JPS62226654A - Semiconductor device - Google Patents

Abstract

PURPOSE:To form an electronic circut for effecting desiring circuit operations and to reduce operating errors due to a parasitic current by presetting the base potential level of a part or the whole of the electronic circuit formed in a semiconductor substrate to be higher than the earthing level. CONSTITUTION:A control circuit 4 controls a quantity of current of motor drive currents I1-I6 by a control signal Vs and accordingly controls a rotation velocity of a motor. A diode D1 is arranged between an earthing line l1 and an earthing point of the control circuit 4. A diode D is a parasitic diode and when a motor drive current is cut off, a parasitic element Q100 of an output circuit 3 gets into an on-state by a counter-electromotive force and a potential of an earthing line l2 increases by a parasitic current. Then, as if the control signal Vs were supplied to the circuit 4 through the diode D. However, the diode D1 prevents an influence of the parasitic current. Also, as there is a difference in voltage between the earthing line l1 and a signal transmission course, the circuit 4 is not operated by error before the potential of the earthing line l2 increases over the sum of a forward voltage and the voltage difference.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to electronic devices such as semiconductor integrated circuits in which various electronic circuits are formed on a semiconductor substrate, and particularly relates to electronic devices such as motors and inductive devices such as planshahn rhenoids. The present invention relates to circuit technology suitable for application to electronic devices that drive loads, and further to power integrated circuits (hereinafter referred to as ICs).

[Conventional technology]

Taking a motor drive circuit configured with a semiconductor integrated circuit as an example, when the drive current is interrupted, a back electromotive force is generated from the motor coil, and the voltage level at the output terminal becomes instantaneously high. Then, parasitic current (
Substrate current) flows.

Regarding the above parasitic elements, please refer to "Analog Integrated Circuits" (Fourth edition published February 1, 1980, Publisher: Kindai Kagakusha, I) p.
44-45).

The present inventors have studied malfunctions of electronic circuits formed in ICs due to parasitic currents. Although the following is not a publicly known technique, it is a technique that has been studied by the present inventors, and its outline is as follows.

The motor drive circuit includes a rotational position control system that controls energization of the motor coil, and a motor rotational speed control system. According to the present invention, when the parasitic current occurs, the potential of the substrate of the semiconductor substrate increases due to the separation resistance of the substrate, and an undesired control signal is supplied to the rotational position control system via the parasitic diode. This has been clarified through the examination of those involved. If the above-mentioned undesired control signal is generated, it is undesirable because it causes malfunction of the motor and destruction of the IC.

Therefore, attempts were made to improve the above-mentioned malfunction, but it turned out that it was difficult to eliminate the parasitic elements themselves due to the device structure.

The idea was to reduce the above-mentioned undesirable circuit operation using circuit technology.

[Problem that the invention seeks to solve]

In other words, when a parasitic current occurs, the potential of the substrate rises and a parasitic diode is interposed between the control signal transmission path and the substrate, causing a parasitic current to flow from the substrate to the transmission path. . This acts in the same way as a control signal, causing malfunction of the motor and destruction of the IC.

In order to reduce or prevent the above phenomenon, it has been realized that even if a parasitic current occurs, it should not affect the rotation control system.

If the potential of the ground line of the rotation control system is set higher than the ground point in advance, it is possible to block or reduce the current flowing from the parasitic diode to the rotation control system when a parasitic current occurs, thereby preventing the above phenomenon. I realized that I can get it.

An object of the present invention is to provide a semiconductor device in which an electronic circuit that performs a desired circuit operation is formed on a semiconductor substrate, and malfunctions caused by parasitic currents generated in the semiconductor substrate are reduced.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means for solving problems]

A brief summary of typical inventions disclosed in this application is as follows.

That is, an electronic circuit that performs the desired circuit operation is formed on a semiconductor substrate, a diode is connected between the ground line of the circuit and a ground point of the semiconductor substrate, and the potential of the ground line is set to the ground point of the diode. It is held at a high level in advance by a forward voltage difference.

[For production]

According to the above-mentioned means, the ground line of the electronic circuit has a high potential difference with respect to the ground point, and therefore the signal transmission path of the electronic circuit also has a high level with respect to the ground point, so that even if a parasitic current occurs, the signal from the parasitic diode is By reducing or blocking parasitic current flowing through the transmission path, malfunctions caused by parasitic current in electronic circuits formed on a semiconductor substrate are reduced. This achieves the object of the present invention.

〔Example〕

Hereinafter, one embodiment of an electronic device to which the present invention is applied will be described with reference to FIGS. 1 to 3. This embodiment shows an example in which the present invention is applied to a motor drive circuit, and FIG. 1 shows a basic circuit diagram, FIG. 2 shows a circuit diagram showing a specific example, and FIG. 3 shows a device structure. This is a cross-sectional view of the main parts of the IC.

The feature of this embodiment is that a motor drive circuit is formed on a semiconductor substrate, and it is configured to reduce malfunctions caused by parasitic current in the rotation speed control system.

First, the basic concept of the present invention will be explained with reference to FIG.

v1 to V are motor rotational position detection signals. Reference numeral 1 denotes a preamplifier, which amplifies the detection signals ①, .about.VS. 2 is a matrix circuit, and a switching key Va- determines the energization order of the motor coils L+-La based on the level difference of the amplified detection signals v,' to ■,'.
Obtain Vc.

3 is an output circuit, which obtains a drive current based on switching signals Va to Vc.

4 is a control circuit, which corresponds to the electronic circuit in the present invention.

The control circuit 4 controls the amount of motor drive currents I, to I6 based on the control signal Vs, and controls the rotational speed of the motor.

What should be noted here is that a diode D is provided between the ground line 1 of the control circuit 4 and the ground point.

Diode D indicated by a dotted line is a parasitic diode,
When the drive current supplied to the motor coils L1 to L is cut off, the parasitic element Q of the output circuit 3 is
+oo is turned on, and the potential of the ground line l increases due to the parasitic current.

The above parasitic elements will be described later with reference to FIGS. 2 and 3.

When the potential of the ground line l increases, the parasitic diode D
However, by providing the diode D, the influence of the parasitic current can be prevented.

That is, the potential of the ground line 1+ of the control circuit 4 is held by the diode D at a level higher than the ground point E by at least a level corresponding to the forward voltage.

Therefore, the ground line 1. Even if the potential increases due to parasitic current, if the level increase is less than the above forward voltage, then
Parasitic currents do not affect the control circuit 4.

Furthermore, since there is a voltage difference between the ground line h and the signal transmission path, if the potential of the ground line l does not rise beyond the potential difference determined by the sum of the forward voltage and the above voltage difference, the control circuit There is no way to cause 4 to 1 to malfunction.

By providing the diode D1 in this way,
Malfunctions of the control circuit 4 are reduced.

Next, a more detailed explanation will be given with reference to FIG. 2 and the third factor.

Hall elements H1 to H1 magnetically detect the rotational position of the motor to obtain the signals V, -V. 1a-1c
is a Hall amplifier, and obtains the above-mentioned signals v,1 to ■,'.

Although the matrix circuits 2a to 2c are provided individually for the signals v1' to v1' to v1,', since they have the same circuit configuration, the matrix circuit 2c will be explained.

Each of the output circuits 3a to 3c is configured as a push-pull circuit, and depending on the level of the signals Va-Vc, the power supply side transistor QitQs*QstQ? ,
Q--Qs and ground side transistor Q4*Q4+Q6 are selectively driven. Then, the driving currents flowing through the motor coils L1 to L are switched as shown in the figure.

The control circuit 4 obtains control signals vS' having mutually opposite phases from the control signal Vs, and since 4a+4b have the same circuit configuration, the control circuit 4a will be explained.

The control signal Vs and the reference voltage Vref are VS>V ref
In the case of , the transistor Q ls + Q s< is turned on, and the transistor Q + t w Q u is turned off. Then, the current mirror circuit composed of the transistors Q + sp Q ta becomes inactive.

The collector current of the transistor Qts is the transistor Ql
? is supplied to the base of the
Transistor Qta is turned off. Line 11. The voltage level of the control signal Vs' appearing in becomes low level.

On the other hand, the control signal Vs is input to the control circuit 4b.
1, the circuit operation opposite to the above is performed, the transistor corresponding to the transistor Qsm is turned on, and the control signal v appearing on line 1+t is
The voltage level of S' becomes high level.

The transistor Q+a and the transistor QCs of the matrix circuit 2c constitute a current mirror circuit, and the transistor corresponding to the transistor Q+a of the control circuit 4b and the transistor Q! of the matrix circuit 2c constitute a current mirror circuit. 6 constitutes a current mirror circuit.

When the control signal vs' changes in level as described above, the transistor QCs is turned off and the transistor QCs is turned on. Either one of the transistors Qts*Qt4 is turned on by the above-mentioned signals 2 and ', and the other is turned off.

Assuming that transistors Q, 4 are turned on and transistor Qta is turned off, the ground side transistor Q of the output circuit 3b is turned on, and the power side transistors Q, , Q, of the output circuit 3c are turned on. As a result, drive current III flows through the motor coil L. The above circuit operation is performed for each of the IJ circuits 2a to 2c, and the drive current is controlled as described above.

By the way, when the drive current is cut off, the coil L.

A back electromotive force is generated from ~L3, and the circuit operation at this time will be described using coil L1 as an example.

The voltage level of the No. 9 terminal increases to the power supply voltage V due to the back electromotive force e.
Parasitic P as shown as Q+oo when it rises above cc
NP) transistor turns on. Transistor Qsoo is formed on a semiconductor substrate as shown in FIG. The collector current of the transistor Q+m flows to the 13th terminal via the substrate resistor Rx, but since the potential of the P substrate increases, the line l+tK parasitic current tries to flow via the parasitic diode D.

However, the ground line l of the control circuits 4a, 4b.

A diode D is provided between the terminal 1 and the ground point referred to in the present invention, which is shown as terminal No. 13. Therefore, unless the potential of the P substrate rises to at least a forward voltage of 0.7 V or more, the parasitic diode D is difficult to turn on, and no parasitic current flows through the line to.

As a result, the level change of the line 1111111 corresponds to the level change of the control signal V s', the influence of parasitic current is reduced, and the above control is performed accurately.

The above parasitic current influence reduction operation is performed by coil IJI.

Since the same operation as described above is performed regardless of whether a back electromotive force is generated from either of L and L, malfunctions of the control circuits 4a and 4b are reduced, and the reliability of the motor drive circuit is improved.

(11) By forming an electronic circuit on a semiconductor substrate and by providing a diode between the ground line of the electronic circuit and the ground point of the semiconductor substrate to maintain the potential of the ground line at a high level in advance, Even if the potential increases due to parasitic current, the parasitic diode becomes difficult to turn on until the 70゛ potential reaches the forward voltage of the diode (0.7V), making it difficult for the electronic circuit to be affected by the parasitic current.
This effect provides the effect of reducing malfunctions of the electronic circuit.

(2) The above parasitic current is often generated by the back electromotive force generated when light is interrupted in one of the inductive loads.
The effect is that the reliability of the inductive load drive circuit can be improved.

(31) (1) (2+) has the effect of increasing the added value of electronic devices such as semiconductor integrated circuits.

Above, the invention made by the present inventor has been specifically explained based on the examples, but the present invention is not limited to the above examples, and can be modified in many ways without departing from the gist thereof. Needless to say, it is.

For example, the output circuit 3 may be configured by a Darlington-connected push-pull circuit. In this case as well, the parasitic transistor Q+oo appears in the output circuit as described above, so the same circuit operation as described above is performed for the control circuit 4. Although we have explained the case where it is applied to a drive IC, it is not limited to this, and it can be applied to plunger solenoid drive circuits, tape recorders, ■T
I' can be used for each m'a child device such as.

The present invention can be used at least in devices where parasitic elements occur, such as semiconductor integrated circuits.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions among the inventions disclosed in this document a is as follows.

That is, an electronic circuit is formed on a semiconductor substrate, a diode is provided between a ground line of the electronic circuit and a ground point of the semiconductor substrate, and a potential difference is maintained between the ground line and the ground point; This reduces the flow of parasitic current into the electronic circuit when the potential of the substrate increases due to the parasitic current, thereby reducing malfunctions of the electronic circuit due to the parasitic current.

[Brief explanation of drawings]

Figure 1 is a basic circuit diagram showing an embodiment of an electronic device to which the present invention is applied, Figure 2 is a circuit diagram of a motor drive circuit showing a specific example of the electronic device, and Figure 3 shows the generation of parasitic current. 2 is a cross-sectional view of the main parts of the illustrated IC. 1...Hall amplifier, 2...matrix circuit, 3.
...Output circuit, 4...Control circuit, Q1~QCs...
Transistor, Qlo. ...parasitic transistor, D,
... Diode, D... Parasitic diode, L1~L
,...Motor coil, Vs, Vs'...Control signal,
Va=Vc...Switching signal, P...Substrate. Agent: Patent Attorney Katsoo Ogawa Figure 1 Figure 3

Claims (1)

[Claims] 1. A semiconductor device in which the base potential level of part or all of an electronic circuit formed within a semiconductor substrate is set higher than a ground level.