JP3147656B2 - On / off control circuit for semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the operation of a semiconductor device, particularly a power semiconductor device which operates by receiving a power supply voltage for a load, by operating a semiconductor device connected to a high potential side from an on / off command from a low potential side. The present invention relates to an on / off control circuit for controlling the on / off control.

[0002]

2. Description of the Related Art In many cases, for example, a power device for driving an electric motor uses an inverter device which uses a DC voltage of several hundred V obtained by rectifying an AC voltage as a power source. Usually, a two-phase or three-phase configuration is used in which a so-called totem-pole connection circuit in which elements are arranged on a high voltage side and a low voltage side and turned on and off alternately is used as a unit.
In order to achieve the desired inverter function, it is necessary to give ON / OFF commands to the respective power semiconductor elements to operate them in the correct order.

The on / off command is, of course, a low voltage signal of about several volts which is issued from a drive control circuit or the like, and can be given as it is to the low voltage side power semiconductor element, but to the high voltage side power semiconductor element. On the other hand, it cannot be given unless the level of the reference potential is raised. For this reason, the transmission of the on / off signal to the high voltage side using a photocoupler has been widely performed. However, not only is the cost significantly increased, but also recently, the power semiconductor element and its control circuit have been used together with the power semiconductor element. When trying to incorporate them into the same chip, photocouplers became a bottleneck in integration.

As a means for solving this problem, there is known a technique of transmitting an on / off command to a high-voltage side power semiconductor element via a so-called level shift circuit. Referring to FIGS. The prior art will be described. FIG. 6 is a circuit diagram thereof, and FIG. 7 is a waveform diagram of related signals indicating the operation. FIG. 6 shows a circuit for one arm of the above-described totem pole connection, which is one phase constituting the power inverter device.

The right side of FIG. 6 shows a one-arm main circuit. In the example shown in the figure, semiconductor elements 1 and 2 which are npn-type insulated gate bipolar transistors are connected in series between a DC power supply voltage V and a ground potential E. An output terminal To for the load of the inverter device is derived from the interconnection point of the totem pole connection. As is well known, diodes 1a and 2a are respectively incorporated in these semiconductor elements 1 and 2 in parallel, and function as commutation diodes in the operation of the inverter device. Drive circuits 3 are provided corresponding to the semiconductor elements 1 and 2 to drive their insulated gates. Usually, power is supplied from a low-voltage control power supply 4 of about several volts.

On / off command S1 for semiconductor elements 1 and 2
And S2, as shown in FIGS. 7 (b) and 7 (a), specify ON and OFF, for example, in a high and low logic state, respectively, and mutually turn on and off both elements 1 and 2 as shown in FIG. It is generated with waveforms of almost opposite phases. The on / off command S2 for the low voltage side semiconductor element 2 may be given to the drive circuit 3 as it is as shown in FIG. 6, but the on / off command S1 for the high voltage side semiconductor element 1 needs to be transmitted to the high potential side HS. . For this purpose, a pulse generating circuit 21 is provided on the low-potential side LS, and the on-pulse Pn shown in FIG. 7C is generated according to the rise of the on-off command S1 from low to high, and the pulse is generated according to the fall from high to low. The 7 (d) off pulse Pf is output to the gate of the corresponding transistor 22.

Both transistors 22 receive a high voltage from the high potential side HS and are connected to the ground E via a resistor 23, and are turned on by an on-pulse Pn and an off-pulse Pf.
When the current set by 23 flows, a negative pulse-like ON command Sn and OFF command Sf are generated in the corresponding detection resistor 31 on the high potential side HS as shown in FIGS. 7 (e) and 7 (f), respectively. The Zener diode 32 connected in parallel to each detection resistor 31 is for keeping the pulse height of these commands Sn and Sf constant at all times.

The ON command Sn and the OFF command Sf on the high potential side HS corresponding to the ON / OFF command S1 on the low potential side LS for the semiconductor element 1 are obtained in the form of pulses. From these, the set command Ss shown in FIG. 7G and the reset command Sr shown in FIG.
And the flip-flop 42 is set / reset by these pulse commands, and its Q output is given to the drive circuit 3 as an on / off command SIH shown in FIG. 7 (i). The on / off command SIH of the high potential side HS is shown in FIG.
This is the same waveform as the on / off command S1 of the low potential side LS.

[0009]

According to the above-mentioned prior art, the on / off command S1 of the low potential side LS can be transmitted to the high potential side HS by using the level shift circuit instead of the photocoupler, and the on / off state can be achieved. By dividing the command S1 into an on-pulse Sn and an off-pulse Sf and operating the transistor 22 only for a short time, the power consumption required for transmitting the command can be very small. However, the potential difference between the high potential side HS and the low potential side LS, which was insulated by the photocoupler, is borne by the level shift circuit, so that the transistor 22 must have a high withstand voltage. However, there is a problem that a very large chip area is required for assembling the semiconductor device.

The transistor 22 has a power supply voltage V
Although a withstand voltage of about twice is originally required, when driving an inductive load such as an electric motor with the semiconductor elements 1 and 2, a spike voltage generated when the load current is rapidly cut off is applied to the output terminal To or overlaps with the power supply voltage V. You have to look at the room for it. Therefore, when the power supply voltage V is 20
The transistor 22 requires a withstand voltage of about 600 V at 0 V and about 1200 V at 400 V. Further, in order to transmit the ON / OFF command S1 separately to the ON pulse Sn and the OFF pulse Sf in order to save power consumption, two level shift circuits, and thus two transistors 22, are required. Further, since the load is actually driven in two or three phases, two to three arms, and thus four to six transistors 22, are required, and a considerable part of the area of the chip for the integrated circuit is occupied by this. The fact is that it is done.

In view of the above problems, an object of the present invention is to provide a semiconductor element on / off control circuit capable of saving a chip area required for assembling into an integrated circuit while keeping power consumption as low as possible. .

[0012]

According to the on / off control circuit of the present invention, the above object is achieved by providing a single semiconductor device provided between the high potential side and the low potential side for each semiconductor element to be turned on / off on the high voltage side. A current path, and switching means for controlling the current flowing through the current path on the low potential side in accordance with the on / off command,
Switching is performed by using current detection means for detecting the state of current flowing in the current path on the high potential side, and conversion means for converting a detection signal from the current detection means into a high potential side ON / OFF command for driving the semiconductor element. Means to make the current flow to the current path different according to the specified state of the on / off command on the low potential side, and to allow the conversion means to distinguish the specified state of on and off from the detection signal that changes according to the current while detecting the detection signal. Is converted into a high-potential-side ON / OFF command.

The present invention can be applied to a case where the semiconductor element in the above configuration is an insulated gate control thyristor capable of turning off a gate, in addition to an insulated gate bipolar transistor and a field effect transistor. In addition to the case where an ON / OFF command for specifying the ON / OFF state based on the logic state of high or low is given to these as usual, the case where the ON / OFF command is divided into an ON command and an OFF command and given, for example, in the form of a pulse, respectively. Also, the present invention can be easily applied.

In the present invention, in order to reduce the power consumption, it is advantageous to supply a pulse current to the current path by the switching means in the same manner as in the prior art. Since only one current path is used for each of the semiconductor elements, it is necessary to make the flow of current therethrough different depending on the ON / OFF designation state of the ON / OFF command on the low potential side.

In an advantageous embodiment of the present invention for this purpose, the switching means applies a pulse current having a different current value to the current path in accordance with the direction of change of the specified state of the low-potential-side ON / OFF command. The value signal is transmitted from the low potential side to the high potential side via the current path, and the detection signal of this pulse current by the current detection means is converted by the conversion means from the difference between the peak values reflecting the current value of the pulse contained therein. The signal is converted into a high voltage side ON / OFF command while distinguishing between the ON designated state and the OFF designated state. In this case, it is preferable to incorporate a threshold operation circuit element, for example, two inverters having different operation thresholds, into the conversion means in order to discriminate the difference between the pulse peak values.

In another embodiment for the above, according to one of the logic states of the low potential side ON / OFF command by the switching means, a pulse current is repeatedly and periodically passed through the current path, and the detection signal by the current detection means is provided. Is converted into a high voltage side ON / OFF command while distinguishing the ON / OFF designated state from the continuous state of the repetitive pulse by the converting means. In this case, the conversion means incorporates a so-called retriggerable one-shot circuit that generates a pulse having a pulse width longer than the repetition period of the pulse current. It is advantageously taken as an on / off command on the side.

Another means for making the manner in which the current flows into the current path according to the on / off designation of the low-potential-side on / off command while suppressing power consumption in the same manner as described above is the power inverter device. Utilizing the fact that the low-voltage side and high-voltage side semiconductor elements are turned on and off alternately, a current flows through the current path only when the low-potential-side on / off command is in the off state by the switching means, and a detection signal by the current detection means Is converted into a high-potential-side ON / OFF command by setting the state when the current flows as a designated OFF state. In this embodiment, the semiconductor element on the low voltage side is substantially on while the current is flowing through the current path, and a very small potential difference equal to the forward voltage of the semiconductor element is applied between the high potential side and the low potential side. Since it is not used, power consumption can be reduced.

[0018]

According to the present invention, the current path of the level shift circuit for transmitting the ON / OFF command from the low voltage side to the high voltage side is made single for each of the high voltage side semiconductor elements as described in the configuration of the preceding paragraph. By using only one transistor in the switching means corresponding to the transistor 22 of FIG. 6 for flowing, the number of transistors requiring a high withstand voltage is reduced to half of the conventional one. However, since it is necessary to transmit the two designated states of the ON / OFF command through this single current path, the present invention focuses on the point that the current paths can be used in time, and the current path can be selectively used. As described in the configuration described in the preceding section, the way in which the current flows is made different depending on the on / off designation state by the on / off command on the low potential side. This current control is performed by the switching means on the low potential side, and the high potential side converting means reproduces the on / off command while distinguishing the on / off designation state from the state where the detection signal by the current detecting means changes according to the current. Let it.

Further, in the present invention, it is necessary to reduce the power consumption of the level shift circuit as much as possible. As a means for this, as in the prior art, the current flowing in the current path is pulsed to reduce the power consumption time. Can be. Further, as another means for this purpose, when the high-voltage side and the low-voltage side semiconductor elements are turned on and off alternately, the current flows through the current path only when the on-off command for the high-voltage side semiconductor elements is in the off designation state. The level of power consumption can be reduced by minimizing the potential difference between the high potential side and the low potential side during the time when the current flows.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of an embodiment of an on / off control circuit according to the present invention and waveform diagrams of related signals, FIG. 2 is a circuit diagram of a different embodiment, FIG. 3 is a waveform diagram of related signals of FIG. 2, and FIG. FIG. 5 is a circuit diagram of the embodiment, and FIG. 5 is a waveform diagram of related signals in FIG. 4. The same reference numerals are given to the portions corresponding to FIG. 6 and FIG. And In these embodiments, all the semiconductor elements to be on / off controlled are insulated gate bipolar transistors. However, the circuit of the present invention is not limited to this and can be applied to on / off control of various semiconductor elements.

In the embodiment described below, the main circuit including the semiconductor elements 1 and 2 is the same as that of FIG. 1 described above as shown in FIG. And a control power supply 4 for supplying power thereto, and ON / OFF commands S1 and S2 for switching between high and low are respectively shown in FIG. 1 (c) and FIG.
The same applies to the points given by waveforms of opposite phases as shown in (b). However, the circuit of the present invention differs from the conventional circuit in that a single current path 10 is used as a transmission path from the low potential side LS to the high potential side HS of the ON / OFF command S1 for the high-voltage side semiconductor element 1 as shown in the figure. .

In the present invention, the current flowing through the current path 10 is controlled by the switching means 20 of the low potential side LS so as to flow differently according to the ON / OFF designation state of the on / off command SI, and the current of the high potential side HS is controlled. The detection means 30 detects this current and generates a detection signal Sd that changes according to the flow of the current.The conversion means 40 distinguishes the detection signal Sd from the on-designation state and the off-designation state while distinguishing between the ON designation state and the OFF designation state. 1 is converted into an ON / OFF command S1L on the high potential side HS for driving the driving circuit 1 and is supplied to the driving circuit 3.

In the embodiment shown in FIG. 1A, the switching means 20 causes the pulse current to flow through the current path 10 with different current values in accordance with the high or low state change direction of the on / off command S1. In FIG. 21, a common pulse Pc is generated as shown in FIG. 1 (d) each time the high and low states of the on / off command S1 change, and an off pulse Pf is generated as shown in FIG. 1 (e) in accordance with the change from high to low. Generate as shown.
For this purpose, for example, two one-shot circuits are provided in the switching means 20 and one of them is operated when the on / off command SI rises and the other is when the on / off command SI rises, and both outputs are connected to the common pulse Pc via the OR gate. And the other output may be taken out as the off-pulse Pf. In some cases, the on-pulse Pn in FIG. 6 may be generated instead of the off-pulse Pf.

In addition, two transistors 22 and 24 are incorporated in the switching means 20.
Reference numeral 22 denotes a high-withstand-voltage transistor inserted into the current path 10, in which two resistors 23a and 23b are connected in series on the ground side, and a transistor 24 is connected in parallel with one of the resistors 23b. Are supplied with a common pulse Pc, and the latter with an off-pulse Pf. Therefore, when the common pulse Pc and the off-pulse Pf are simultaneously generated, the transistor 22 is connected to the resistor 23a.
A large pulse current flows through the current path 10 using only the source resistance as the source resistance, and when only the off pulse Pf is generated, the resistances 23a and 23
A small pulse current is passed using b as a source resistance. The transistor 22 operates as a so-called source-follower-connected transistor, and accurately controls the large and small pulse currents to be passed through the current path 10 to a constant value as set by the source resistance. Note that the current value ratio of these large and small pulse currents is 2
It is desirable to set above.

The current detecting means 30 on the high potential side HS includes a detecting resistor 31 inserted into the current path 10 as in the case of FIG.
A zener diode 33 is connected in parallel with this, and a detection signal Sd for detecting the above-mentioned large and small pulse currents flowing in the current path 10 is generated with a waveform including large and small negative pulses as shown in FIG. . As can be seen from this waveform, the Zener diode 33 of this embodiment is not used for stabilizing the pulse waveform in the detection signal Sd as in the conventional case, but is used for protecting the conversion unit 40 from overvoltage, so that the Zener breakdown voltage is higher than the conventional case. Things are used. The pulse waveform is stabilized by the above-described source follower operation on the transistor 22 side.

The conversion means 40 on the high potential side HS outputs the detection signal Sd
The pair of inverters 41 whose operating thresholds are different from each other
Received at c and 41f. The threshold value of the inverter 41c is lower than that of the inverter 41c, so that the common pulse Sc shown in FIG.
Is formed with the same waveform as the common pulse Pc. The inverter 41f having the higher threshold generates the off pulse Sf shown in FIG. 1H with the same waveform as the off pulse Pf shown in FIG. 1E. A reproduction circuit that receives these so-called reproduction pulses Sc and Sf
43 reproduces the on / off signal S1H on the high potential side HS shown in FIG. 1 (i) with the same waveform as that of FIG. 1 (b) while distinguishing the on / off designation state by the on / off signal S1.

At the time of this reproduction, the ON operation is specified by the high of the common pulse Sc and the low of the OFF pulse Sf, and the OFF operation is specified by the high of both the pulses. Two logic gates, one for each output high in the specified state, and one
A plurality of flip-flops may be provided, and the flip-flop may be set as the output of one logic gate and reset with the output of the other logic gate, and the Q output thereof may be taken out as the on / off signal S1H.

As can be seen from the above, in the embodiment of FIG. 1, the switching means 20 of the low potential side LS is connected to the single current path 10.
A pulse current having a different current value flows in accordance with the direction of change of the logic state of the on / off command S1.The current detection means 30 on the high potential side HS generates a detection signal Sd of this pulse current, and the conversion means 40 generates the detection signal Sd. The on / off signal S1H can be reproduced on the high potential side HS while accurately discriminating the designated state of on / off from the difference between the peak values of the pulse reflecting the current value of the pulse current. Further, since the current flows through the current path 10 in a pulse form only for a very short time, power consumption is very small.

In the next embodiment shown in FIG. 2, the flow of the pulse current through the current path 10 is the same as that of the previous embodiment, except that the ON / OFF command S1 flows the repetitive pulse current only during the time when one of the logic states is taken. different. For this reason, a pulse generating circuit 25 is incorporated in the switching means 20 so that the on / off command S1 shown in FIG.
In this example, the repetitive pulse Pr is generated as shown in FIG. The repetition period is set within a range of, for example, one tenth to several tenths of the period of the on / off command SI. Transistor 22 receiving this repetitive pulse Pr
Flows a repetitive pulse current through the current path 10 at a current value set by the resistor 23, and keeps the value constant by the above-described source follower operation.

The current detecting means 30 on the high potential side LS comprises a resistor 31 and a Zener diode 32. As shown in FIG. 3D, the detection signal Sd has a waveform including a plurality of negative pulses corresponding to the repetitive pulse Pr described above. Occurs in In this embodiment, the peak value of the negative pulse can be made constant by the Zener diode 32. The conversion means 40 receives the detection signal Sd and issues an ON / OFF command from the continuation and interruption of the repetitive pulse included in the detection signal Sd.
High potential side while discriminating between ON and OFF designated states by SI
Create HS on / off command S1H. For this reason, in the embodiment of the drawing, a retriggerable one-shot circuit is used as the conversion means 40.
44, the width of the generated pulse is set slightly longer than the repetition period of the pulse current flowing through the current path 10, and the output is output while repeatedly triggering the operation by the pulse in the detection signal Sd. It is taken out as the on / off command S1H shown in 3 (e). As can be understood from the above description, in the embodiment of FIG. 2, the repetitive pulse current is applied to the current path 10, so that the power consumption is slightly increased as compared with the previous embodiment, but the circuit configuration can be considerably simplified.

In the embodiment shown in FIG. 4, a pulse current is supplied to the current path 10 as in the previous embodiments by utilizing the fact that the semiconductor element 1 on the high voltage side and the semiconductor element 2 on the low voltage side alternately turn on and off. Instead of flowing, a continuous current flows during the time when the ON / OFF command S1 is in the OFF designated state. That is, in the switching circuit 20 of the embodiment shown in FIG. 4, the auxiliary command S1I shown in FIG.
5D, the current i is continuously supplied to the current path 10 during the time when the ON / OFF command S1 is designated as OFF as shown in FIG. 5D, and in the example shown in FIG. Shed.

While the current i is flowing, the output terminal To, which is the reference potential on the high potential side HS, is substantially the same potential as the ground point E because the low voltage side semiconductor element 2 is on.
Since only about the voltage of the control power supply 4 is applied between the upper and lower ends of the power supply 10, power consumption is small even with a continuous current. In addition,
Since the semiconductor elements 1 and 2 are both turned off at the beginning of the flow of the current i, a peak current ip is generated as shown in FIG. 5 (d), but the current consumption is not so great because it is a short time of about 2 to 3 μS. The current detecting means 30 on the high potential side HS has the same configuration as the embodiment of FIG. 2, and the detection signal Sd has a waveform similar to the on / off command S1 as shown in FIG. 5 (e). Therefore, if the detection signal Sd is amplified to a desired level using the simple amplification circuit 45 for the conversion means 40, the on / off command S1H of the high potential side HS that sets the state in which the current flows in the current path to the off designation state
Is obtained.

As described above, in the embodiment of FIG. 4, the circuit configuration can be further simplified as compared with the embodiment of FIG. 2 while suppressing the current consumption, and the reliability of the operation of the control circuit is higher than that of the embodiment of FIGS. Can be enhanced. That is, when the flip-flop in the reproduction circuit 43 shown in FIG. 1A is set or reset by mistake due to the contamination of the control circuit, or when the repetitive trigger of the one-shot circuit 44 shown in FIG. Since the waveform of the ON / OFF command S1H on the high potential side HS is disturbed, in the worst case, the semiconductor elements 1 and 2 may be turned on at the same time to short-circuit the power supply voltage V. However, in the embodiment of FIG.
Since a continuous current flows through 10, there is almost no risk of adverse effects of noise.

[0034]

According to the present invention, even if a single current path for transmitting the on / off command from the low voltage side to the high voltage side is provided for each of the high-voltage side semiconductor elements, the ON / OFF command state can be obtained by selectively using them in time. Focusing on the point that the potential can be transmitted, as described above, the way of flowing the current in the current path is changed by the low-potential side switching means according to the ON / OFF designation state by the low-potential side ON / OFF command, and the high-potential side This current is detected by the current detection means on the side to generate a detection signal, and the conversion means changes the detection signal according to the flow of the current. Since the on / off command is reproduced, only one high-breakdown-voltage transistor for controlling the current flowing in the current path is required. It is possible to save the chip area necessary for incorporating.

It is to be noted that a pulse current having a different current value is supplied to the current path in accordance with the direction in which the designated state of the on / off command changes between on and off, and the difference between the peak values of the pulses in the detection signal reflecting this current value is determined. The embodiment of the present invention in which the ON / OFF command is reproduced while discriminating the designated state of ON or OFF, and the embodiment in which a threshold operation circuit element such as an inverter is used for discriminating the ON or OFF state, allows the pulse current to flow in the current path for a very short time. This has the effect of reducing the power consumption of the control circuit. Also,
A mode in which a repetitive pulse current is caused to flow in a current path according to one of the logical states of the ON / OFF command to distinguish an ON / OFF designated state from a continuous state of the repetitive pulse in the detection signal, and further, triggered repeatedly by the repetitive pulse The mode of reproducing the on / off command by the one-shot circuit has an effect of reducing power consumption and simplifying a circuit configuration.

Further, by utilizing the fact that the low-voltage side and high-voltage side semiconductor elements are turned on and off alternately, a current flows through the current path only when the low-potential side on-off command is in the off-designating state.
The mode of reproducing the on / off command with the current flowing time being designated as the off state has the effects of further simplifying the circuit configuration while suppressing power consumption and further improving the operational reliability of the on / off control circuit.

The on / off control circuit of the present invention having the above-described features is a single semiconductor control circuit for a power semiconductor element incorporated in a two-phase or three-phase arm of a power inverter device for driving a motor or the like. It is particularly effective when incorporated into a chip or when incorporated into a chip for a semiconductor device, and is extremely effective in significantly reducing the chip size of this type of integrated circuit and improving economic efficiency. .

[Brief description of the drawings]

FIGS. 1A and 1B show a circuit diagram of an embodiment of the present invention and waveforms of related signals. FIG. 1A is a circuit diagram thereof, and FIG. 1B is a waveform diagram of an ON / OFF command for a low voltage side semiconductor device. Figure (c) is a waveform diagram of a low potential side on / off command for the high voltage side semiconductor element,
(D) is a waveform diagram of a common pulse in the switching means,
(E) is a waveform diagram of the off pulse in the switching means,
(F) is a waveform diagram of a detection signal by the current detection means, and FIG.
(g) is a waveform diagram of a common pulse in the converter, FIG. (h) is a waveform diagram of an off-pulse in the converter, and (i) is a waveform diagram of a high-potential-side on / off signal for the high-voltage side semiconductor element. It is.

FIG. 2 is a circuit diagram of another embodiment of the present invention.

3A and 3B show waveforms of related signals in FIG. 2; FIG. 3A is a waveform diagram of an on / off command for a low voltage side semiconductor element; FIG. 3B is a low potential side on / off state for a high voltage side semiconductor element; (C) is a waveform diagram of a repetitive pulse in the switching means, (d) is a waveform diagram of a detection signal by the current detection means, and (e) is a waveform diagram of the high voltage side semiconductor element. FIG. 7 is a waveform diagram of an on / off signal on the potential side.

FIG. 4 is a circuit diagram of still another embodiment of the present invention.

5A and 5B show waveforms of related signals in FIG. 4; FIG. 5A is a waveform diagram of an on / off command for a low voltage side semiconductor element, and FIG. 5B is a low potential side on / off state for a high voltage side semiconductor element; (C) is a waveform diagram of the complementary signal of the ON / OFF command in switching, (d) is a waveform diagram of the current flowing in the current path, and (e) is a detection signal by the current detecting means. FIG. 4 is a waveform diagram of a high-potential-side on / off signal for a high-voltage-side semiconductor element.

FIG. 6 is a circuit diagram of a conventional on / off control circuit.

7A and 7B show waveforms of related signals in FIG. 6; FIG. 7A is a waveform diagram of an ON / OFF command for a low voltage side semiconductor element; FIG. 7B is a low potential side ON / OFF for a high voltage side semiconductor element; (C) Waveform diagram of ON pulse, (d) Waveform diagram of OFF pulse, (e) Waveform diagram of ON command, same diagram
(f) is a waveform diagram of an OFF command, FIG. (g) is a waveform diagram of a set command, FIG. (h) is a waveform diagram of a reset command, and FIG. It is a waveform diagram of an on-off signal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High voltage side semiconductor element 2 Low voltage side semiconductor element 3 Drive circuit for semiconductor element 4 Power supply of control circuit 10 Current path 20 Switching means 22 High breakdown voltage transistor 30 Current detection means 40 Conversion means 41c, 41f Operating thresholds are different Inverter 43 Regeneration circuit of conversion means 44 Retriggerable one-shot circuit of conversion means 45 Amplifier circuit of conversion means HS High potential side i Current flowing through current path LS Low potential side Pc Low potential side common pulse Pf Low potential side off pulse Pr Repetitive pulse Sc High-potential common pulse Sd Detection signal by current detection means Sf High-potential side off pulse S1 Low-voltage on / off command for semiconductor device 1 S1H High-voltage on / off command for semiconductor device 1 S2 Semiconductor device 2 ON / OFF command for low voltage side

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H03K 17/00-17/70

Claims (7)

(57) [Claims] A control circuit for operating a high-potential-side semiconductor element in response to a low-potential-side on / off command, provided between the high-potential side and the low-potential side for each semiconductor element to be turned on / off. A single current path, switching means for controlling the current flowing in the current path in accordance with the ON / OFF command on the low potential side, current detection means for detecting the current in the current path on the high potential side, and detection by the current detection means Conversion means for converting the signal into a high-potential-side on / off command for driving the semiconductor element, and switching the current in the current path by the switching means according to a designated state by the low-potential-side on / off command. The detection signal is converted into a high-potential on / off command while distinguishing between an on-designation state and an off-designation state from a detection signal that changes according to the current by the conversion means. Off control circuit of a semiconductor device characterized. 2. The control circuit according to claim 1, wherein a pulse current is caused to flow in the current path by the switching means. 3. The control circuit according to claim 2, wherein the switching means causes a pulse current having a different current value to flow through the current path in accordance with the direction of the state change of the on / off command on the low potential side, and the pulse current of the pulse current is supplied to the conversion means. An on / off control circuit for a semiconductor element, characterized in that an on-designation and an off-designation are distinguished from a difference between peak values of a pulse in a detection signal reflecting a current value. 4. The control circuit according to claim 3, wherein a threshold operation circuit element is incorporated in the conversion means so as to discriminate the difference between the peak values of the pulses in the detection signal. ON / OFF control circuit. 5. The control circuit according to claim 2, wherein the switching means repeatedly supplies a pulse current to the current path in a constant cycle in accordance with one of the logical states of the low-potential-side ON / OFF command, and detects the pulse current in the conversion means. An on / off control circuit for a semiconductor device, characterized in that an on designated state and an off designated state are distinguished from a continuous state of a repetitive pulse in a signal. 6. The control circuit according to claim 5, wherein a one-shot circuit for generating a pulse having a pulse width longer than the repetition period of the pulse current is incorporated in the conversion means, and the operation is repeatedly triggered by a pulse in the detection signal. And outputting the output as a high-potential-side ON / OFF command. 7. The control circuit according to claim 1, wherein the on / off of the low-voltage side and high-voltage side semiconductor elements is alternately operated, and the current is supplied when the low-potential-side on / off command is set to an off state by the switching means. An on / off control circuit for a semiconductor element, wherein a current is caused to flow in a path, and a detection signal is converted into a high-potential-side on / off command by a conversion means by setting a state when the current flows as an off designation state.