JP2009141783A - Drive control circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a malfunction of a drive control circuit that supplies a driving signal to a semiconductor element. <P>SOLUTION: When the driving signal is applied to a gate of a main circuit element 17, the circuit element 17 is switched on and a current corresponding to a switch-on period of the driving signal flows. At this moment, a potential difference is caused by the inductance of a wiring cable CABLE 2 between ground points (a) and (b). However, a ground loop is not formed since the ground wiring G1 (grounding wire) of an internal power source circuit 13 in the drive control circuit 11 and the ground wiring G2 of a driving circuit 14 are separated by a current restriction resistance R1 inserted in a power source line P1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a drive control circuit for supplying a drive signal to a semiconductor element.

A drive control circuit is used for on / off control of a main circuit element (such as a transistor) that controls a current supplied to a load.
FIG. 2 is a diagram showing a conventional drive control circuit 21 and main circuit elements that control the current supplied to the load 26.

  The drive control circuit 21 is mounted on a control board 22 and includes an in-board power supply circuit 23 including a smoothing capacitor C21 and a drive circuit 23 including a capacitor C22. The drive signal generated by the drive circuit 24 is output to the control terminal (gate) of the main circuit element 27 such as a MOS transistor or a bipolar transistor. The main circuit element 27 is a switching element that controls a current supplied from the external power supply 25 to the load 26.

  The ground (ground) of the internal power supply circuit 23 of the control board 22 and the ground of the drive circuit 24 are connected by a ground line G21. One end of the load 26 is connected to the positive electrode side of the external power supply 25 by the wiring cable CABLE1, and the source of the main circuit element 27 connected in series with the load 26 is connected to the ground of the drive circuit 24 and wiring The cable CABLE2 is connected to the ground of the external power supply 25.

  In the circuit of FIG. 2, when the main circuit element 27 is switched, a potential difference is generated between the ground point a of the main circuit element 27 and the ground point b of the external power supply 25 due to the inductance component and resistance component of the wiring cable CABLE2. .

  In the circuit of FIG. 2, since the ground wiring G21 on the control board 21 and the wiring cable CABLE2 connecting the grounding point of the main circuit element 24 and the external power supply 25 form a ground loop, the grounding point a and the grounding point b If there is a potential difference between the current and the current, a current flows through the ground loop. If a current flows through the ground loop, there is a possibility that the internal power supply circuit 23 or the drive circuit 24 malfunctions or a circuit element abnormality occurs.

  In order to solve the above problem, the circuit of FIG. 3 or FIG. 4 can be considered. In FIG. 3 and FIG. 3, the same circuit blocks as those in FIG.

  The drive control circuit 31 of FIG. 3 uses a three-terminal regulator 33 to separate the ground line G31 of the internal power supply circuit 23 and the ground line G32 of the drive circuit 24 on the control board 32 so that no ground loop is generated. Yes.

  The drive control circuit 41 in FIG. 4 separates the ground line G31 of the internal power supply circuit 23 and the ground line G32 of the drive circuit 24 by inserting the inductor L1 into the power supply line of the control board 42, so that no ground loop is generated. I am doing so.

  The drive control circuit 31 of FIG. 3 needs to mount the three-terminal regulator 33 on the control board 32, so that the number of parts increases and the mounting area of the board decreases by mounting the three-terminal regulator 33. There is a problem.

  The drive control circuit 41 of FIG. 4 has a problem that the mounting area of the board is reduced and the cost of the parts is increased because the size of the component of the inductor L1 mounted on the control board 42 is large.

Patent Document 1 discloses a gate charge recovery in which a capacitor is connected between a reference terminal of a gate drive semiconductor device and a positive terminal of a driver, and a filter resistor is connected between the positive terminal of the driver and the positive terminal of a voltage source. The circuit is described.
Japanese Patent Laid-Open No. 7-273626

  An object of the present invention is to prevent malfunction of a circuit on a substrate without increasing the component cost.

  A drive control circuit according to the present invention is a drive control circuit in which a power supply external to a substrate and a semiconductor element are connected by a wiring cable, and a circuit for supplying a drive signal to the semiconductor element is mounted on the substrate. A circuit, a drive circuit for generating a drive signal to be supplied to the semiconductor element, and a current limiting resistor inserted in a power supply line for supplying a power supply voltage from the internal power supply circuit to the drive circuit. The ground wiring of the internal power supply circuit and the ground wiring of the driving circuit were separated.

  According to the present invention, the ground wiring of the internal power supply circuit and the ground wiring of the drive circuit can be separated by inserting the current limiting resistor into the power supply line. The formation of a ground loop can be prevented. As a result, malfunction of the drive control circuit can be prevented.

  According to the present invention, malfunction of a circuit in the control board can be prevented.

Hereinafter, preferred embodiments of the present invention will be described. FIG. 1 is a diagram illustrating a main circuit element 17 that controls a current supplied to the drive control circuit 11 and the load 16 according to the embodiment.
The drive control circuit 11 is mounted on the control board 12 and includes an internal power supply circuit 13 including a smoothing capacitor C1 and a drive circuit 14 including a capacitor C2.

  A load 16 is connected to the positive electrode side of the external power supply 15 via a wiring cable CABLE 1, and a main circuit element (semiconductor element, MOS transistor, etc.) 17 is connected in series with the load 16. The ground side of the main circuit element 17 is connected to the negative electrode (ground) side of the external power supply 15 via the wiring cable CABLE2.

  One input of the internal power supply circuit 13 is connected to the positive electrode side of the external power supply 15, and the other is connected to the negative electrode side of the external power supply 15. A current limiting resistor R1 is inserted in the power supply line P1 that supplies the power supply voltage generated by the internal power supply circuit 13 to the drive circuit. One end of the current limiting resistor R1 is connected to the connection point between the output-side power supply line P1 and the smoothing capacitor C1 of the internal power supply circuit 13, and the other end is connected to the power supply line P1 connected to the drive circuit 14. The current limiting resistor R1 is for separating the ground line G1 that is the ground wiring pattern of the internal power supply circuit 13 and the ground line G2 that is the ground wiring pattern of the drive circuit 14. Further, by connecting the current limiting resistor R1 to the connection point between the smoothing capacitor C1 and the power supply line P1, the ground line G1 of the power supply circuit 13 including the smoothing capacitor C1 and the ground line G2 of the drive circuit 14 can be separated. it can.

  The input of the drive circuit 14 and the capacitor C2 are connected to the power supply line P1. The drive circuit 14 is a circuit that generates a drive signal for turning on and off the main circuit element 17 made of a MOS transistor or the like, and supplies the generated drive signal to the gate of the main circuit element 17. The ground line G <b> 2 of the drive circuit 14 is connected to an electrode (drain or source) on the low potential side of the main circuit element 17.

  Next, the operation of the circuit of FIG. 1 will be described. When a drive signal is supplied from the drive circuit 14 to the gate of the main circuit element 17, the main circuit element 17 performs a switching operation, and a current corresponding to the ON period of the drive signal flows. This current flows from the ground point a of the main circuit element 17 through the wiring cable CABLE2 to the negative electrode of the external power source 15 through the ground point b on the external power source 15 side. At this time, a potential difference is generated between the ground point a and the ground point b due to the inductance of the wiring cable CABLE2, but a current limiting resistor R1 is inserted into the power line P1, and the ground line G1 of the internal power circuit 13 and the drive circuit 14 are connected. Since the ground line G2 is separated, a ground loop is not formed. Therefore, the drive circuit 14 is not affected by the potential difference caused by the wiring inductance of the wiring cable CABLE2.

  According to the embodiment described above, by inserting the current limiting resistor R1 having a small resistance value (for example, several Ω) into the power line P1, the ground line G1 of the internal power circuit 13 and the ground line G2 of the drive circuit 14 are inserted. And a ground loop is not formed with the wiring cable CABLE2. Therefore, even if a potential difference occurs between the grounding point a and the grounding point b due to the influence of the wiring inductance of the wiring cable CABLE2, the ground line G1 and G2 of the control board 12 are separated, so that a current due to the ground loop is generated. Not flowing. Therefore, it is possible to prevent the drive control circuit 11 mounted on the control board 12 from malfunctioning. Further, since the current limiting resistor R1 to be used may be a resistor having a small resistance value, the power loss is small, and a small and inexpensive resistor can be used.

It is a figure which shows the drive control circuit and main circuit element of embodiment. It is a figure which shows the conventional drive control circuit and a main circuit element. It is a figure which shows the drive control circuit and main circuit element using a 3 terminal regulator. It is a figure which shows the drive control circuit and main circuit element which used the inductor.

Explanation of symbols

11, 21, 31, 41 Drive control circuit 12, 22, 32, 42 Control board 13, 23 Internal power supply circuit 14, 24 Drive circuit

Claims (2)

A power source outside the substrate and the semiconductor element are connected by a wiring cable, and a circuit for supplying a drive signal to the semiconductor element is a drive control circuit mounted on the substrate,
An on-board power circuit;
A drive circuit for generating a drive signal to be supplied to the semiconductor element;
A current limiting resistor inserted in a power supply line for supplying a power supply voltage from the internal power supply circuit to the drive circuit;
A drive control circuit in which a ground wiring of the internal power supply circuit and a ground wiring of the driving circuit are separated on a substrate.   The current limiting resistor has one end connected to a connection point between the power supply line on the output side of the internal power supply circuit and a smoothing capacitor, and the other end connected to the power supply line connected to the drive circuit. 1. The drive control circuit according to 1.

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