectional device; a second pin, coupled to the control end of the high-side switch tube; a third pin, coupled to the switch node; a first conduction circuit, coupled to the first unidirectional device, providing a conduction path between the first pin and the output node when the AC input voltage is in a negative half cycle; and a first comparison circuit, having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is coupled to the first pin, the second input terminal receives a first threshold voltage, the first comparison circuit compares a first voltage representing a drain-source voltage of the high-side switch tube with the first threshold voltage, and generates a high-side shutdown signal at the output terminal to control the shutdown of the high-side switch tube.

[0009] According to another embodiment of the present invention, a totem pole PFC circuit is disclosed, including: an inductor coupled between a first node and a second node; a first switch tube coupled between an output node and the second node; a second switch tube coupled between the second node and a reference ground; a high-side switch tube coupled between the output node and the switch node; a low-side switch tube coupled between the switch node and the reference ground; and an integrated circuit control device as described above.

[0010] According to another embodiment of the present invention, a control method for a totem pole PFC circuit is disclosed, the totem pole PFC circuit comprising a high-side switch tube coupled between an output node and a switch node and a low-side switch tube coupled between the switch node and a reference ground, the control method comprising: coupling a first pin of an integrated circuit control device to the output node through a first unidirectional device; coupling a second pin of the integrated circuit control device to a control end of the high-side switch tube; coupling a third pin of the integrated circuit control device to the switch node; generating a high-side control signal based on an AC input voltage; when the AC input voltage is in a negative half cycle, turning on the first unidirectional device to provide a first conduction path between the first pin and the output node; coupling to the first pin and the third pin to receive a first voltage representing a drain-source voltage of the high-side switch tube through the first conduction path; comparing the first voltage with a first threshold voltage to generate a high-side shutdown signal; and generating a high-side drive signal based on the high-side control signal and the high-side shutdown signal to control the high-side switch tube.

[0011] According to an embodiment of the present invention, by comparing the drain-source voltage of the high-side switch tube with the first threshold voltage in the negative half cycle of the AC input voltage, and comparing the drain-source voltage of the low-side switch tube with the second threshold voltage in the positive half cycle of the AC input voltage, the reverse current can be detected quickly and effectively, thereby cutting off the reverse current loop and protecting the system from damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to better understand the present invention, the present invention will be described in detail according to the following drawings:

[0013] Figure 1 A schematic diagram of the topological structure of an existing totem pole PFC circuit 100 is shown;

[0014] Figure 2 The working state diagram of the switch tubes S1 to S4 of the totem pole PFC circuit 100 is shown;

[0015] Figure 3 shows the current flow diagram when the AC input voltage Vac changes from positive to negative;

[0016] Figure 4 1 shows a circuit block diagram of a totem pole PFC circuit 200 according to an embodiment of the present invention;

[0017] Figure 5 The present invention shows an embodiment of Figure 4 The operating waveform diagram 500 of the totem pole PFC circuit 200 is shown;

[0018] Figure 6 Another embodiment of the present invention is shown. Figure 4 The operating waveform diagram 600 of the totem pole PFC circuit 200 is shown;

[0019] Figure 7 1 shows a circuit block diagram of a totem pole PFC circuit 200A according to an embodiment of the present invention;

[0020] Figure 8 FIG. 4 is a schematic diagram showing a circuit structure of a totem pole PFC circuit 200B according to an embodiment of the present invention;

[0021] Fig. 9 FIG. 4 shows a circuit structure diagram of a totem pole PFC circuit 200C according to an embodiment of the present invention;

[0022] Fig.10 FIG. 4 is a schematic diagram showing a circuit structure of a totem pole PFC circuit 200D according to an embodiment of the present invention;

[0023] Fig.11 A schematic diagram of the circuit structure of a totem pole PFC circuit 200E according to an embodiment of the present invention is shown;

[0024] Fig.12 A circuit structure diagram of a totem pole PFC circuit 200F according to an embodiment of the present invention is shown;

[0025] Fig.13 A circuit structure diagram of a totem pole PFC circuit 200G according to an embodiment of the present invention is shown;

[0026] Fig.14 A circuit structure diagram of a totem pole PFC circuit 200H according to an embodiment of the present invention is shown;

[0027] Fig.15 A flow chart of a control method 1500 for a totem pole PFC circuit according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0028] The specific embodiments of the present invention will be described in detail below. It should be noted that the embodiments described herein are only for illustration and are not intended to limit the present invention. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that these specific details do not have to be used to implement the present invention. In other examples, in order to avoid confusing the present invention, known circuits, materials or methods are not specifically described.

[0029] Throughout the specification, references to "one embodiment", "an embodiment", "an example" or "an example" mean that a particular feature, structure or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "in one embodiment", "in an embodiment", "an example" or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. In addition, particular features, structures or characteristics may be combined in one or more embodiments or examples in any appropriate combination and / or sub-combination. In addition, it should be understood by those of ordinary skill in the art that the drawings provided herein are for illustrative purposes and that the drawings are not necessarily drawn to scale. The same reference numerals indicate the same device. It should be understood that when an "element" is said to be "connected to" or "coupled" to another element, it may be directly connected or coupled to another element or there may be an intermediate element. In contrast, when an element is said to be "directly connected to" or "directly coupled to" another element, there is no intermediate element. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0030] Throughout the specification, relative terms such as first and second, etc. may be used only to distinguish one entity or action from another entity or action, and do not necessarily or imply the existence of such an order between these entities or actions. Numerical sequences such as "first", "second", "third", etc. refer only to different individuals in a plurality and do not imply any order or sequence unless specifically defined in the claim language. The order of the text in any claim does not mean that the processing steps must be performed in such order or logical order unless specifically specified in the claim language. Without departing from the scope of the present invention, these processing steps can be interchanged in any order, as long as such interchange does not cause the claim language to contradict and does not appear logically absurd.

[0031] Figure 4 FIG. 4 shows a circuit block diagram of a totem pole PFC circuit 200 according to an embodiment of the present invention. Figure 4As shown, the totem pole PFC circuit 200 includes a switch circuit 10 and an integrated circuit control device 20. The switch circuit 10 includes: an inductor L1, coupled between a first node T1 and a second node T2; a switch tube S1, coupled between an output node T3 and a second node T2; a switch tube S2, coupled between the second node T2 and a reference ground GND1; a switch tube S3, coupled between a switch node SW and a reference ground GND1; a switch tube S4, coupled between an output node T3 and a switch node SW; and an output capacitor Cout, coupled between the output node T3 and the reference ground GND1. The switch circuit 10 converts an AC input voltage Vac into an output voltage Vout by turning on and off the switches S1 to S4. The totem pole PFC circuit 200 also includes a diode Da coupled between the output node T3 and the first node T1 and a diode Db coupled between the first node T1 and the reference ground GND1, which are used to accelerate the startup process of the totem pole PFC circuit 200. Those skilled in the art will appreciate that the switch tubes S1 - S4 may be any controllable semiconductor devices, such as BJT, JFET, MOSFET, IGBT or GaNFET.

[0032] The integrated circuit control device 20 has multiple pins, including a pin GHQ coupled to the control end of the switch tube S1, a pin GLQ coupled to the control end of the switch tube S2, a pin RCH coupled to the output node T3, a pin GHS coupled to the control end of the switch tube S4, a pin SWN coupled to the switch node SW, a pin GLS coupled to the control end of the switch tube S3, and a pin GND coupled to the reference ground GND1.

[0033] exist Figure 4 In the illustrated embodiment, the integrated circuit control device 20 includes a first comparison circuit 201 , a first logic circuit 202 , a second comparison circuit 203 , a second logic circuit 204 , and a switch control circuit 205 .

[0034] The first comparison circuit 201 is coupled to the pin RCH and the pin SWN to receive the first voltage Vds1 representing the drain-source voltage of the switch tube S4, and compares the first voltage Vds1 with the first threshold voltage Vth1 to generate a high-side shutdown signal HOS. In one embodiment, when the first voltage Vds1 is greater than the first threshold voltage Vth1, the high-side shutdown signal HOS is valid (such as a high level). In one embodiment, the first comparison circuit 201 has a first input terminal, a second input terminal, a reference ground terminal and an output terminal, wherein the first input terminal is coupled to the pin RCH, the second input terminal receives the first threshold voltage Vth1, the reference ground terminal is coupled to the pin SWN, and the output terminal provides the high-side shutdown signal HOS.

[0035] The switch control circuit 205 generates a high-side control signal HCS and a low-side control signal LCS based on the AC input voltage Vac. In one embodiment, when the AC input voltage Vac is in the positive half cycle, the high-side control signal HCS is invalid (such as a low level), and the low-side control signal LCS is valid (such as a high level); when the AC input voltage Vac is in the negative half cycle, the high-side control signal HCS is valid (such as a high level), and the low-side control signal LCS is invalid (such as a low level). In one embodiment, when the AC input voltage Vac is greater than the positive voltage threshold Vzero, it is considered that the AC input voltage Vac is in the positive half cycle; when the AC input voltage Vac is less than the negative voltage threshold -Vzero, it is considered that the AC input voltage Vac is in the negative half cycle. In one embodiment, the positive voltage threshold Vzero can be a value slightly greater than 0, and similarly, the negative voltage threshold -Vzero can be a value slightly less than 0. Figure 2 In the illustrated embodiment, the switch control circuit 205 further generates switch control signals HCQ and LCQ to control the on and off of the switch tubes S1 and S2 respectively.

[0036] The first logic circuit 202 receives the high-side shutdown signal HOS and the high-side control signal HCS, and generates a high-side drive signal HDS based on the high-side shutdown signal HOS and the high-side control signal HCS to control the on and off of the switch tube S4. In one embodiment, when the high-side shutdown signal HOS is valid or the high-side control signal HCS is invalid, the switch tube S4 is turned off.

[0037] The second comparison circuit 203 is coupled to the pin SWN and the pin GND to receive the second voltage Vds2 representing the drain-source voltage of the switch tube S3, and compares the second voltage Vds2 with the second threshold voltage Vth2 to generate a low-side shutdown signal LOS. In one embodiment, when the second voltage Vds2 is greater than the second threshold voltage Vth2, the low-side shutdown signal LOS is effective (such as a high level). In one embodiment, the first threshold voltage Vth1 has the same value as the second threshold voltage Vth2. In one embodiment, the second comparison circuit 203 has a first input terminal, a second input terminal, a reference ground terminal and an output terminal, wherein the first input terminal is coupled to the pin SWN, the second input terminal receives the second threshold voltage Vth2, the reference ground terminal is coupled to the pin GND, and the output terminal provides a low-side shutdown signal LOS.

[0038] The second logic circuit 204 receives the low-side shutdown signal LOS and the low-side control signal LCS, and generates a low-side drive signal LDS based on the low-side shutdown signal LOS and the low-side control signal LCS to control the on and off of the switch tube S3. In one embodiment, when the low-side shutdown signal LOS is valid or the low-side control signal LCS is invalid, the switch tube S3 is turned off.

[0039] In one embodiment, the integrated circuit control device 20 further includes a driving circuit for driving the switching transistors S1 to S4 to be turned on and off based on the switch control signals HCQ and LCQ, the high-side driving signal HDS and the low-side driving signal LDS.

[0040] Figure 5 The present invention shows an embodiment of Figure 4 The working waveform diagram 500 of the totem pole PFC circuit 200 is shown. Figure 4 and Figure 5 The working principle of the totem pole PFC circuit 200 is described below.

[0041] When the AC input voltage Vac is in the negative half cycle, the high-side control signal HCS is at a high level. In the time period t1-t2, the AC input voltage Vac suddenly changes from negative to positive, generating a reverse current flowing from the drain to the source of the switch tube S4, causing the first voltage Vds1 to increase to the first threshold voltage Vth1, so the high-side shutdown signal HOS switches from a low level to a high level. The high-side drive signal HDS then switches from a high level to a low level, turning off the switch tube S4. After that, the switch tube S4 remains off until the next negative half cycle of the AC input voltage Vac arrives at time t3, that is, the rising edge of the high-side control signal HCS arrives, and the high-side drive signal HDS switches from a low level to a high level, turning on the switch tube S4.

[0042] Similarly, when the AC input voltage Vac is in the positive half cycle, the low-side control signal LCS is at a high level. In the time period t4-t5, the AC input voltage Vac suddenly changes from positive to negative, generating a reverse current flowing from the drain of the switch tube S3 to the source, causing the second voltage Vds2 to increase to the second threshold voltage Vth2, and therefore, the low-side shutdown signal LOS switches from a low level to a high level. The low-side drive signal LDS then switches from a high level to a low level, turning off the switch tube S3. Afterwards, the switch tube S3 remains off until the next positive half cycle of the AC input voltage Vac arrives at t6, that is, the rising edge of the low-side control signal LCS arrives, and the low-side drive signal LDS switches from a low level to a high level, turning on the switch tube S3.

[0043] Figure 6 Another embodiment of the present invention is shown. Figure 4 The operating waveform diagram 600 of the totem pole PFC circuit 200 is shown. Figure 5The difference is that at time t2, the AC input voltage Vac returns to normal, the first voltage Vds1 decreases to the first threshold voltage Vth1, and the high-side drive signal HDS immediately switches from a low level to a high level, turning on the switch tube S4. Similarly, at time t5, the AC input voltage Vac returns to normal, the second voltage Vds2 decreases to the second threshold voltage Vth2, and the low-side drive signal LDS immediately switches from a low level to a high level, turning on the switch tube S3.

[0044] Those skilled in the art can understand that the switch tubes S3 and S4 can be turned on at any appropriate time after the AC input voltage Vac returns to normal. For example, the switch tube S4 can be turned on at any time in the time period t2 to ta, and the switch tube S3 can be turned on at any time in the time period t5 to tb.

[0045] According to an embodiment of the present invention, when it is detected that the first voltage Vds1 is greater than the first threshold voltage Vth1 or the second voltage Vds2 is greater than the second threshold voltage Vth2, the switch tube S4 or the switch tube S3 is immediately turned off to cut off the current loop of the reverse current, which can quickly and effectively limit the reverse current and protect the switch tube and diode from being damaged by the reverse current.

[0046] Figure 7 FIG. 2 shows a circuit block diagram of a totem pole PFC circuit 200A according to an embodiment of the present invention. Figure 4 The difference is that the integrated circuit control device 20A further includes a first filter circuit 207 and a second filter circuit 208. Figure 7 In the illustrated embodiment, the first comparison circuit 201 generates a first comparison signal CA1 based on a comparison result between the first voltage Vds1 and the first threshold voltage Vth1. The first filter circuit 207 is coupled to the first comparison circuit 201 to receive the first comparison signal CA1, and after filtering the first comparison signal CA1, provides a high-side shutdown signal HOS to reduce the influence of noise on the comparison result.

[0047] Similarly, the second comparison circuit 202 generates a second comparison signal CA2 based on the comparison result of the second voltage Vds2 and the second threshold voltage Vth2. The second filter circuit 208 is coupled to the second comparison circuit 202 to receive the second comparison signal CA2, and after filtering the second comparison signal CA2, provides a low-side shutdown signal LOS. For the sake of clarity, other circuit structures of the switch circuit 10 and the integrated circuit control device 20A are not shown in the figure. Figure 7 Shown in.

[0048] Figure 8 FIG. 2 shows a schematic diagram of a circuit structure of a totem pole PFC circuit 200B according to an embodiment of the present invention. Figure 8As shown, the first comparison circuit 201B includes a comparator CMP1. The comparator CMP1 has a non-inverting input terminal, an inverting input terminal, a reference ground terminal and an output terminal, wherein the non-inverting input terminal is coupled to the pin RCH, the inverting input terminal receives the first threshold voltage Vth1, and the reference ground terminal is coupled to the pin SWN. The comparator CMP1 compares the first voltage Vds1 with the first threshold voltage Vth1 and generates a first comparison signal CA1 at the output terminal. When the first voltage Vds1 is greater than the first threshold voltage Vth1, the first comparison signal CA1 is at a high level.

[0049] The first filter circuit 207B includes a first timer, which counts the duration of the first comparison signal CA1 being at a high level, and generates a high-side shutdown signal HOS. When the timing duration is greater than the first time threshold tth1, the high-side shutdown signal HOS is switched from an invalid state to a valid state, for example, from a low level to a high level. It can be understood by those skilled in the art that due to the influence of noise, the first comparison signal CA1 may jitter and jump between different levels, so the first timer can accumulate the duration of the first comparison signal CA1 being at a high level within a negative half cycle of the AC input voltage Vac, and the above-mentioned timing duration is the accumulated duration of the first comparison signal CA1 being at a high level.

[0050] The first logic circuit 202B includes a NOT gate NOT1, an OR gate OR1 and a trigger FF1. The NOT gate NOT1 performs a logical NOT operation on the high-side control signal HCS to generate a high-side NOT signal HNS. The OR gate OR1 performs a logical OR operation on the high-side shutdown signal HOS and the high-side NOT signal HNS to generate a high-side OR signal CHR. The set terminal S of the trigger FF1 receives the high-side control signal HCS, and the reset terminal R receives the high-side OR signal CHR. Based on the high-side control signal HCS and the high-side OR signal CHR, the trigger FF1 provides a high-side drive signal HDS at the output terminal Q. When the rising edge of the high-side control signal HCS comes, the high-side drive signal HDS is at a high level; when the high-side OR signal CHR is at a high level, the high-side drive signal HDS is at a low level.

[0051] The second comparison circuit 203B includes a comparator CMP2. The comparator CMP2 has a non-inverting input terminal, an inverting input terminal, a reference ground terminal and an output terminal, wherein the non-inverting input terminal is coupled to the pin SWN, the inverting input terminal receives the second threshold voltage Vth2, and the reference ground terminal is coupled to the pin GND. The comparator CMP2 compares the second voltage Vds2 with the second threshold voltage Vth2 and generates a second comparison signal CA2 at the output terminal. When the second voltage Vds2 is greater than the second threshold voltage Vth2, the second comparison signal CA2 is high level.

[0052] The second filtering circuit 208B includes a second timer, and the duration of the second comparison signal CA2 being a high level is timed to generate a low-side shut-off signal LOS. Wherein when the timing duration is greater than the second time threshold tth2, the low-side shut-off signal LOS is effective, such as switching from a low level to a high level. It will be appreciated by those skilled in the art that due to the influence of noise, the second comparison signal CA2 may jitter, jump between different levels, and the timing duration of the second timer can be the cumulative duration of the second comparison signal CA2 being a high level. In one embodiment, the first time threshold tth1 and the second time threshold tth2 have the same value, for example, 200 nanoseconds.

[0053] The second logic circuit 204B includes a NOT gate NOT2, an OR gate OR2 and a trigger FF2. NOT gate NOT2 performs a logical NOT operation on the low-side control signal LCS to generate a low-side non-signal LNS. OR gate OR2 performs a logical OR operation on the low-side shutdown signal LOS and the low-side non-signal LNS to generate a low-side OR signal CLR. The set end S of the trigger FF2 receives the low-side control signal LCS, and the reset end R receives the low-side OR signal CLR. Based on the low-side control signal LCS and the low-side OR signal CLR, the trigger FF2 provides a low-side drive signal LDS at the output end Q. When the rising edge of the low-side control signal LCS comes, the low-side drive signal LDS is at a high level; when the low-side OR signal CLR is at a high level, the low-side drive signal LDS is at a low level.

[0054] Fig. 9 FIG. 2 shows a schematic diagram of a circuit structure of a totem pole PFC circuit 200C according to an embodiment of the present invention. Figure 8 The difference is that the first filter circuit 207C includes a resistor R1 and a capacitor C1, and the connection relationship is as follows: Fig. 9 As shown. The resistor R1 and the capacitor C1 form a low-pass filter to filter out the burrs in the first comparison signal CA1. When the filtered first comparison signal CA1 is at a high level, the high-side shutdown signal HOS is valid.

[0055] Similarly, the second filter circuit 208C includes a resistor R2 and a capacitor C2. The low-pass filter formed by the resistor R2 and the capacitor C2 is used to filter out the burrs in the second comparison signal CA2. When the filtered second comparison signal CA2 is at a high level, the low-side shutdown signal LOS is valid.

[0056] Fig.10 FIG. 2 shows a schematic diagram of a circuit structure of a totem pole PFC circuit 200D according to an embodiment of the present invention. Figure 8The difference is that the first logic circuit 202D includes a NOT gate NOT3 and an AND gate AND1. The NOT gate NOT3 performs a logic NOT operation on the high-side shutdown signal HOS to generate a high-side non-shutdown signal NHOF. The AND gate AND1 performs a logic AND operation on the high-side non-shutdown signal NHOF and the high-side control signal HCS to generate a high-side drive signal HDS.

[0057] The second logic circuit 204D includes a NOT gate NOT4 and an AND gate AND2. The NOT gate NOT4 performs a logical NOT operation on the low-side shutdown signal LOS to generate a low-side non-shutdown signal NLOF. The AND gate AND2 performs a logical AND operation on the low-side non-shutdown signal NLOF and the low-side control signal LCS to generate a low-side drive signal LDS.

[0058] Fig.11 FIG. 2 shows a schematic diagram of a circuit structure of a totem pole PFC circuit 200E according to an embodiment of the present invention. Fig.11 As shown, the totem pole PFC circuit 200E further includes a first unidirectional conducting device, a first conducting circuit 209, a second unidirectional device, and a second conducting circuit 210. Fig.11 In the illustrated embodiment, the first unidirectional device includes a first diode D1 and the second unidirectional device includes a second diode D2.

[0059] exist Fig.11 In the embodiment shown, the first diode D1 is coupled between the pin RCH and the first end of the switch tube S4 (ie, the output node T3 ), wherein the first diode D1 has an anode and a cathode, wherein the anode is coupled to the pin RCH and the cathode is coupled to the first end of the switch tube S4 .

[0060] The first conduction circuit 209 is coupled to the first diode D1. When the AC input voltage Vac is in the negative half cycle, the first conduction circuit 209 conducts the first diode D1, providing a conduction path between the pin RCH and the first end of the switch tube S4 (i.e., a conduction path from the pin RCH to the output node T3), so that the first comparison circuit 201E can correctly receive the first voltage Vds1 representing the drain-source voltage of the switch tube S4. In one embodiment, when the AC input voltage Vac is in the positive half cycle, the first diode D1 is turned off, disconnecting the path between the pin RCH and the first end of the switch tube S4.

[0061] The second diode D2 is coupled between the first input terminal of the second comparison circuit 203E and the pin SWN. The second diode D2 has an anode and a cathode, the anode is coupled to the input terminal of the second comparison circuit 203E, and the cathode is coupled to the pin SWN.

[0062] The second conduction circuit 210 is coupled to the second diode D2. When the AC input voltage Vac is in the positive half cycle, the second conduction circuit 210 turns on the second diode D2, providing a conduction path between the first input terminal of the second comparison circuit 203E and the pin SWN, so that the comparison circuit 203E can correctly receive the second voltage Vds2 representing the drain-source voltage of the switch tube S3. In one embodiment, when the AC input voltage Vac is in the negative half cycle, the second diode D2 is turned off, disconnecting the path between the first input terminal of the second comparison circuit 203E and the pin SWN.

[0063] In other embodiments, the second unidirectional device may also be placed outside the integrated circuit control device. Fig.12 As shown, the integrated circuit control device 20F further includes a pin RCL, and the pin RCL is coupled to the switch node SW through a third unidirectional device. Fig.12 In the illustrated embodiment, the third unidirectional device includes a third diode D3, wherein the anode of the third diode D3 is coupled to the pin RCL, and the cathode is coupled to the switch node SW. When the AC input voltage Vac is in a positive half cycle, the third conduction circuit 220 turns on the third diode D3, thereby providing a conduction path from the pin RCL to the switch node SW. When the AC input voltage Vac is in a negative half cycle, the third diode D3 is turned off, disconnecting the path between the pin RCL and the switch node SW.

[0064] In one embodiment, the first diode D1, the second diode D2 and the third diode D3 are high voltage resistant diodes, which are used to limit the voltage on the pin RCH and / or the pin RCL to prevent the circuits and components inside the integrated circuit control device 20 from being damaged by the high voltage.

[0065] In one embodiment, the first conduction circuit 209 is enabled only when the AC input voltage Vac is in a negative half cycle, and the second conduction circuit 210 and the third conduction circuit 220 are enabled only when the AC input voltage Vac is in a positive half cycle to reduce power loss.

[0066] The first conducting circuit 209, the second conducting circuit 210 and the third conducting circuit 220 have various suitable circuit structures. Fig.13 In the illustrated embodiment, the first conduction circuit 209G includes a current source IS1 coupled to the first power supply voltage VCCH, and the second conduction circuit 210G includes a current source IS2 coupled to the second power supply voltage VCCL. In one embodiment, the current source IS1 is turned on only when the AC input voltage Vac is in the negative half cycle, and the current source IS2 is turned on only when the AC input voltage Vac is in the positive half cycle. Fig.14In the illustrated embodiment, the first conduction circuit 209H includes a resistor R3 coupled to the first supply voltage VCCH, and the second conduction circuit 210H includes a resistor R4 coupled to the second supply voltage VCCL.

[0067] Fig.15 FIG. 1 is a flow chart of a control method 1500 for a totem pole PFC circuit according to an embodiment of the present invention. The totem pole PFC circuit includes switch tubes S1 to S4, and the connection relationship thereof is as follows: Figure 4 As shown, by controlling the on and off of the switches S1 to S4, the totem pole PFC circuit converts the AC input voltage Vac into the output voltage Vout. The control method 1500 includes steps S101 to S108.

[0068] In step S101, it is detected and determined whether the AC input voltage Vac is in the positive half cycle or the negative half cycle. If it is in the negative half cycle, the process proceeds to step S102; if it is in the positive half cycle, the process proceeds to step S105; if it is neither in the positive half cycle nor in the negative half cycle, the process proceeds to step S108. In one embodiment, when the AC input voltage Vac is greater than the positive voltage threshold Vzero, the AC input voltage Vac is considered to be in the positive half cycle; when the AC input voltage Vac is less than the negative voltage threshold -Vzero, the AC input voltage Vac is considered to be in the negative half cycle. In one embodiment, the positive voltage threshold Vzero may be a value slightly greater than 0, and similarly, the negative voltage threshold -Vzero may be a value slightly less than 0.

[0069] In step S102, the switch tube S3 is turned off and the switch tube S4 is turned on.

[0070] In step S103, the first voltage Vds1 representing the drain-source voltage of the switch tube S4 is monitored and compared with the first threshold voltage Vth1. If the drain-source voltage Vds1 is greater than the first threshold voltage Vth1, step S104 is entered; otherwise, step S103 is repeated.

[0071] In step S104, the switch tube S4 is turned off.

[0072] In step S105, the switch tube S3 is turned on and the switch tube S4 is turned off.

[0073] In step S106, the second voltage Vds2 representing the drain-source voltage of the switch tube S3 is monitored and compared with the second threshold voltage Vth2. If the drain-source voltage Vds2 is greater than the second threshold voltage Vth2, step S107 is entered; otherwise, step S106 is repeated.

[0074] In step S107, the switch tube S3 is turned off.

[0075] In step S108, both switch tubes S3 and S4 are turned off.

[0076] Note that in the flowcharts described above, the functions marked in the boxes can also be different from Fig.15 For example, two blocks shown in succession may actually be executed substantially in parallel, or they may sometimes be executed in the reverse order, depending on the specific functionality involved.

[0077] It should be understood that the relationship between the logic level of the above-mentioned control signal and the on-off of the switch tube is related to the type of switch tube used. For example, if the switch tube is an N-type MOSFET, when the control signal is a logic high level, the corresponding switch tube is turned on, and when the control signal is a logic low level, the corresponding switch tube is turned off. If the switch tube is a P-type MOSFET, when the control signal is a logic high level, the corresponding switch tube is turned off, and when the control signal is a logic low level, the corresponding switch tube is turned on. The level type of the control signal and the on-off relationship of the switch tube in the embodiment of the present invention are only used for illustration, and are not used to limit the type of control signal in the present invention and the relationship between the type of control signal and the on-off of the switch tube.

[0078] Those skilled in the art will appreciate that the circuits provided in the above embodiments are only for illustrative purposes. Any circuit that can implement the functions and working processes of the circuits in the embodiments of the present invention does not deviate from the spirit or essence of the present invention. For example, in some embodiments, the circuits in the embodiments of the present invention can be specifically described using digital description languages ​​such as VHDB and Verilog, thereby automatically generating digital circuits to implement the corresponding functions.

[0079] Although the present invention has been described with reference to several typical embodiments, it should be understood that the terms used are illustrative and exemplary, rather than restrictive. Since the present invention can be embodied in a variety of forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. An integrated circuit control device for a totem pole PFC circuit, the totem pole PFC circuit comprising a high-side switch tube coupled between an output node and a switch node and a low-side switch tube coupled between the switch node and a reference ground, the integrated circuit control device comprising: A first pin coupled to an output node; A second pin is coupled to the control end of the high-side switch tube; A third pin coupled to the switch node; A switch control circuit generates a high-side control signal based on an AC input voltage; A first comparison circuit has a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is coupled to the first pin, the second input terminal receives a first threshold voltage, the first comparison circuit compares a first voltage representing a drain-source voltage of the high-side switch tube with the first threshold voltage, and generates a high-side shutdown signal at the output terminal; as well as The first logic circuit generates a high-side driving signal based on the high-side control signal and the high-side shutdown signal to control the high-side switch tube. 2 . The integrated circuit control device as claimed in claim 1 , wherein when the first voltage is greater than a first threshold voltage, the high-side switch tube is turned off. 3 . The integrated circuit control device as claimed in claim 1 , wherein when the rising edge of the high-side control signal comes, the high-side switch tube is turned on.

4. The integrated circuit control device of claim 1, wherein the first pin is coupled to the output node through a first unidirectional device, the integrated circuit control device further comprising: The first conduction circuit is coupled to the first unidirectional device and provides a conduction path between the first pin and the output node when the AC input voltage is in a negative half cycle. 5 . The integrated circuit control device as claimed in claim 4 , wherein the first conduction circuit comprises a first current source or a first resistor coupled between the first power supply voltage and the first pin.

6. The integrated circuit control device of claim 1, further comprising: The first filtering circuit is coupled to the first comparing circuit, and provides the high-side shutdown signal after filtering the comparison result between the first voltage and the first threshold voltage.

7. The integrated circuit control device of claim 1, wherein the switch control circuit further generates a low-side control signal based on an AC input voltage, and the integrated circuit control device further comprises: A fourth pin is coupled to the control end of the low-side switch tube; A fifth pin coupled to a reference ground; A second comparison circuit has a first input terminal, a second input terminal and an output terminal, wherein the second input terminal receives a second threshold voltage, the second comparison circuit compares a second voltage representing a drain-source voltage of the low-side switch tube with the second threshold voltage, and generates a low-side shutdown signal at the output terminal; as well as The second logic circuit generates a low-side driving signal based on the low-side control signal and the low-side shutdown signal to control the low-side switch tube.

8. The integrated circuit control device of claim 7, further comprising: A second unidirectional device coupled between the first input terminal of the second comparison circuit and the third pin; as well as The second conduction circuit is coupled to the second unidirectional device, and provides a conduction path between the first input terminal of the second comparison circuit and the third pin when the AC input voltage is in a positive half cycle.

9. The integrated circuit control device of claim 7, further comprising: A sixth pin coupled to the switch node via a third unidirectional device, wherein the first input terminal of the second comparison circuit is coupled to the sixth pin; as well as The third conduction circuit is coupled to the third unidirectional device, and provides a conduction path between the sixth pin and the switch node when the AC input voltage is in a positive half cycle.

10. An integrated circuit control device for a totem pole PFC circuit, the totem pole PFC circuit comprising a high-side switch tube coupled between an output node and a switch node and a low-side switch tube coupled between the switch node and a reference ground, the integrated circuit control device comprising: A first pin coupled to an output node through a first unidirectional device; A second pin is coupled to the control end of the high-side switch tube; A third pin coupled to the switch node; A first conduction circuit, coupled to the first unidirectional device, provides a conduction path between the first pin and the output node when the AC input voltage is in a negative half cycle; as well as The first comparison circuit has a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is coupled to the first pin, the second input terminal receives a first threshold voltage, the first comparison circuit compares a first voltage representing a drain-source voltage of a high-side switch tube with the first threshold voltage, and generates a high-side shutdown signal at the output terminal to control the shutdown of the high-side switch tube.

11. The integrated circuit control device of claim 10, further comprising: A fourth pin is coupled to the control end of the low-side switch tube; A fifth pin coupled to a reference ground; as well as The second comparison circuit has a first input terminal, a second input terminal and an output terminal, wherein the second input terminal receives a second threshold voltage. The second comparison circuit compares a second voltage representing the drain-source voltage of the low-side switch tube with the second threshold voltage, and generates a low-side shutdown signal at the output terminal to control the shutdown of the low-side switch tube.

12. The integrated circuit control device of claim 11, further comprising: A second unidirectional device coupled between the first input terminal of the second comparison circuit and the third pin; as well as The second conduction circuit is coupled to the second unidirectional device, and provides a conduction path between the first input terminal of the second comparison circuit and the third pin when the AC input voltage is in a positive half cycle.

13. The integrated circuit control device of claim 11, further comprising: A sixth pin coupled to the switch node via a third unidirectional device, wherein the first input terminal of the second comparison circuit is coupled to the sixth pin; as well as The third conduction circuit is coupled to the third unidirectional device, and provides a conduction path between the sixth pin and the switch node when the AC input voltage is in a positive half cycle.

14. A totem pole PFC circuit, comprising: an inductor coupled between the first node and the second node; A first switch tube is coupled between the output node and the second node; A second switch tube is coupled between the second node and the reference ground; A high-side switch tube coupled between the output node and the switch node; A low-side switch tube is coupled between the switch node and a reference ground; as well as An integrated circuit control device as claimed in any one of claims 1 to 13.

15. The totem pole PFC circuit of claim 14, further comprising: A first diode coupled between the output node and the first node; as well as The second diode is coupled between the first node and the reference ground.

16. A control method for a totem pole PFC circuit, the totem pole PFC circuit comprising a high-side switch tube coupled between an output node and a switch node and a low-side switch tube coupled between the switch node and a reference ground, the control method comprising: coupling a first pin of the integrated circuit control device to an output node via a first unidirectional device; Coupling the second pin of the integrated circuit control device to the control end of the high-side switch tube; coupling a third pin of the integrated circuit control device to the switch node; generating a high-side control signal based on an AC input voltage; When the AC input voltage is in a negative half cycle, turning on the first unidirectional device to provide a first conduction path between the first pin and the output node; coupled to the first pin and the third pin to receive a first voltage representing a drain-source voltage of the high-side switch tube through a first conduction path; comparing the first voltage with a first threshold voltage to generate a high-side shutdown signal; as well as A high-side driving signal is generated based on the high-side control signal and the high-side shutdown signal to control the high-side switch tube.

17. The control method according to claim 16, further comprising: Coupling the fourth pin of the integrated circuit control device to the control end of the low-side switch tube; generating a low-side control signal based on an AC input voltage; When the AC input voltage is in a positive half cycle, a second voltage representing the drain-source voltage of the low-side switch tube is compared with a second threshold voltage to generate a low-side shutdown signal; as well as A low-side driving signal is generated based on the low-side control signal and the low-side shutdown signal to control the low-side switch tube.

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