Driving circuit of power switching tube and power conversion circuit using driving circuit

Power transistor drive circuit and power conversion circuit using the same

The present invention relates to the field of electronic technology, and more specifically, to a driving circuit of a power transistor and a power conversion circuit applying the same.

With the rapid development of integrated circuit manufacturing technology, the working frequency is increasing, the accuracy requirements are becoming stricter, and the signal integrity and anti-interference are becoming more and more important. Fluctuations on the power line or the ground line will often have a fatal impact on the system. The reasons for the instability of the power line and the ground line are mainly due to two aspects. One is that the transient alternating current is too large when the device is switched at a high speed; the other is the presence of inductance on the circuit loop. When there is a large current surge in the circuit, it will cause power noise and ground noise (also called ground bounce). For example, when the chip is turned on, a large transient current will flow through the chip and the power plane. The inductance and resistance of the package and the power plane can cause noise, which can cause voltage fluctuations and changes on the power line or ground line. A large amount of current flows into the ground in an instant, and the large current flowing through the impedance of the ground network will pull the ground level higher and deviate from the ground potential. This kind of ground bounce will disturb the output signal and internal logic of the chip, causing the chip to malfunction.

The basic task of the drive circuit is to press the signal from the information electronic circuit According to the requirements of its control target, it is converted into a drive signal that can be added between the control terminal and the common terminal of the power electronic device to turn it on or off, and the drive circuit must provide electrical isolation between the control circuit and the main circuit. The existing output driver structure includes push-pull connected top transistors and bottom transistors, and this structure cannot reduce the voltage fluctuations on the power line or the ground line. 1A, a power transistor driving circuit using the prior art is shown, including a transistor 105, a transistor 110, and a transistor 115 and a resistor 120, wherein the source of the transistor 110 and the power transistor 25 The sources are commonly connected to the ground level. Transistor 105 and transistor 110 respectively receive control signals to generate a corresponding drive signal VG to drive power transistor 25; transistor 115 and resistor 120 are used to optimize the state transition time of power transistor 25 (for example, from off The state changes to the on state). 1B, it shows the working waveform diagram of the driving circuit of the power transistor shown in FIG. The parasitic capacitance of the crystal itself causes the voltage GND and current IGND on the ground level GND2 to fluctuate.

In view of this, the purpose of the present invention is to provide a power transistor drive circuit and a power conversion circuit using the same, so as to overcome the problem of large ground voltage fluctuations in the power transistor drive circuit in the prior art.

In order to achieve the above objective, the present invention provides the following technical solution: a drive circuit for a power transistor according to an embodiment of the present invention, It includes a push-pull drive sub-circuit composed of a top transistor and a bottom transistor, a top transistor drive sub-circuit, and a bottom transistor drive sub-circuit, wherein the first power terminal of the top transistor receives a voltage source; the top transistor The second power terminal of the crystal is connected to the first power terminal of the bottom transistor; the second power terminal of the bottom transistor is connected to a first level; the first level is higher than the ground potential; the top transistor driver The circuit and the bottom transistor drive sub-circuit respectively receive a control signal to drive the top transistor and the bottom transistor accordingly to generate a drive signal at the common connection point of the top transistor and the bottom transistor, To drive the power transistor.

Further, the first power terminal of the power transistor receives an input voltage, and the second power terminal is connected to the ground through a resistive element; the first level is the common of the resistive element and the second power terminal of the power transistor The potential of the connection point.

Preferably, the top transistor is a PMOS transistor, and the bottom transistor is an NMOS transistor.

An integrated driving circuit according to an embodiment of the present invention is used to drive a power stage circuit , the top transistor in the power transistor channel, the push-pull drive circuit comprises integrated drive sub-circuit transistor by the top and bottom of the electric crystals The driving sub-circuit and the bottom transistor driving sub-circuit; wherein, the power stage circuit includes a first ground level; the integrated driving circuit includes a second ground level; the first ground level is connected to the second ground level through a connecting wire Ground level; the first power terminal of the top transistor receives a voltage source; The second power terminal of the top transistor is connected to the first power terminal of the bottom transistor; the second power terminal of the bottom transistor is connected to a first level; the first level is higher than the first ground level The top transistor drive sub-circuit and the bottom transistor drive sub-circuit respectively receive a control signal to drive the top transistor and the bottom transistor accordingly, so that the top transistor and the bottom transistor A driving signal is generated at the common connection point to drive the power transistor.

Further, the first power terminal of the power transistor receives an input voltage, and the second power terminal is connected to the first ground level through a resistive element; the first level is the resistive element and the power transistor The potential at the common connection point of the second power terminal.

Preferably, the top transistor is a PMOS transistor, and the bottom transistor is an NMOS transistor.

A power conversion circuit according to an embodiment of the present invention includes a power stage circuit, a control circuit, and any drive circuit described in items 1-6 in the scope of the patent application. The drive circuit generates a corresponding control signal according to the control signal output by the control circuit. The drive signal to drive the power transistor in the power stage circuit.

Preferably, the power stage circuit has a flyback topology, and the control circuit receives the first level and a feedback signal representing the output voltage of the power stage circuit to generate the control signal.

It can be seen from the above technical solutions that, compared with the prior art, the present invention provides a power transistor drive circuit and a power conversion using the same. It transmits the received control signal through the top power transistor drive circuit and the bottom power transistor drive circuit respectively to control the top power transistor and bottom power transistor connected in series to perform complementary switching actions to output a signal at their common connection point. Drive signal; the second power end of the bottom power transistor in the drive circuit according to the present invention is connected to an independent first level instead of the ground level, thereby avoiding the moment of turning off the power transistor, which is caused by the line Parasitic inductance, parasitic resistance and parasitic capacitance of the power transistor itself cause voltage fluctuations on the ground wire. The driving effect of the driving circuit of the power transistor according to the embodiment of the present invention is better, and the reliability and stability of the system are improved. The driving circuit for power transistors provided by the present invention can drive various types of power transistors, especially MOSFET metal oxide semiconductor transistors.

<p>105Transistor</p><p>110Transistor</p><p>115Transistor</p><p>120Resistor</p><p>25Power Transistor</p><p>201Top transistor drive circuit</p><p>202Bottom transistor drive circuit</p><p>301Control circuit</p><p>302Control circuit and drive circuit</p>

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are merely present. For the embodiments of the invention, for those of ordinary skill in the art, other drawings may be obtained based on the provided drawings without creative work.

FIG. 1A shows a principle block diagram of a driving circuit of a power transistor using the prior art; FIG. 1B shows a working waveform diagram of the driving circuit of a power transistor shown in FIG. 1A; FIG. 2A is a schematic block diagram of a driving circuit of a power transistor according to an embodiment of the present invention; FIG. 2B is a working waveform diagram of the driving circuit of a power transistor according to an embodiment of the present invention shown in FIG. 2A Figure 3 shows a block diagram of a power converter according to an embodiment of the present invention.

Hereinafter, several preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited to these embodiments. The present invention covers any alternatives, modifications, equivalent methods and schemes made on the essence and scope of the present invention. In order for the public to have a thorough understanding of the present invention, specific details are described in the following preferred embodiments of the present invention, and those skilled in the art can fully understand the present invention without the description of these details.

Referring to FIG. 2A, shown is a schematic block diagram of a driving circuit of a power transistor according to an embodiment of the present invention. In this embodiment, the driving circuit of the power transistor includes a top transistor S_W1And bottom transistor S_W2The push-pull drive sub-circuit is composed of a top transistor drive circuit 201 and a bottom transistor drive circuit 202; wherein, the top transistor drive circuit 201 and the bottom transistor drive circuit 202 respectively receive a control signal V_ctrl, To respectively generate corresponding drive signals to the top transistor S_W1And bottom transistor S_W2The control terminal, according to the control signal V_ctrlTo drive the top transistor S_W1And bottom transistor S_W2。

Top transistor S_W1The first power terminal receives the voltage source V_CC, The second power terminal and bottom transistor S_W2The first power terminal is connected, and the voltage at the common connection point of the two is V_GTo drive power transistor Q; bottom transistor S_W2The second power terminal is connected to the first level V_D, The first level V_DThe value of is slightly higher than the ground level; for example, the value can be 500mV. The first power terminal of the power transistor Q receives the input voltage V_in, The second power terminal is coupled to the ground level.

Referring to the working waveform diagram of the driving circuit of the power transistor shown in FIG. 2A shown in FIG. 2B, it can be seen that in the driving circuit of the power transistor according to the embodiment of the present invention, the push-pull driving sub-circuit and the power transistor Q are not shared Ground level. Therefore, there is no need to connect wires between the driving circuit and the second power end of the power transistor. Especially for PCB layout, on the basis of satisfying the normal operation of the driving circuit, the parasitic inductance and parasitic on the connecting wires are eliminated. The ground bounce phenomenon caused by the resistance and the parasitic capacitance of the power transistor itself eliminates the fluctuation of the ground wire level; improves the reliability and stability of the circuit system.

Referring to FIG. 3, shown is a schematic block diagram of a driving circuit of a power transistor according to another embodiment of the present invention. This embodiment describes the implementation of the first level in conjunction with a specific power stage circuit using power transistors.

The power stage circuit is a flyback topology, including the primary winding N_pAnd the secondary winding N_sComposed of transformer T, power transistor Q, output diode D_oAnd output capacitor C_o, To receive the input capacitor C_inFiltered input voltage V_in; The control circuit and the drive circuit 302 output voltage V according to the received characterization_outFeedback signal V_FBAnd detection voltage V_CSTo generate the corresponding control signal V_ctrl; Detection resistance R_CSConnected between the second power terminal of the power transistor Q and the ground level, so that the detection resistance R_CSThe detection voltage V is generated at the common connection point A of the second power terminal of the power transistor Q_CS。

The drive circuit receives the control signal V_ctrlTo drive the top transistor S_W1And bottom transistor S_W2Alternately turn on and off, so that the top transistor S_W1And bottom transistor S_W2The drive signal V is generated at the common connection point B_GTo drive the power transistor Q to generate a substantially constant output voltage V at the output end of the power stage circuit_out。

In this embodiment, the bottom transistor S_W2The second power terminal is connected to the detection resistor R_CSThe common connection point A with the second power terminal of the power transistor Q, the detection voltage V_CSAs the first level.

Wherein, the bottom transistor drive circuit 202 may also include a push-pull drive circuit to drive the bottom transistor S_W2。

The structure of the drive circuit is not limited to the structure described in the above-mentioned embodiments, and can also be other suitable forms of circuit structures, such as those described in Chinese patent applications CN201210142372.9, CN200910078846.6, CN201110039275.2, and US patent applications US12/053,637. The structure of the drive circuit.

The top transistor, the bottom transistor, and the power transistor can be N-type or P-type MOSFET metal oxide semiconductor transistors, bipolar transistors and other types of transistors.

It can be seen that using the power transistor drive circuit shown in FIG. 3 according to the embodiment of the present invention, the push-pull drive sub-circuit and the power transistor Q do not share the ground. Level. For integrated circuits, that is, when the control circuit and the drive circuit 302 are an integrated chip, if the bottom transistor S_W2When the second power terminal of the integrated chip is connected to the common ground GND2 (second ground level) of the integrated chip, during PCB wiring, the common ground GND2 of the integrated chip must be connected to the ground of the power stage circuit (main circuit) through a connecting wire GND1 (first ground level), therefore, the parasitic inductance and parasitic resistance on the connecting wire and the parasitic capacitance of the power transistor itself must be the voltage GND and current I on the ground wire_GNDFluctuations. In the embodiment shown in Figure 3, the bottom transistor S_W2The second power terminal is not connected to the common ground of the integrated chip, but connected to a first level slightly higher than the ground level, that is, the detection resistor R_CSThe common connection point A with the second power terminal of the power transistor Q, thus avoiding the ground current I caused by the connecting wire between the common ground GND2 of the integrated chip and the ground GND1 of the main circuit_GNDAnd the voltage fluctuation on the common ground GND2 of the integrated chip.

The present invention also provides a power conversion circuit, which includes any drive circuit in the above-mentioned embodiments, and further includes a power stage circuit and a control circuit; wherein the control circuit outputs a control signal for controlling the power transistor in the power stage circuit The switching action; the drive circuit receives the control signal, and outputs the drive signal to drive the power transistor to perform the corresponding switching action.

It should be noted that the power transistor drive circuit provided by the present invention can drive various types of power transistors, especially MOSFETs. According to actual needs, it can be connected with different types of power stage circuits and control circuits to form corresponding circuits. The power conversion circuit can be a non-isolated topology structure such as a buck or a boost type, as well as isolation such as a flyback type Type topology.

It should be noted that the functions of the devices with the same name among the various embodiments of the present invention are also the same, and the improved embodiments can be combined with the above-mentioned multiple related embodiments, but the description is only based on the previous embodiment. for example. The top transistor drive circuit and the bottom transistor drive circuit include, but are not limited to, the forms disclosed above, as long as they can realize the functions of the related circuits described in the embodiments of the present invention. Related improvements made on the basis of the disclosed circuit are also within the protection scope of the embodiments of the present invention.

According to the embodiments of the present invention described above, these embodiments do not describe all the details in detail, nor do they limit the present invention to only the specific embodiments described. Obviously, according to the above description, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can make good use of the present invention and make modifications based on the present invention. The present invention is only limited by the scope of the patent application and its full scope and equivalents.