JP2001339986A - Semiconductor device for motor drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress maloperation by parasitic current when shutting down a power source supply voltage by reducing the influence by parasitic transistors. SOLUTION: Maloperation of a head actuator control circuit is suppressed by suppressing parasitic current by making a parasitic PNP transistor in an off state by connecting a N-type semiconductor domain of a dispersed resistor 25 and a N-type semiconductor domain 26 which does not form element to a node 37 which takes out by rectifying three-phase induced electromotive force generated by rotation inertia of a motor, when the power supply voltage is shut down.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device for driving a motor.

[0002]

2. Description of the Related Art A semiconductor device for driving a magnetic disk motor will be described below as an example of a semiconductor device for driving a motor. In recent years, semiconductor devices for driving magnetic disk motors have
With the advance of chipping, driving of a motor for rotating a magnetic disk as a recording medium, driving of a head actuator for moving a head for reading and writing data, and driving of a head actuator for moving the head to a retracted position when power supply voltage is cut off. Driving and three functions have been performed by one chip.

[0003] Each function will be described below.
A power control circuit of a normal magnetic disk drive will be briefly described with reference to FIG. The motor 2 and the head actuator 3 for moving the read-write head are driven by the push-pull power stage from the power supply line 1 at, for example, 12V. The motor 2 is driven by three branches U, V and W, each having two power elements S1 and S2, S3 and S4, S5 and S6. Branch U,
The power stage consisting of V and W is controlled by the motor control circuit 4. The motor control circuit 4 outputs appropriate control signals via the connection lines 14 to 19 to the power elements S1 to S6.
And a predetermined rotation speed of the motor 2 is obtained. Resistance R
S1 is a low resistance value, and all the current flowing through each phase of the motor 2 flows through this resistance RS1. The voltage generated between both ends of the resistor RS1 is amplified by the amplifier 7, and then supplied to the input terminal 8 of the motor control circuit 4.

Next, the head actuator 3 is driven by another bridge-type power stage. This power stage has two branches N and P, each of which comprises two series-connected power elements S7 and S8, S9 and S1.
Has zero. This power stage is controlled by the head actuator control circuit 5. The head actuator control circuit 5 outputs a control signal for moving the head to a position where data is read from the disk or written to the disk via the connection lines 20 to 23. A detection resistor RS2 is connected to the head actuator 3, and a voltage multiplied by the resistance value of the current flowing through the head actuator 3 is generated between both ends of the resistor.
2 and supplied to the input terminal 13 of the head actuator control circuit 5. The value of the current flowing through the head actuator 3 is controlled by the head actuator control circuit 5.

Third, the head actuator retracting function will be described. The power supply voltage inside the semiconductor device for driving the magnetic disk motor rapidly decreases to the ground voltage when the power supply is cut off. At this time, generally, before the disk stops, it is outside the disk area where data is stored, that is,
The head is moved to a position where data is not damaged by the head coming into contact with the disk surface when the disk speed is reduced. Therefore, even when the head actuator 3 moves in the direction opposite to the retreat position when the power is turned off, a current is required to move the head actuator 3 completely to the retreat position. For this purpose, electric power is generated using kinetic energy due to the inertial rotation of the motor 2, and the head actuator 3 is moved to the retracted position using the induced electromotive force. In order to realize this function, it is usually necessary to provide a separating device such as a transistor 11 so that the current generated from the motor 2 does not return to the power supply line 1 which is 0 V in this case. .

[0006] The power supply voltage detection circuit 6 changes the operation mode of the motor control circuit 4 and the head actuator control circuit 5 immediately upon detecting the power supply voltage drop below a specific value. Actually, the power supply voltage detection circuit 6 is provided with a plurality of power supplies used in the magnetic disk device, for example, 12V,
The three power supply voltages of 5 V and 3.3 V are detected, and when any one of them becomes lower than a specific voltage, a command to change the operation mode is sent to the motor control circuit 4 and the head actuator control circuit 5 through the connection line 9. Communicate through.

A conventional semiconductor device for driving a magnetic disk motor will be described below. FIG. 3 is a diagram showing the connection between the motor 2, the head actuator 3, and the semiconductor device for driving the magnetic disk motor. Reference numeral 11 denotes a separating transistor that cuts off conduction between the power supply and the semiconductor device for driving the magnetic disk motor when the power supply voltage is cut off. , S1 to S6 are power elements for driving the motor, 27 to 29 are connection points between each phase of the motor and the semiconductor device for driving the magnetic disk motor, and S7 to S10 are power elements for driving the head actuator 3. These power elements S1-S6 can take various forms, but are preferably N-channel DMOS transistors, which are actually one of the most suitable types of transistors in this field. Similarly,
Four power elements S composed of DMOS transistors
7 to S10 constitute a power stage for driving the head actuator 3. In addition, the isolation for power supply voltage is also DMOS
Provision is made by transistor 11 to minimize the series voltage drop in the power supply when the power supply voltage is present. The conduction command for the separating DMOS transistor 11 can be given by a power supply voltage detection circuit (see the power supply voltage detection circuit 6 in FIG. 2).

The operation of the semiconductor device for driving a magnetic disk motor configured as described above when the power supply voltage is cut off will be described below with reference to FIG. 37 is branch 27,28
And 29 at the power supply side common connection point (hereinafter referred to as node 37), the potential of which is the same as the highest potential of the branches 27, 28 and 29. First, when the power supply voltage is cut off, the power supply voltage detection circuit (see the power supply voltage detection circuit 6 in FIG. 2) detects that the power supply voltage has been cut off, and turns off the separation DMOS transistor 11.
The path from 7 to the power supply is completely insulated by 11 DMOS transistor-specific diodes, and the path from the connection points 27 to 29 between the phases of the motor 2 and the semiconductor device for driving the magnetic disk motor to the ground point is also S1, Insulated by DMOS specific diodes of S4 and S5. As a result, the three-phase induced electromotive force generated by the motor 2 is rectified by the DMOS-specific diodes S2, S3, and S6 and supplied to the node 37. At this time, the head actuator control circuit 5 when the power supply voltage is cut off controls S7 and S9 to supply a current to the head actuator 3 and move the head actuator 3 to a desired retreat position.

Further, D of S7 and S9 when the power supply voltage is cut off
The operation of the control circuit of the MOS transistor will be briefly described with reference to a specific circuit example. FIG. 6 shows an example of the head actuator control circuit 5. When the power supply voltage is present, the isolation DMOS transistor 11 is in a high conduction state, and the external capacitor 38 is charged to a voltage lower than the power supply voltage by the forward voltage of the diode 48. When the power supply voltage is cut off, the power supply voltage detection circuit 6 detects that the power supply voltage has been cut off,
OS transistor 11 and switch transistors 39-4
Turn 1 off. Then, the gate of the DMOS transistor S9 on the branch P side is biased through the diode 49, the diffusion resistor 50, and the diode 53, so that S9 becomes highly conductive and the voltage of the branch P becomes about 0V. Here, the diffusion resistance 50
Is a high resistance provided to hold the residual charge of the external capacitor 38 for a long time, and limits the amount of current flowing into the circuit from the external capacitor 38.

On the other hand, the DMOS transistor S on the branch N side
Reference numeral 7 denotes external resistors 44 and 45, a diffusion resistor 43, an NPN transistor 42, diodes 56 and 52, and a path 4
6, and the voltage of the branch N is calculated as follows: Vn = Vbe42 × (1 + R44 / R45 + R44 / R
43) Here, Vn: voltage of branch N Vbe42: Vbe of NPN transistor 42 R43: resistance value of diffusion resistance 43 R44, R45: resistance value of external resistances 44, 45 A current flows in a direction toward the branch P, and movement to the retreat position is performed.

As described above, after the power supply voltage is shut off in this circuit, the gate bias circuits of the DMOS transistors S7 and S9 are driven by the residual charge of the external capacitor 38.

Hereinafter, problems in this configuration will be described with reference to the drawings. FIG. 4 is a diagram schematically showing a semiconductor section of a conventional semiconductor device for driving a magnetic disk motor.
Is the N-channel DM on the ground side of the branches 27, 28 and 29.
OS transistor (hereinafter, ground-side N-channel DM
A drain N-type semiconductor region of the OS transistor);
25 is a diffusion resistance, and 26 is an N-type semiconductor region where no element is formed. After the power supply voltage is cut off, the rotation control of the motor by the magnetic disk motor driving semiconductor device is not performed. Therefore, the voltages at the connection points 27 to 29 (see FIG. 3) between each phase of the motor 2 and the magnetic disk motor driving semiconductor device are changed. As shown in FIG. 5, a section in which the motor 2 has a negative potential occurs due to the inertial rotation of the motor 2. This negative potential is a voltage determined by the unique diodes of S1, S4 and S5 (see FIG. 3). The parasitic transistor 30,
31 occurs. The parasitic transistor 30 is composed of an N-type semiconductor region (emitter) on the drain side of the N-channel DMOS transistor on the ground side, a P-type semiconductor substrate (base), and an N-type semiconductor region (collector) of the diffusion resistor 25.
The parasitic transistor 31 becomes a parasitic PNP transistor with the diffusion resistor 25 (P-type semiconductor emitter), the N-type semiconductor region (base) of the diffusion resistor 25, and the P-type semiconductor substrate (collector). Connection points 27 to 29 between each phase of the motor and the semiconductor device for driving the magnetic disk motor (FIG.
(See FIG. 2), the parasitic NPN transistor 30 is turned on, supplies the base current of the parasitic PNP transistor 31, and the parasitic PNP transistor 31 is turned on. The parasitic current 32 flows toward the (collector). As described above, the magnetic disk motor driving semiconductor device normally controls the head actuator driving circuit even after the power supply voltage is cut off, in order to realize the function of moving the head actuator 3 to the retracted position when the power supply voltage is cut off. There is a need to. However, since the parasitic current 32 is a current flowing from the inside of the head actuator control circuit 5 (diffusion resistor 25) to the P-type semiconductor substrate, it causes a malfunction of the head actuator control circuit 5 when the power supply voltage is cut off.

An example of a malfunction will be described with reference to FIG. Since the diffusion resistor 50 corresponds to the diffusion resistor 25 shown in FIG. 4, as described above, the parasitic NPN transistor 3
0 (see FIG. 4) and the parasitic PNP transistor 31 (see FIG. 4) are generated, and the diffusion resistance 25 (the diffusion resistance 50 in FIG. 6) is generated.
, A parasitic current flows toward the P-type semiconductor substrate. As a result, the residual charge of the external capacitor 38 is consumed as a parasitic current flowing from the diffusion resistor 50 to the substrate, and it becomes impossible to supply a current necessary for the operation of the head actuator 3.

As described above, the residual charge of the external capacitor 38 is no longer held by the parasitic current of the diffusion resistor 50, so that the gate bias of the DMOS transistors of S7 and S9 cannot be performed, and the head when the power supply voltage is cut off. The actuator control circuit will malfunction.

The collector of the parasitic NPN transistor 30 includes not only the N-type semiconductor region of the diffusion resistor 25 described above but also an N-type epitaxial layer region where no circuit element is present as an emitter, a P-type semiconductor substrate as a base, The emitter current of the parasitic NPN transistor 33 having the N-type semiconductor region of the other circuit as a collector is supplied to turn on the parasitic NPN transistor 33, thereby turning off the N-type semiconductor region (collector) of the head actuator control circuit 5 when the power is cut off. A parasitic current 34 flows toward the N-type semiconductor region (emitter) where no element is formed, and this parasitic current also causes the head actuator control circuit 5 to malfunction.

As described above, in the magnetic disk motor driving semiconductor device, a parasitic current flows which causes a malfunction of the head actuator control circuit 5 when the power is turned off. In order to reduce the influence of the parasitic current, the conventional magnetic disk motor driving semiconductor device utilizes the property that the absolute value of the parasitic current is proportional to the physical distance from the N-type semiconductor region which becomes a negative potential. Then, the head actuator control circuit 5 when the power supply voltage is cut off is arranged on the semiconductor chip at a position where the distance from the ground-side N-channel DMOS transistor is large, or each phase of the motor and the magnetic disk motor drive The negative voltage is clamped by an external circuit so that the parasitic NPN transistor 30 does not occur at the connection point of the semiconductor device.

[0017]

As described above, in the conventional configuration, in order to prevent the malfunction of the head actuator control circuit 5 when the power supply voltage is cut off by the parasitic current 32, the power supply voltage susceptible to the parasitic transistor is required. Either a restriction on the mask layout that the head actuator control circuit 5 at the time of cutoff is physically located at a distance from the N-channel DMOS transistor on the ground side is provided, or each phase of the motor and the semiconductor for driving the motor are provided. It was necessary to attach an external clamp circuit to the connection point of the device.

The present invention solves the above-mentioned conventional problems, and provides a semiconductor device for driving a motor which can reduce the influence of a parasitic transistor without restricting the layout or attaching an external clamp circuit. The purpose is to do.

[0019]

In order to achieve this object, a motor driving semiconductor device according to the present invention has a multi-phase branch composed of two power elements each connected in series. The middle point of the two power elements in each branch is connected to the motor coil, and the power supply side of each branch is obtained by rectifying and extracting the induced electromotive force generated by the inertial rotation of the motor when the power supply voltage is cut off. A common connection point on the power supply side of the branch, a diode having an anode connected to the middle point of the two power elements of each branch and a cathode connected to the common connection point, and a power supply voltage exists. Has a separating device that is in a high conduction state and becomes insulated when the power supply voltage is cut off between the common connection point and the power supply voltage point,
An N-type semiconductor region of a diffusion resistance formed by diffusing a P-type semiconductor into an N-type semiconductor and a region where a circuit element is not formed in the N-type semiconductor region are connected to a common connection point.

According to a second aspect of the present invention, there is provided the motor driving semiconductor device according to the first aspect, wherein the power element is a MOS transistor.

According to a third aspect of the present invention, there is provided a semiconductor device for driving a motor having a plurality of phase branches each including two power elements connected in series, and a midpoint between the two power elements in each branch. The power element is a MOS transistor with a built-in diode with the anode connected to the source and the cathode connected to the drain. Has a separation device between the common connection point and the power supply voltage point, which is in a high conduction state and becomes insulated when the power supply voltage is cut off, by diffusing the P-type semiconductor into the N-type semiconductor. The N-type semiconductor region of the diffusion resistor to be formed and the region where no circuit element is formed in the N-type semiconductor region are connected to the common connection point.

With these configurations, after the power supply voltage is cut off, the N-type semiconductor region of the diffused resistor and the N-type semiconductor region where no element is formed become the node obtained by rectifying and extracting the three-phase induced electromotive force generated by the inertial rotation of the motor. 37, no parasitic current flows in the control circuit of the head actuator when the power supply voltage is cut off, and malfunction can be prevented. In addition, when the power supply voltage is present, the separation device is brought into a high conduction state by a command from the power supply voltage detection circuit. Therefore, the potential of the node 37 becomes substantially equal to the power supply voltage, and There is no adverse effect on the operation of the circuit when it is on.

[0023]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram schematically showing a semiconductor section of a semiconductor device for driving a magnetic disk motor according to an embodiment of the present invention. In FIG.
24 is an N-type semiconductor region of the output transistor, 25 is a diffusion resistor, 26 is an N-type semiconductor region where no element is formed,
These 24-26 are the same as the configuration of the conventional example. 37 is generated by the inertial rotation of the motor when the power supply voltage is cut off.
The node 37 is obtained by rectifying and inducing the induced electromotive force of the phase with the DMOS-specific diodes S2, S3, and S6.

The operation of the magnetic disk motor driving semiconductor device according to the present embodiment configured as described above when the power supply voltage is cut off will be described below with reference to FIGS. First, when the power supply voltage is cut off, the power supply voltage detection circuit 6 shown in FIG.
At the same time, the separation DMOS transistor is turned off to cut off conduction between the power supply and the magnetic disk motor driving semiconductor device, and at the same time, the head actuator is driven by the head actuator control circuit 5 via the connection line 9 to move the head to the retracted position. Command to do so. At this time, since the rotation control of the motor by the magnetic disk motor driving semiconductor device is shut off, the voltage of each phase of the motor and the connection points 27 to 29 (see FIG. 3) of the magnetic disk motor driving semiconductor device is changed by the inertial rotation of the motor. Therefore, there is a section where the potential becomes negative. This negative potential is a voltage determined by the unique diodes of S1, S4 and S5. As a result, a parasitic transistor 30 is generated. The parasitic transistor 30 is an N-type semiconductor region (emitter) on the drain side of the N-channel DMOS transistor on the ground, a P-type semiconductor substrate (base), and an N-type semiconductor region (collector) of the diffusion resistor 25, and is a parasitic NPN transistor 30. The parasitic NPN transistor 30 tries to draw the collector current 35 from the N-type semiconductor region of the diffusion resistor 25. However, in the present invention, the N-type semiconductor region of the diffused resistor 25 is connected to the node 37 obtained by rectifying and extracting the three-phase induced electromotive force generated by the inertial rotation of the motor 2. Numeral 35 is generated in the conventional configuration because it is supplied from the induced electromotive force of the motor 2 and the potential of the N-type semiconductor region of the diffusion resistor 25 is the highest potential in the semiconductor device for driving the magnetic disk motor. The parasitic PNP transistor 31 does not turn on, and a parasitic current that causes a malfunction of the head actuator control circuit 5 when the power supply voltage is cut off stops flowing. The collector of the parasitic transistor 30 tries to draw the collector current 36 from a region where no circuit element is formed in the N-type epitaxial layer region. The collector current 36 is supplied from the induced electromotive force of the motor 2 because it is connected to the node 37 that rectifies and extracts the three-phase induced electromotive force generated by the inertial rotation of the motor 2.
In addition, since the N-type semiconductor region has the highest potential in the semiconductor device for driving the magnetic disk motor, the parasitic NPN transistor 33 generated in the conventional configuration is not turned on, and the head actuator control circuit at the time of power-off is turned off. The parasitic current 34 causing the malfunction of No. 5 stops flowing.

As described above, according to the present embodiment, the region where no circuit element is formed in the N-type semiconductor region and the N-type epitaxial layer region of the diffusion resistor 25 is formed by the three-phases generated by the inertial rotation of the motor 2 when the power supply voltage is cut off. Is connected to a node 37 obtained by rectifying the induced electromotive force of the motor and supplying the collector current of the parasitic NPN transistor 30 generated when the power supply voltage is cut off from the induced electromotive force of the motor. 31 does not turn on, and it is possible to prevent the generation of the parasitic current 32 which causes the malfunction of the head actuator control circuit 5 when the power supply voltage is cut off.

[0026]

The present invention rectifies the three-phase induced electromotive force generated by the inertial rotation of the motor 2 when the power supply voltage is cut off in the N-type semiconductor region of the diffusion resistor 25 and the region where no circuit element is formed in the N-type semiconductor region. By connecting to the extracted node 37, the influence of the parasitic transistor generated when the power supply voltage is cut off can be eliminated without connecting an external clamp circuit to each of the connection points 27 to 29 of each phase of the motor 2 and the motor driving semiconductor device. An object of the present invention is to realize an excellent motor drive semiconductor device that can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a semiconductor cross section of a semiconductor device for driving a magnetic disk motor according to an embodiment of the present invention.

FIG. 2 is a block diagram of a semiconductor device for driving a magnetic disk motor.

FIG. 3 is a diagram showing a connection between a motor of a motor device and a semiconductor device for driving a magnetic disk motor.

FIG. 4 is a diagram schematically showing a semiconductor cross section of a conventional semiconductor device for driving a magnetic disk motor.

FIG. 5 is a diagram showing a voltage waveform at a connection point between each phase of the motor and the semiconductor device for driving the magnetic disk motor after the power supply voltage is cut off.

FIG. 6 is a diagram showing an example of a head actuator control circuit when the power supply voltage is cut off.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Power supply line 2 Motor 3 Head actuator 4 Motor control circuit 5 Head actuator control circuit 6 Power supply voltage detection circuit 7 Amplifier 8 Input terminal 9 Connection line 11 Transistor 12 Amplifier 13 Input terminal 14 Connection line 15 Connection line 16 Connection line 17 Connection line 18 Connection line 19 Connection line 20 Connection line 21 Connection line 22 Connection line 23 Connection line 24 N-type semiconductor region 25 Diffusion resistor 26 N-type semiconductor region where no element is formed 27 Connection point 28 Connection point 29 Connection point 30 Parasitic NPN transistor 31 Parasitic PNP Transistor 32 Parasitic current 33 Parasitic NPN transistor 34 Parasitic current 35 Collector current 36 Collector current 37 Node (common connection point on the power supply side of branches 27, 28 and 29) 38 Capacitance 39 Transistor 40 transistor 41 transistor 42 transistor 43 diffusion resistance 44 resistance 45 resistance 46 path 48 diode 49 diode 50 diffusion resistance 52 diode 53 diode 56 diode N branch P branch S1 power element S2 power element S3 power element S4 power element S5 power element S6 power Element S7 Power element S8 Power element S9 Power element S10 Power element U branch V branch W branch

Claims (3)

[Claims] 1. A multi-phase branch comprising two power elements each connected in series, a midpoint of the two power elements in each branch being connected to a motor coil, and a power supply in each branch. Are connected in common to the common connection point on the power supply side of the multi-phase branch obtained by rectifying and extracting the induced electromotive force of the plurality of phases generated by the inertial rotation of the motor when the power supply voltage is cut off, and the anode is the two powers of each branch. A separation element having a diode connected to the middle point of the element and having a cathode connected to the common connection point, which is in a high conduction state when a power supply voltage is present and is in an insulated state when the power supply voltage is cut off. A device is provided between the common connection point and the power supply voltage point, and a circuit element is not formed by an N-type semiconductor region and an N-type semiconductor region of a diffusion resistor formed by diffusing a P-type semiconductor into an N-type semiconductor. Area to the common connection point It continued the motor driving semiconductor device. 2. The motor driving semiconductor device according to claim 1, wherein said power element is a MOS transistor. 3. A multi-phase branch comprising two power elements each connected in series, wherein the midpoint of the two power elements in each branch is connected to the motor coil, and The power supply side is commonly connected at the common connection point, and the power element is a MOS transistor having a built-in diode having an anode connected to a source and a cathode connected to a drain, and in a high conduction state when a power supply voltage is present. A diffusion resistor formed between the common connection point and the power supply voltage point by diffusing a P-type semiconductor into an N-type semiconductor; A motor driving semiconductor device in which an N-type semiconductor region and a region where no circuit element is formed in the N-type semiconductor region are connected to the common connection point.