JP2001025276A - Motor drive control device - Google Patents

Abstract

(57) [Problem] To provide a motor drive control device in which the use efficiency of a power supply voltage is improved while simplifying. SOLUTION: One of first and second output transistors for supplying a voltage or a ground potential of a circuit to a coil of a motor is operated in a pseudo saturation or saturation region, and an output operating in a saturation region is provided. By using the voltage between the collector and the emitter of the transistor as a drive current detection signal for the motor for controlling the rotation speed, there is no need to provide a special current detection element, and the remaining voltage becomes only the saturation voltage of the output transistor and the current detection. There is no need for a resistor element for use and an external terminal for connecting the resistor element, which simplifies the operation and increases the efficiency of use of the power supply voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moke drive control device and, more particularly, to a technology effective for use in a motor drive control device used for a floppy disk drive or a hard disk drive.

[0002]

2. Description of the Related Art In a floppy disk drive or a hard disk drive, a control circuit for a motor for rotating a disk as a storage medium is disclosed in Japanese Patent Application Laid-Open No. 63-294.
290 publication. This publication describes a method of switching the energization of a motor coil in the above-described motor control circuit. For example, in a floppy disk drive or a hard disk drive device, the rotational speed of a motor for rotating a disk as a storage medium is detected by a speed generator or the like, and based on this detection, the speed is compared with a reference clock, and the error signal is transmitted as a control signal. The motor is driven, the drive current is detected by a resistor, and feedback is performed to stabilize the speed.

[0003]

FIG. 7 shows an example of a conventional motor drive circuit. The drive current output from each output transistor is caused to flow through the detection resistor Rfn. By detecting the voltage drop of the detection resistor Rfn, current feedback is applied to the output transistor. However, the voltage drop of the detection resistor Rfn becomes an invalid voltage when viewed from the output stage, and reduces the voltage applied to the load. Such an invalid voltage is not really a problem in a system having a relatively high power supply voltage, for example, 12V. However, in a system that operates at a low voltage of 5 V or less corresponding to a reduction in size and weight, battery driving, or the like, the above-described invalid voltage cannot be ignored since the power supply voltage itself becomes small. In other words, in the conventional motor drive control circuit as described above, a motor which operates at a low voltage of 5 V or less is dealt with by using an expensive magnet having a strong magnetic force for the motor so as to compensate for the invalid voltage. Yes, it increases the cost of the motor used.

[0004] It is an object of the present invention to provide a motor drive control device that simplifies and increases the efficiency of using a power supply voltage. The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0005]

The following is a brief description of an outline of a typical invention among the inventions disclosed in the present application. That is, the three-phase switching signal
In a motor drive control device for forming a drive current supplied to a coil of a phase spindle motor, one of a first output transistor and a second output transistor for supplying a power supply voltage or a ground potential of a circuit to the coil is set to a pseudo saturation or saturation region. And the collector-emitter voltage of the output transistor operating in the saturation region is used as a drive current detection signal for the motor for controlling the rotational speed.

[0006]

FIG. 1 shows a main circuit diagram of an embodiment of a motor drive control device according to the present invention.
FIG. 1 shows an example of a three-phase spindle motor output circuit configuration and blocks attached thereto. In FIG.
A waveform diagram for explaining the operation is shown.

In FIG. 1, three output circuits DV1 and D1
Among V2 and DV3, a specific circuit is shown as the output circuit DV1 as a representative, and the other output circuits DV2 and DV3 are shown.
3 has the same circuit configuration as the output circuit DV1. That is, the emitter of the transistor Q10 of the output circuit DV1 is shared with the emitters of the similar transistors of the other output circuits DV2 and DV3 to form a three differential amplifier circuit.
Also, the emitter of the transistor Q11 is shared with the emitters of similar transistors of the other output circuits DV2 and DV3 to form a three differential amplifier circuit.

[0008] Rotational position control voltage signal (phase switching signal)
U is a first three-differential amplifying transistor Q10 composed of an NPN transistor constituting the output circuit DV1.
And the base of a second three differential amplifying transistor Q11 composed of a PNP transistor.
The rotational position control voltage signals V and W corresponding to the other output circuits DV2 and DV3 are also configured by the base of the first other three differential amplifying transistors configured by the same NPN transistors and the PNP transistor. It is supplied to the bases of the second other three differential amplifying transistors, respectively.

In the output circuit DV1, the collector current of the transistor Q10 is supplied to the bases of PNP transistors Q12 and Q13. The emitters of transistors Q12 and Q13 are connected to power supply voltage VC
C is supplied. The collector of the transistor Q12 is connected to the emitter of the PNP-type three differential transistor Q11. The collector current of the transistor Q11 is supplied to the base of an NPN output transistor Q14 on the ground potential side of the circuit. The collector current of the transistor Q13 is equal to the NPN on the power supply voltage VCC side.
The output transistor Q15 is supplied to the base of the output transistor Q15. The collector of the output transistor Q15 is connected to the power supply voltage VC.
C is applied. The other output circuits DV2 and DV3 are also configured by the same circuit as the output circuit DV1.

The rotational position control voltage signals U, V and W are three-phase voltages as shown in the waveform diagram of FIG. 2. For example, when the voltage signal U is at a high level, V is at a middle level, and W is at a low level, the output signals are output. In the circuit DV1, the transistor Q1
0 turns on, Q11 turns off, and the transistor Q13 corresponds to the collector current of the transistor Q10.
Is turned on, and the output transistor Q15 is turned on. At this time, the PNP-type three differential transistors (corresponding to Q11 of DV1) of the output circuit DV3 are turned on by the low level of the voltage signal W corresponding to the output circuit DV3, and the transistor Q of the output circuit DV1 is turned on.
The collector current formed at 12 is supplied to the base of the output transistor (corresponding to Q14 of DV1) on the ground potential side of the circuit to be turned on. As a result, the output circuit DV1
A U-phase output current flows through the path of the power supply voltage side transistor Q15-output terminal T1, the coil-coil-output terminal T3-the ground potential side output transistor of the output circuit DV3.

Hereinafter, the rotational position control voltage signals U, V and W
The U-phase, V-phase, and W-phase output currents are formed in accordance with the changes in the high level, the middle level, and the low level as shown in the waveform diagram of FIG. In this embodiment, in order to detect the output currents of the U-phase, V-phase and W-phase as described above, instead of using a conventional resistor, the output transistor Q15 in each of the output circuits DV1 to DV3 is connected to the output transistor Q15. The operating current is set such that the collector current of the output transistor on the ground potential side of the circuit is increased as typified by the output transistor Q14 with respect to the emitter current of the output transistor on the power supply voltage side as typified.

Such a current difference causes the output transistors Q14 and Q15 to be formed in the same size, and the base current of the output transistor Q14 is reduced by the output transistor Q1.
5 may be set to be larger than the base current. In the output circuit DV1, the output transistors Q14 and Q15 are not turned on at the same time, and as described above, any two of the three output circuits DV1 to DV3 are combined on the power supply voltage side. The output transistor and the output transistor on the ground potential side of the circuit are turned on.

As described above, the collector current of the transistor Q14 on the ground potential side (lower side) of the circuit is set to be larger than the emitter current of the transistor Q15 on the power supply voltage VCC side (upper side).
4 Saturation or pseudo-saturation always occurs. As a result,
The low level side voltage of the voltage waveform of each phase of U, V or W is determined by the saturation voltage of the lower output transistor, and becomes a voltage proportional to the output current flowing through the coil.

The saturation voltage VCE of these output-side output transistors, that is, the terminals T1 to T1 to which the coil is connected
By detecting the low-level voltage of No. 3, a substantially constant voltage can be obtained. The amplifier circuit AMP is connected to the detected voltage and the control voltage Vcon of the control system.
By comparing t, feedback is applied to the current source transistor Q16 provided at the emitter of the three differential circuits of the output circuits DV1 to DV3, and control is performed so that a constant current flows through the power transistor. As a result, a system for keeping the rotation speed of the motor constant corresponding to the control voltage Vcont can be obtained.

FIG. 3 is a waveform diagram for explaining another embodiment of the motor drive control device according to the present invention. Although the case where the lower output transistor is saturated is described in the waveform diagram of FIG. 2, this embodiment shows a case where the upper output transistor is saturated. The basic operation is performed in the same manner as in FIG. In this example,
The emitter current of the upper output transistor, as represented by the output transistor Q15, is larger than the collector current of the lower output transistor, as represented by the output transistor Q14, in each of the output circuits DV1 to DV3. Set the operating current. Such a current difference may be obtained by forming the output transistors Q14 and Q15 in the same size and setting the base current of the output transistor Q15 to be larger than the base current of the output transistor Q14.

With the above structure, the upper transistor Q
Since the emitter current of the transistor 15 is set to be larger than the collector current of the transistor Q14, the transistor Q15 always becomes saturated or pseudo-saturated when it is turned on. As described above, the high-level side voltage of the voltage waveform of each phase U, V, and W is determined by the saturation voltage VCE of the upper output transistor, and becomes a voltage proportional to the output current flowing through the coil. By detecting the high-level voltage of each phase with respect to the high-level voltage of the voltage VCE, a substantially constant high-level voltage can be obtained. In the amplifier circuit AMP, the high level voltage and the control voltage Vcont of the control system are used.
And feedback is applied to the output circuit to control the output transistor so that a constant current corresponding to the control voltage Vcont flows through the output transistor.

FIG. 4 is a main circuit diagram of another embodiment of the motor drive control device according to the present invention. In the figure, the operating voltages supplied to the emitters of the PNP transistors Q12 and Q13 constituting the pre-driver stage are determined based on the power supply voltage VCC from the transistors Q12 and Q1.
3 is supplied with a boosted voltage VBST (≧ VCC + VBE) which is higher than the base-emitter voltage VBE. With such a configuration, the remaining voltage of the output voltage is determined only by the saturation voltage between the collector and the emitter of the output transistor Q15 and the like, and the effective voltage of the power supply voltage can be further increased. The operation itself is the same as that shown in FIG. 2 or FIG.

FIG. 5 is a circuit diagram showing an embodiment of an amplifier circuit for generating a rotation control current in the moke drive control device according to the present invention. FIG. 11A shows an example of an amplifier circuit AMP in which the lower output transistor Q14 and the like are subjected to pseudo-saturation or saturation operation. FIG. 10B shows the amplifier circuit AMP and the upper output transistor Q15 and the like. An example of the amplifier circuit AMP in the case of performing pseudo-saturation or saturation operation is shown.

As shown in FIG. 1A, when the lower output transistor Q14 and the like are quasi-saturated or saturated as described above, the lower output transistor Q1 of each phase is operated.
Voltage VU corresponding to the collector-emitter voltage such as 4,
VV or VW is a PNP transistor Q21, Q2
2 and Q23. The emitters and collectors of these transistors Q21, Q22 and Q23 are commonly connected, respectively,
The emitter-collector current paths of Q22 and Q23 are paralleled.

A PN having a control voltage Vcont supplied to its base is connected to the three transistors Q21 to Q23.
A P-type transistor Q20 is provided in a differential form. That is, the emitter of the transistor Q20 is connected to the base of the Darlington-connected transistor Q30, and the emitters of the three transistors Q21 to Q23 are shared and connected to the base of the Darlington-connected transistor Q31. These transistors Q30 and Q3
1 is a differential amplifier circuit. Further, a constant current source circuit is provided between the power supply voltage VCC and the common emitter of the differential transistors Q30 and Q31 to flow an operating current. This constant current source circuit includes a transistor Q24, a constant voltage VB supplied to its base, and an emitter resistor RE. A load resistor RL is provided between the collector of the differential transistor Q31 and the ground potential of the circuit. The voltage generated at the load resistor RL is supplied to the base of the transistor Q16 that determines the operating current of the output circuit.

The amplifying circuit of this embodiment has a P
Low-level voltages of voltages VU to VW are detected by the parallel connection of NP-type transistors Q21 to Q23. With respect to the rotation speed control voltage Vcont, the voltages VU to V
When the low-level voltage of W is low, it means that the saturation voltage of the lower transistor Q14 and the like of the output circuit is low. That is, the fact that the saturation voltage VCE is small means that the drive current flowing through the coil is insufficient.

As a result, the transistors Q21-Q
The current flowing through the resistor 23 increases to increase the voltage drop of the resistor RL. Therefore, the base voltage of the transistor Q16 rises, and the control current Icont flowing to the collector of the transistor Q16 increases. For example, if the phase switching signal U is at a high level, the transistor Q of the output circuit DV1
10 takes the on state, and increases the current flowing into the coil corresponding to the U phase through the path of Q10-Q13-Q15.
At this time, if the phase switching signal W is at the low level, the path of the transistors Q10-Q12 of the output circuit DV1, the three PNP-type differential transistors of the output circuit DV3 (corresponding to Q11), and the lower output transistor (corresponding to Q14). Increases the current flowing out of the coil corresponding to the W phase. As a result, the current flowing through the coil increases, and the rotation speed increases.

Conversely, when the low level voltages of the voltages VU to VW are higher than the rotation speed control voltage Vcont,
This means that the saturation voltage of the lower transistor Q14 and the like of the output circuit is large. That is, a high saturation voltage VCE means that the drive current flowing through the coil is excessive. Therefore, the transistor Q2
The current flowing through 1 to Q23 is reduced, and the voltage drop of the resistor RL is reduced. For this reason, the base voltage of the transistor Q16 decreases, and the control current Icont flowing to the collector of the transistor Q16 decreases. For example, if the phase switching signal U is at a high level, the current flowing into the coil corresponding to the U phase in the path of the transistors Q10-Q13-Q15 of the output circuit DV1 is reduced, and the current flowing out of the coil corresponding to the W phase is also reduced. Let it. As a result,
The current flowing through the coil decreases and the rotation speed decreases. In this way, the rotation speed can be set to a value corresponding to the control voltage Vcont.

In this embodiment, the current detection is performed by operating the output transistor in a pseudo-saturation or saturation region and utilizing the resistance itself between the collector and the emitter. As a result, only the saturation voltage of the output transistor is obtained, and the need for a resistance element for current detection and an external terminal for connecting it is eliminated. Thus, it is possible to obtain a motor drive control device in which the use efficiency of the power supply voltage is improved while simplifying the operation.

The circuit shown in FIG. 3B is basically constructed by reversing the conductivity type of each transistor in FIG. That is, as described above, the upper output transistor Q
When pseudo-saturation or saturation operation is performed on the 15th or the like, the voltage VU, VV or VW corresponding to the collector-emitter voltage of the upper output transistor Q15 or the like of each phase is set to NPN.
To the bases of the transistors Q21, Q22 and Q23. The emitters and collectors of these transistors Q21, Q22 and Q23 are commonly connected, and the emitter-collector current paths of the transistors Q21, Q22 and Q23 are arranged in parallel.

The NP having the base supplied with the control voltage Vcont for the three transistors Q21 to Q23.
An N-type transistor Q20 is provided in a differential form. That is, the emitter of the transistor Q20 is connected to the base of the Darlington-connected transistor Q30, and the emitters of the three transistors Q21 to Q23 are shared and connected to the base of the Darlington-connected transistor Q31. These transistors Q30 and Q3
1 is a differential amplifier circuit. Also, the ground potential VSS of the circuit
A constant current source circuit for flowing an operation current between the common emitter of differential transistors Q30 and Q31 is provided. This constant current source circuit includes a transistor Q24, a constant voltage VB supplied to its base, and an emitter resistor RE. A current mirror circuit comprising PNP transistors Q25 and Q26 is provided between the collector power supply voltage of the differential transistor Q31 and the output current of the current mirror circuit flows through a load resistor RL provided on the ground potential VSS side. To be. The voltage generated at the load resistance RL determines the operating current of the output circuit.
Supplied to 16 bases.

FIG. 6 is an overall block diagram of an embodiment of the motor drive control device according to the present invention. The motor drive control device shown in the figure is directed to a three-phase spindle motor drive circuit system. In the figure, each circuit block constituting a semiconductor integrated circuit device IC indicated by a dotted line is formed on one semiconductor substrate such as single crystal silicon by a known semiconductor integrated circuit manufacturing technique. In the figure, the circles indicate external terminals, and the numbers thereof are terminal numbers.

In the figure, Hu _, Hv _, Hw are Hall elements 54 for magnetically detecting the rotational position of the motor. Rotational position detection signals u, v, w are obtained from each of the Hall elements Hu _, Hv _, Hw, supplied to the AGC-equipped amplifier 11, controlled to a constant amplitude, and transmitted to the matrix circuit 12 at the next stage. From the matrix circuit 12, drive signals for each phase U, V and W are formed.

The output circuit 13 for driving the motor comprises output circuits DV1 to DV3 as shown in FIG. 1 or FIG. 4, and output signals U, V, W corresponding to each phase of the matrix circuit 12. Then, the motor coil 51 is driven. The FG amplifier 16 is an input amplifier that amplifies the frequency generator signal. The frequency generator 52 converts the rotation speed of the motor 51 into a frequency, detects the frequency, and supplies it to the FG amplifier 16. The FG amplifier 16 supplies the output signal to a comparator 17, where the FG signal is digital (binary).
Converted to a signal.

The discrimination circuit 18 divides the frequency of the digitized FG signal, and divides the frequency by a reference clock pulse C.
Receiving K, a speed error is detected. Charge pump circuit 1
Reference numeral 9 denotes a current output of the speed error signal, which is converted into a direct current by the charge pump circuit 19 and transmitted to the control amplifier 21 via the buffer circuit 20. The above charge pump circuit 1
9 is provided with a low-pass filter 53 for smoothing.

Although not particularly limited, the reference clock pulse CK used for detecting the speed error in the discrete circuit 18 uses a clock pulse generated by a control circuit such as a microprocessor CPU. Instead, a reference frequency generation circuit such as a crystal oscillation circuit may be provided in the IC and used.

The speed decrement circuit 18 smoothes the error signal by a charge pump circuit (integrator) 19 and outputs it as a DC voltage. The DC-converted error signal is supplied to the control amplifier 21 through the buffer amplifier 20. The control amplifier 21 receives a voltage of a circuit node to which each coil is connected, that is, a saturation voltage between the collector and the emitter of the lower transistor, and generates a control current for stably rotating the motor as compared with the DC voltage. Form.
This control current is supplied to the output circuit 13 by performing current distribution according to the voltage level of each phase in a three differential circuit. In this way, the control amplifier 21 is controlled by the error signal corresponding to the number of times, and the number of rotations of the motor is stabilized at the target speed set according to the frequency of the reference clock pulse CK and the frequency division ratio in the discrimination circuit 12. Is controlled.

Immediately before the motor 51 starts, that is, when the control signal / CE is in an inactive state (high level),
Each hall output is fixed at the power supply voltage Vcc, and the bias circuit 15 is in an off state. The above control signal / C
When E is activated to a low level, the bias circuit 1
5 is also in an operating state, and a bias current flows through each of the Hall elements Hu, Hv, and Hw. Here, / represents that the low level is the active level. In the drawings, it is represented by an overbar according to the conventional logical notation.

By the operation of the bias circuit 15, the outputs u, v, and w of the Hall elements Hu, Hv, and Hw are respectively baked, but if the AGC capacitor is not sufficiently charged, the charging is performed. Since the Hall amplifier 11 does not operate up to this point, there is no particular limitation. In this embodiment, a predetermined voltage is forcibly supplied to the AGC capacitor by the signal / CE and the control signal / CE is activated to a low level. At the same time, it is devised to operate stably.

With such a configuration, the AGC voltage is charged up by the high level of the control signal / CE in the motor stop state, becomes low level when the motor is started, and the charge up is stopped. The AGC voltage becomes the original AGC voltage corresponding to the output signal, and the Hall amplifier (amplifier) 11 is controlled. For this reason, the hall amplifier 11 immediately operates to form a matrix output corresponding to the hall outputs u, v, w.
Prevents generation of through current in the output circuit.

The functions and effects obtained from the above embodiment are as follows. That is, (1) one of the first and second output transistors for supplying the voltage or the ground potential of the circuit to the coil of the motor is operated in the pseudo-saturation or saturation region, and operates in the saturation region. Output transistor collector
By using the emitter-to-emitter voltage as a drive current detection signal for the motor for controlling the rotation speed, there is no need to provide a special current detection element, and the remaining voltage is only the saturation voltage of the output transistor and the resistance element for current detection. Also, there is no need for external terminals for connecting them.
As a result, it is possible to obtain a motor drive control device in which the efficiency of use of the power supply voltage is increased while simplifying the operation.

(2) When applied to a three-phase spindle motor,
The first and second output transistors are provided in three sets corresponding to the three-phase coils, by a matrix circuit which receives a rotational position detection signal of a three-phase Hall element and forms a three-phase three-phase switching signal. By controlling, it is possible to obtain an effect that a moke drive control device suitable for low-voltage operation of a floppy disk drive or a hard disk drive can be obtained.

(3) The three sets of first and second output transistors are set such that the output transistors provided on the ground potential side of the circuit perform pseudo-saturation or saturation operation, respectively, and the three-phase coil Is supplied to the bases of the PNP transistors in parallel with each other by connecting the emitter and the collector in common, and a predetermined reference voltage is applied to the parallel PNP transistors. By providing the applied PNP transistor in a differential form, it is possible to obtain a logical sum of the detection voltages and to perform a voltage comparison operation for speed control together.

Although the invention made by the inventor has been specifically described based on the embodiment, the invention of the present application is not limited to the embodiment, and various modifications can be made without departing from the gist of the invention. Needless to say. For example, the rotational speed signal may be one that is magnetically detected by a Hall element or one that uses a back electromotive voltage of a motor. In this case, a system is provided in which the back electromotive voltage of the motor is detected, a motor drive signal is generated by the signal processing circuit, and the signal is supplied by the AGC circuit as described above.

According to the present invention, a VTR (video tape recorder), an LBP (laser beam printer), and other PPCs (pre- It can be widely used for various types of motor drive control circuits such as various driver ICs and scanner ICs. The motor may be a two-phase motor in addition to a three-phase motor.

[0041]

The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows. That is, one of the first and second output transistors for supplying the voltage or the ground potential of the circuit to the coil of the motor is operated in a pseudo-saturation or saturation region, and the output transistor operating in the saturation region is operated. By using the collector-emitter voltage as a drive current detection signal for the motor for rotation speed control,
There is no need to provide a special current detection element, and the remaining voltage is only the saturation voltage of the output transistor, and the need for a current detection resistance element and an external terminal for connecting the same is eliminated. Thus, it is possible to obtain a motor drive control device in which the use efficiency of the power supply voltage is improved while simplifying the operation.

[Brief description of the drawings]

FIG. 1 is a main circuit diagram showing one embodiment of a motor drive control device according to the present invention.

FIG. 2 is a waveform chart for explaining an example of the operation of the motor drive control device of FIG. 1;

FIG. 3 is a waveform chart for explaining another example of the operation of the motor drive control device of FIG. 1;

FIG. 4 is a main circuit diagram showing another embodiment of the motor drive control device according to the present invention.

FIG. 5 is a circuit diagram showing an embodiment of an amplifier circuit for generating a rotation control current in the moke drive control device according to the present invention.

FIG. 6 is an overall block diagram showing an embodiment of a motor drive control device according to the present invention.

FIG. 7 is a circuit diagram showing an example of the related art.

[Explanation of symbols]

DV1 to DV3: output circuit, AMP amplifier circuit, Q10
Q26: transistor, RL, R1: resistor, 11: amplifier (Hall amplifier), 12: matrix circuit, 13:
Output circuit, 14 AGC circuit, 15 Bias circuit, 1
6 FG amplifier, 17 comparator circuit, 18 discrete circuit, 19 charge pump circuit, 20 buffer amplifier, 21 control amplifier, 51 motor, 52 frequency generator, 53 low-pass filter, 54 Hall element, IC: semiconductor integrated circuit device, CPU: microprocessor.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yuichi Okubo 5-2-1, Kamimizuhoncho, Kodaira-shi, Tokyo F-term in Hitachi Semiconductor Group 5H560 AA03 AA04 AA05 BB03 BB04 BB07 BB12 DA02 DA13 DA19 DB06 DC12 DC13 EB01 RR10 TT05 TT07 TT08 TT14 TT15 TT18 UA03 XA02 XA03 XA04 XB06

Claims (3)

[Claims] 1. A motor, a first output transistor for supplying a drive current to a coil of the motor in a first direction, and a drive current for a coil of the motor in a second direction opposite to the first direction. And a drive circuit for supplying a control signal corresponding to the rotation operation and rotation speed of the motor to the first and second output transistors. One of the two output transistors is operated in a pseudo-saturation or saturation region, and the collector-emitter voltage of the output transistor operating in the pseudo-saturation or saturation region is used as a drive current detection signal for the motor to control the rotation speed. A motor drive control device characterized by being used for: 2. The motor according to claim 1, wherein the motor is a three-phase spindle motor, and the first and second output transistors are provided in three sets corresponding to three-phase coils. The moke drive control device according to claim 1, wherein the circuit includes a matrices circuit that receives a rotational position detection signal of a Hall element having three phases and generates a three-phase switching signal having three values. 3. The circuit according to claim 2, wherein the first and second output transistors are set so that the output transistors provided on the ground potential side of the circuit perform pseudo-saturation or saturation operation, respectively. The potentials of the circuit nodes to which the three-phase coils are connected are supplied to the bases of the PNP transistors in parallel by connecting the emitter and the collector in common, respectively. A PNP transistor to which the reference voltage is applied is provided in a differential form to form a rotation speed detection current.