JP3438976B2 - Motor drive integrated circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an integrated circuit for driving a motor.

[0002]

2. Description of the Related Art Generally, when driving a three-phase DC brushless motor, a source side transistor and a sink side transistor are connected in series between a power source Vcc and ground, and the source side transistor and the sink side transistor are connected. It is necessary to provide three sets between the power source Vcc and the ground and connect a three-phase drive coil (for example, star connection) to each connection point of the three sets of the source side transistor and the sink side transistor. Then, three control signals (sine wave signal or rectangular wave signal, etc.) having a phase shift of 120 degrees are selectively applied to the control electrodes of any one of the source side transistor and the sink side transistor to apply the three phase signals. The motor is rotationally driven by repeating the operation of continuously supplying the current to the drive coil.

Here, when controlling the rotation of the motor to be a constant rotation, the magnitude of the voltage generated when the drive coil is energized is detected, and the rotation of the motor is controlled based on the detected voltage. The action is performed. Therefore, one of the source-side transistor and the sink-side transistor is driven in a non-saturated state, and the source-side transistor or the sink-side transistor is in a non-saturated state according to the magnitude of the detection voltage. The control of the magnitude of the control signal applied to either one of the control electrodes is controlled to control the amount of current flowing through the drive coil, thereby controlling the rotation of the motor.

[0004]

By the way, when designing an integrated circuit for driving a motor for performing the above operation, the output saturation voltage of either the source side transistor or the sink side transistor driven in a saturation state, In order to satisfy specifications such as maximum output current, the pattern size on the chip of the transistor on the side driven in a saturated state is determined based on the output voltage-output current characteristics of the transistor. When actually performing the printing on the chip using a mask, both the source side transistor and the sink side transistor are printed with the same pattern size as described above.

For example, when the source side transistor is driven in a non-saturated state and the sink side transistor is driven in a saturated state, the ratio of the control signals applied to the source side transistor and the sink side transistor is: Generally, it is about 1: 2. In this case, even if the control signal applied to the control electrode of the source-side transistor is maximized based on the detected voltage in order to keep the rotation of the motor at a constant speed, the source-side transistor will not be saturated.

However, there is no problem in that the source side transistor can always be driven in a non-saturated state, but on the other hand, since the pattern area of the source side transistor is the same as the pattern area of the sink side transistor, the pattern area is printed.
There is a problem in that the pattern area of the source side transistor is too large, resulting in an increase in the chip area of the entire motor driving integrated circuit. In particular, since the source and sink side transistors are the final stage of the motor driving integrated circuit, that is, they must supply a sufficient current to the driving coil to rotate the motor, other transistors inside the motor driving integrated circuit are required. The size is much larger than the transistor size. Therefore, if the source side transistor has a size that is too large to drive in a non-saturated state, the entire chip size of the motor driving integrated circuit becomes extremely large, and it cannot be applied to the motor application in the worst case. There was a fatal flaw that caused it.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a motor driving integrated circuit which can reduce the chip size and which controls the rotation of the motor.

[0008]

The present invention has been made to solve the above problems, and is characterized in that a source-side transistor and a source-side transistor are provided between a first power supply and a second power supply. Sink side transistors are connected in series and a plurality of pairs of the source side transistor and the sink side transistor are provided, and each connection point of the plurality of pairs of the source side transistor and the sink side transistor is connected to a drive coil of a plurality of phases. And driving either one of the source-side transistor and the sink-side transistor in a non-saturated state, and selectively driving the plurality of pairs of source-side transistor and sink-side transistor. In a motor drive integrated circuit for rotationally driving a motor by supplying current to the drive coils of the plurality of phases A control electrode for forming the source side transistor, in that the smaller than the pattern area of each electrode of the sink side transistor pattern area of each electrode of the input electrodes and output electrodes.

[0009]

According to the present invention, in the motor driving integrated circuit for controlling the rotation of the motor by driving either the source side transistor or the sink side transistor in a non-saturated state, the control electrode and the input electrode of the source side transistor , And the pattern area of each electrode of the output electrode can be made smaller than the pattern area of each electrode of the sink-side transistor, and the total chip area can be reduced.

[0010]

The details of the present invention will be described in detail with reference to the drawings. FIG. 1 is an integrated circuit for driving a motor applied to the present invention, in which the configuration excluding the three-phase drive coils is integrated. In FIG. 1, (1U) (1V) (1W) are U-phase, V-phase, and W-phase drive coils that are star-connected, respectively. (2U) (2V) (2W) are source side transistors, the collectors of which are connected to the power supply Vcc. still,
The source side transistors (2U) (2V) (2W) are respectively connected to the transistors (3U) (3V) (3W) in Darlington connection. (4U) (4V) (4W) is a sink side transistor, each collector is connected to the emitter of a source side transistor (2U) (2V) (2W), and each emitter is grounded via a detection resistor (5). ing.
The connection point of the source side transistor (2U) and the sink side transistor (4U), the source side transistor (2U)
V) and the sink side transistor (4V), and the connection point between the source side transistor (2W) and the sink side transistor (4W) are the external terminals (6U) of the integrated circuit.
(6V) (6W) is connected to this external terminal (6
The other ends of the drive coils (1U) (1V) (1W), which are star-connected, are connected to U) (6V) (6W). Also,
(7) is a control circuit, which is a drive coil (1U) (1V)
A control signal for supplying a drive current to (1 W) is generated. Specifically, the source side transistor (2
U) (2V) (3W) Inverted Darlington connection transistors (3U) (3V) are similarly applied by applying three sine wave signals or rectangular wave signals having a phase shift of 120 degrees to the bases of (2V) (2W). Three sine wave signals or rectangular wave signals having a phase shift of 120 degrees are also applied to the (3W) base. As a result, any one of the source side transistors (2U) (2V) (2W) selectively conducts and any one of the sink side transistors (4U) (4V) (4W). Are selectively conducted, and three-phase drive coils (1U) (1
Current will flow through any one of V) (1 W).
Drive coil (1U) by 6 outputs of control circuit (7)
An electric current continues to flow in (1V) and (1W), whereby the motor is driven to rotate.

By the way, transistors (3U) (3V)
(3W) is driven in a non-saturated state, that is, the source side transistors (2U) (2V) (2W) are driven in a non-saturated state, and the sink side transistor (4U).
It is assumed that (4V) and (4W) are driven in a saturated state. Here, the source side transistor (2U) (2V)
The reason for driving (2W) in a non-saturated state is that the output current of the source side transistors (2U) (2V) (2W) is changed according to the output level of the control circuit (7), and the drive coil (1
This is because the rotation speed of the motor is controlled by varying the current flowing through U) (1V) (1W). For example, at a certain timing during rotation of the motor, the source side transistor (2U) and the sink side transistor (4V) are turned on by the output of the control circuit (7), and the drive coil (1U) passes through the drive coil (1V). Assuming that a current flows through the detection resistor (5), the terminal voltage of the detection resistor (5) at this time is fed back to the control circuit (7) and then the transistor (3
The signal level applied to U) (3V) (3W) is controlled. As a result, the drive coil (1U) (1V) (1
The current flowing in W) is controlled to rotate the motor at a constant speed.

Here, as described in the section of the prior art, the source side transistors (2U) (2V) (2W) and the sink side transistors (4U) (4V) (4W) have the same size. That is, first, the size of the sink side transistors (4U) (4V) (4W) driven in the saturation state is determined based on the output current-output voltage characteristics of the transistors while considering the specifications such as the output saturation voltage and the output maximum current. After deciding, this sink side transistor (4U) (4V) (4
W) source side transistor (2U) (2)
V) (2W) is baked on the chip. Further, since the source side transistors (2U) (2V) (2W) are connected to the transistors (3U) (3V) (3W) by inverted Darlington connection, the transistor (3U)
Even if (3 V) and (3 W) are driven in a saturated state according to the state of the motor, the source side transistors (2U) (2
At least a voltage obtained by adding the collector-emitter voltage of the transistors (3U) (3V) (3W) and the base-emitter voltage of the source side transistors (2U) (2V) (2W) between the collector emitters of V) (2W). Will occur. This source side transistor (2U) (2
V) (2 W) collector-emitter voltage tends to decrease for the same output current as the pattern size increases. However, even if the collector-emitter voltage can be reduced, the contradictory problem that the pattern size becomes large occurs.

FIG. 2 is a characteristic diagram showing the relationship between the output current Io of the transistor and the collector-emitter voltage VCE. The characteristic diagram on the rightmost side shows the case where the pattern size is large, and the pattern size becomes smaller toward the left side. The characteristic diagram in the case is shown. As is clear from this characteristic diagram,
It can be seen that the collector-emitter voltage VCE decreases for the same output current Io as the pattern size increases. Therefore, based on this characteristic, an optimum size that does not cause saturation of the source side transistors (2U) (2V) (2W) may be selected and printed on the chip with a mask. Here, the source side transistor (2U) (2V)
(2W) and sink side transistor (4U) (4V)
Since the base input of (4W) is about 1: 2 when the motor is rotating at a constant speed, the size of the source side transistor (2U) (2V) (2W) selected above is the sink side transistor (4U). It is obviously smaller than the size of (4V) (4W). This is shown in FIG. Here, A, B and C indicate the sizes of the source side transistors (2U) (2V) (2W) on the chip, and D, E and F indicate the sink side transistors (4U) (4U).
V) (4W) is shown. Source side transistor (2U) (2V) occupying a large area on the chip
Since the size of (2W) can be reduced, the size of the chip can be greatly reduced.

Contrary to the above embodiment, when the sink side transistors (4U) (4V) (4W) are driven in a non-saturated state and the transistors (3U) (3V) (3W) are driven in a saturated state. , That is, the source side transistor (2
U) (2V) (2W) When the base input is maximized, the source side transistors (2U) (2V) (2
Since the collector-emitter voltage of W) is generated in the same manner as in the above embodiment, the source side transistor (2U) (2V).
The pattern size of (2W) can be made smaller than the conventional one.

[0015]

According to the present invention, one of the source side transistor and the sink side transistor is driven in a non-saturated state, and the motor rotation is controlled by controlling the current of the drive coil. In, the pattern size of the source side transistor can be reduced
The great advantage is that the chip itself can be significantly miniaturized.

[Brief description of drawings]

FIG. 1 is a diagram showing a motor driving integrated circuit to which the present invention is applied.

FIG. 2 is a characteristic diagram showing output current and output voltage characteristics of a transistor.

FIG. 3 is a diagram showing a chip pattern to which the present invention is applied.

[Explanation of symbols]

(1U) (1V) (1W) Drive coil (2U) (2V) (2W) Source side transistor (4U) (4V) (4W) Sink side transistor

Claims (2)

(57) [Claims] 1. A source-side transistor and a sink-side transistor are connected in series between a first power supply and a second power supply, and a plurality of pairs of the source-side transistor and the sink-side transistor are provided, and the plurality of pairs of the sources are provided. A configuration in which each connection point of the side transistor and the sink side transistor is a connection point with a drive coil of a plurality of phases, and either one of the source side transistor and the sink side transistor is driven in a non-saturated state, In a motor driving integrated circuit that drives a motor to rotate by selectively driving the plurality of pairs of source side transistors and the sink side transistors to supply current to the plurality of phase drive coils, the source side transistors are Set the pattern area of each control electrode, input electrode, and output electrode to be formed. Motor driving integrated circuit, characterized in that the smaller than the pattern area of each electrode of the serial sink side transistor. 2. The motor driving integrated circuit according to claim 1, wherein the source side transistor has a transistor connected in inverted Darlington connection in a preceding stage thereof.