JP2803354B2 - Motor drive integrated circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor driving integrated circuit, and more particularly to a motor driving integrated circuit for driving a stepping motor used in a floppy disk drive.

[Prior Art] Conventionally, as shown in FIG. 3, a motor driving integrated circuit of this type includes an H bridge circuit 100 composed of four MOS transistors 11 to 14 connected to input terminals 1 and 2. The power is controlled by a signal, and at the time of power saving, the gate voltages of the P-type MOS transistors 11 and 13 become the output voltage (normally 2.4 V) of the reference voltage generation circuit 10 and operate so as to control the current supplied to the motor. The switching of the gate signal is P-type and N-type.
This is performed through switches 3 and 4 each formed of a MOS transistor of a type. The switching signal of the switch is
The two signals of the power save signal input terminal 2 and the output H-bridge signal input terminal 1 are synchronized by the 0 and NAND circuits 17 and 18. The conventional motor drive circuit includes a normal operation for turning on a first MOS transistor 11 and a fourth MOS transistor 14, a reverse operation for turning on a second MOS transistor 12 and a third MOS transistor 13, and four MOS transistors. And a stop operation for turning off all the transistors 11 to 14, and the power save mode operates during the normal rotation operation and the reverse rotation operation.

[Problems to be Solved by the Invention] In the above-described conventional motor drive circuit, the current setting at the time of power saving is performed by the output voltage of the reference voltage generation circuit 10, so that the bandgap reference circuit is less dependent on the power supply voltage and temperature. Is used, accurate current setting becomes possible. However, depending on the type of motor, it is necessary to change the set current at the time of power saving, and there is a problem that changing the set current requires a significant change inside the integrated circuit. Therefore, there has been a demand for a motor driving integrated circuit that is less dependent on the power supply voltage and temperature change and that can easily change the current during power saving externally.

Means for Solving the Problems The gist of the first invention of the present application is that a reference voltage generating circuit for generating a first control voltage and a second control supplied from outside in response to an operation mode signal supplied from outside. A switch circuit that outputs a voltage or a first control voltage, and an H-type bridge circuit that controls the polarity and current value of a drive current supplied to the motor in response to the first control voltage or the second control voltage supplied from the switch circuit In the integrated circuit for driving a motor, the external terminal to which a resistor having an arbitrary resistance value is connected, the positive-phase input terminal is connected to the external terminal, and the negative-phase input terminal is connected to the reference voltage generating circuit, respectively. Operational amplifier,
A series circuit of a transistor constituting an H-type bridge circuit, a current mirror transistor constituting a current mirror, and a voltage control transistor connected to an output terminal of an operational amplifier are connected in series between a power supply terminal and an external terminal. The first control voltage is generated at an intermediate node between the current mirror transistor and the voltage control transistor.

The gist of the second invention of the present application is a motor driving integrated circuit that drives a motor by controlling a current flowing through an H-type bridge circuit based on a signal input from the outside, wherein a resistance connection terminal and a voltage of the resistance connection terminal are fixed. The present invention has a constant voltage circuit for controlling a voltage, and a current mirror circuit for flowing a current proportional to a current flowing to a resistor connected to the resistor connection terminal to an H-type bridge circuit.

[Operation of the Invention] When the operation mode signal specifies the normal mode, the switch circuit supplies the second control voltage to the first predetermined node or the second predetermined node of the H-type bridge circuit to change the rotation direction and the rotation direction of the motor. The H-type bridge circuit controls the rotation speed.

When the operation mode signal specifies the power save mode, the switch circuit supplies the first control voltage to the first or second predetermined node of the H-bridge circuit, and determines the rotation direction and the rotation speed of the motor in the H-bridge circuit. Control.

The first control voltage is determined by the value of the current flowing through the resistor, and the operational amplifier controls the voltage of the external terminal to match the output voltage of the reference voltage generation circuit. Therefore, the first control voltage can be changed by the resistance value of the resistor.

[Example] Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing a first embodiment of the present invention. As shown in FIG. 1, the difference between the first embodiment and the conventional example shown in FIG. 3 is that a P-type MOS transistor 26, an N-type MOS transistor 27 and an operational amplifier 29 are added, and an external resistor is added.
That is, the current determined by 30 is caused to flow to the output H-bridge circuit 100. More specifically, since the operational amplifier 29 generates the same voltage as the output voltage 31 of the reference voltage generating circuit at the resistor external terminal 28, the voltage is applied to the external resistor 30.
The current of the value divided by the above flows through the two MOS transistors 26 and 27. FIG. 4 shows the relationship between the resistance value of the external resistor 30 and the current value of the current set as a result. A wide current can be set by changing the resistance value. Since the P-type MOS transistor 26 and the MOS transistors 11 and 13 of the output H-bridge circuit 100 constitute a current mirror, a current proportional to the reference current can flow to the output H-bridge circuit 100. An output control signal of the H-bridge circuit 100 is input from an input terminal 1 and forms a two-phase signal through an inverter 9.
Through the output of the H-bridge circuit 100 MOS transistor
The internal input terminals 32 and 33 for driving the transistors 11 and 13 and the internal input terminals 22 and 24 for driving the lower transistors are supplied. The internal input terminals 32, 33, 25 are connected to the internal input terminals 21, 23 via the switches 3, 4, respectively. Signals for driving the switches are controlled by synchronizing two signals of a power save signal input terminal 2 and an output H-bridge signal input terminal 1 by inverters 19 and 20 and NAND circuits 17 and 18.

The MOS transistor 26 constitutes a current mirror transistor, and the MOS transistor 27 constitutes a voltage control transistor. The H-bridge signal which outputs the power save signal functions as the operation mode signal and the second control voltage, respectively.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention. This circuit is an example in which the MOS transistors 11 'to 14' constituting the output H-bridge circuit 200 and the MOS transistor 26 'for setting the reference current use double diffusion type MOS transistors. Similar effects can be obtained by using MOS transistors.

[Effects of the Invention] As described above, the semiconductor device according to the present invention can reduce the current flowing through the output H-bridge circuit by adding two MOS transistors, an operational amplifier, and an external resistor to the conventional semiconductor device. Can be changed by the resistance value. The current flowing through the output H-bridge circuit can be reduced in power supply voltage dependency and temperature dependency by a feedback circuit using an operational amplifier, a H-bridge circuit and a circuit forming a current mirror.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing a first embodiment of the present invention, FIG. 2 is a circuit diagram showing a second embodiment of the present invention, FIG. FIG. 4 is a graph showing the relationship between the resistance value of the external resistor and the output current. 1,2 ... input terminal, 3,4 ... switching MOS switch, 5 ... power supply terminal, 6 ... ground terminal, 7-9 ... inverter, 10 ... reference voltage generation circuit, 11-14 ... MOS Transistors, 11 'to 14' ... Double diffusion type MOS transistors, 15,16 ... Output terminals, 17,18 ... Nand circuit, 19,20 ... Inverters, 21 to 25 ... Internal input terminals, 26, 27 …… MOS transistor, 26 ′… Double diffusion type MOS transistor, 28 …… External resistor terminal, 29 …… Op amp, 30 …… External resistor, 31 …… Op amp input terminal, 100,200… H bridge circuit .

Claims (2)

(57) [Claims] A reference voltage generating circuit for generating a first control voltage; a switch circuit for outputting a second control voltage or a first control voltage supplied from outside in response to an operation mode signal supplied from outside; An H-type bridge circuit for controlling the polarity and current value of a drive current supplied to the motor in response to the first control voltage or the second control voltage supplied from the switch circuit; An external terminal to which a resistor having a resistance value is connected; an operational amplifier having a positive-phase input terminal connected to the external terminal; a negative-phase input terminal connected to the reference voltage generating circuit; a power supply terminal and an external terminal And a voltage control transistor connected to the output terminal of the operational amplifier and the current mirror transistor forming the current mirror and the constituent transistor of the H-type bridge circuit. And a series circuit of a Njisuta, current mirror transistor and a voltage motor driving integrated circuit, characterized in that the intermediate node so as to generate the first control voltage of the control transistor. 2. A motor driving integrated circuit for controlling a current flowing through an H-type bridge circuit based on a signal input from the outside and driving a motor, wherein a resistor connection terminal and a voltage at the resistor connection terminal are controlled to a constant voltage. And a current mirror circuit for causing a current proportional to a current flowing through a resistor connected to the resistor connection terminal to flow through an H-type bridge circuit.