A direct current brush motor bidirectional precise speed regulation driving control circuit

Abstract

The application discloses a bidirectional precise speed regulation driving control circuit for a direct-current brush motor, which comprises a first optocoupler, a second optocoupler, a third optocoupler, a fourth optocoupler, a first MOS tube, a second MOS tube, a third MOS tube, a fourth MOS tube, a first triode, a second triode, a third triode, a fourth triode, a fifth triode, a sixth triode, a first diode, a second diode, a third diode, a fourth diode, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor and an eleventh resistor; the bidirectional precise speed regulation driving control circuit has the advantages that the cost is relatively low, the freewheeling capability is relatively strong, the reliability is relatively high, the control precision is relatively high, the circuit structure is relatively simple, and the area is relatively small.

Description

Technical Field

[0001] This invention relates to a DC brushed motor drive control circuit, and more particularly to a DC brushed motor bidirectional precision speed regulation drive control circuit. Background Technology

[0002] In products such as medical DR systems, there are numerous applications that use DC brushed motors of varying power to drive and control the movement position and speed of components. Currently, the main drive control schemes for DC brushed motors include those based on relay commutation and MOS speed regulation, and those based on dedicated drive control chips. Schemes based on relay commutation and MOS speed regulation are less expensive, but they suffer from low control accuracy, weak current carrying capacity leading to low reliability, and complex circuit structures with larger footprints. Schemes based on dedicated drive control chips offer stronger current carrying capacity, higher reliability, higher control accuracy, relatively simpler circuit structures, and smaller footprints, but they are more expensive. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a bidirectional precision speed regulation drive control circuit for a DC brushed motor that has a low cost, strong follow current capability, high reliability, high control precision, relatively simple circuit structure, and small area.

[0004] The technical solution adopted by this invention to solve the above-mentioned technical problems is as follows: a bidirectional precision speed regulation drive control circuit for a DC brushed motor, comprising a first optocoupler, a second optocoupler, a third optocoupler, a fourth optocoupler, a first MOSFET, a second MOSFET, a third MOSFET, a fourth MOSFET, a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, a sixth transistor, a first diode, a second diode, a third diode, a fourth diode, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, and an eleventh resistor. The first MOSFET and the third MOSFET are both PMOS transistors, and the second MOSFET and the third MOSFET... All four MOSFETs are NMOS transistors. The first, second, fifth, and sixth transistors are NPN transistors, and the third and fourth transistors are PNP transistors. The first, second, third, and fourth diodes are all light-emitting diodes (LEDs). The anode of the first optocoupler is connected to one end of the fifth resistor. One end of the fifth resistor is the first input terminal of the bidirectional precision speed control drive circuit for the DC brushed motor, used to input the voltage control signal CD+ to control the DC brushed motor's movement direction to be positive. The cathode of the first optocoupler is grounded, and the collector of the first optocoupler is connected to the first... The collector of a transistor is connected to a voltage HVD. The emitter of the first optocoupler is connected to the base of the first transistor. The emitter of the first transistor, one end of the fourth resistor, the gate of the first MOSFET, and the cathode of the first diode are connected. The other end of the fourth resistor is connected to a voltage HVC. The anode of the first diode is connected to one end of the third resistor. The other end of the third resistor, the source of the first MOSFET, the source of the third MOSFET, and one end of the eighth resistor are connected, with their connection terminals connected to a voltage HVD. The other end of the eighth resistor is connected to the anode of the third diode. The cathode of the third diode, the... The gate of the three MOSFETs, one end of the ninth resistor, and the emitter of the sixth transistor are connected. The other end of the ninth resistor is connected to voltage HVC. The collector of the sixth transistor is connected to the collector of the third optocoupler, and its connection terminal is connected to voltage HVD. The base of the sixth transistor is connected to the emitter of the third optocoupler. The anode of the third optocoupler is connected to one end of the tenth resistor. The other end of the tenth resistor is the second input terminal of the bidirectional precision speed control drive circuit for the DC brushed motor, used to input the voltage control signal CD- that controls the DC brushed motor to move in the opposite direction. The cathode of the third optocoupler is grounded. The anode of the second optocoupler is connected to one end of the seventh resistor.The other end of the seventh resistor is the third input terminal of the bidirectional precision speed control drive circuit for the DC brushed motor, used to input the control signal CS+ to control the forward speed of the DC brushed motor. CS+ is a PWM signal, and the duty cycle of CS+ determines the forward speed of the DC brushed motor; the larger the duty cycle of CS+, the greater the forward speed of the DC brushed motor. The cathode of the second optocoupler is grounded, the collector of the second optocoupler is connected to the collector of the fifth transistor, and their connection terminal is connected to voltage HVC. The emitter of the second optocoupler is connected to the anode of the second diode. The cathode of the second diode, the base of the fifth transistor, the base of the fourth transistor, and the... One end of the sixth resistor is connected, and the other end of the sixth resistor is connected to the collector of the fourth transistor, with its connection terminal connected to voltage HND. The emitter of the fifth transistor, the emitter of the fourth transistor, and the gate of the second MOSFET are connected. The drain of the second MOSFET and the drain of the third MOSFET are connected, and their connection terminal is the second output terminal of the bidirectional precise speed control drive control circuit for the DC brushed motor. The second output terminal of the bidirectional precise speed control drive control circuit for the DC brushed motor is used to connect to the negative voltage terminal of the DC brushed motor and is used to output a voltage signal M- to control the reverse speed of the DC brushed motor. The drain of the first MOSFET and the drain of the fourth MOSFET are connected and Its connection terminal is the first output terminal of the bidirectional precision speed control drive control circuit for the DC brushed motor. The first output terminal of the bidirectional precision speed control drive control circuit for the DC brushed motor is used to connect to the positive voltage terminal of the DC brushed motor and is used to output a voltage signal M+ to control the forward speed of the DC brushed motor. The source of the second MOSFET, one end of the first resistor, and the source of the fourth MOSFET are connected. The other end of the first resistor is connected to the voltage HND. The gate of the fourth MOSFET, the emitter of the third transistor, and the emitter of the second transistor are connected. The collector of the third transistor is connected to one end of the eleventh resistor, and its connection terminal is connected to the voltage HND. The base, the other end of the eleventh resistor, the base of the second transistor, and the cathode of the fourth diode are connected. The collector of the second transistor is connected to the collector of the fourth optocoupler, and their connection terminals are connected to a voltage HVC. The anode of the fourth diode is connected to the emitter of the fourth optocoupler. The cathode of the fourth optocoupler is grounded. The anode of the fourth optocoupler is connected to one end of the second resistor. The other end of the second resistor is the fourth input terminal of the bidirectional precision speed control drive circuit for the DC brushed motor, used to input the control signal CS- that controls the reverse speed of the DC brushed motor. CS- is a PWM signal, and the duty cycle of CS- determines the magnitude of the reverse speed of the DC brushed motor.The larger the duty cycle, the greater the reverse speed of the brushed DC motor. The voltages HVD and HND are used to provide the normal operating voltage for the bidirectional precision speed control circuit of the brushed DC motor. The voltage HVC is half the value of HVD and is used to provide the on-state voltage drop for the first and third MOSFETs.

[0005] Compared with the prior art, the advantage of this invention lies in the fact that it constructs a circuit diagram of a small-sized, high-current-output-capability bidirectional precise speed regulation drive control circuit for a DC brushed motor by using ordinary optocouplers, resistors, diodes, and transistors. When CD+ is low, the first optocoupler is cut off, the first transistor is cut off, the gate-source voltage drop Vgs of the first MOSFET is 0.5HVD, and the first MOSFET is turned on. When CS+ is high, the first optocoupler is turned on, the fifth transistor is turned on, the gate-source voltage drop Vgs of the fourth MOSFET is 0.5HVD, and the fourth MOSFET is turned on. When CD- is low, the first optocoupler is cut off, the first transistor is cut off, the gate-source voltage drop Vgs of the second MOSFET is 0.5HVD, and the second MOSFET is turned on. When CS- is high, the first optocoupler is turned on, the fifth transistor is turned on, the gate-source voltage drop Vgs of the third MOSFET is 0.5HVD, and the third MOSFET is turned on. When the first and fourth MOSFETs are turned on simultaneously, the voltage between M+ and M- is HVD, driving the DC motor to rotate forward. When the second and third MOSFETs are turned on simultaneously, the voltage between M+ and M- is -HVD, driving the DC motor to rotate in reverse. By adjusting the duty cycle of the four PWM signals CD+, CS+, CD-, and CS-, the speed of forward and reverse rotation of the DC motor can be adjusted. This invention fully utilizes the characteristics of MOSFETs, such as fast switching speed and low on-resistance under saturation conditions, to keep the MOSFETs in a saturated operating state, greatly reducing the component cost of the entire circuit. At the same time, it ensures the control accuracy of the DC motor and minimal power loss when the high-power DC motor is working. Thus, it has a low cost, strong freewheeling capability, high reliability, high control accuracy, relatively simple circuit structure, and small area. Attached Figure Description

[0006] Figure 1 This is a circuit diagram of the bidirectional precision speed control drive circuit for a DC brushed motor according to the present invention. Detailed Implementation

[0007] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0008] Example: Figure 1As shown, a bidirectional precision speed control drive circuit for a DC brushed motor includes a first optocoupler U1, a second optocoupler U2, a third optocoupler U3, a fourth optocoupler U4, a first MOSFET M1, a second MOSFET M2, a third MOSFET M3, a fourth MOSFET M4, a first transistor Q1, a second transistor Q2, a third transistor Q3, a fourth transistor Q4, a fifth transistor Q5, a sixth transistor Q6, a first diode LD1, a second diode LD2, a third diode LD3, a fourth diode LD4, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, and an eleventh resistor. Resistor R11; MOSFETs M1 and M3 are PMOS transistors; MOSFETs M2 and M4 are NMOS transistors; transistors Q1, Q2, Q5, and Q6 are NPN transistors; transistors Q3 and Q4 are PNP transistors; diodes LD1, LD2, LD3, and LD4 are LEDs; the anode of the first optocoupler U1 is connected to one end of the fifth resistor R5, which is the first input terminal of the bidirectional precision speed control drive circuit for the DC brushed motor, used to input the voltage control signal CD+ to control the DC brushed motor's direction of motion in the positive direction. The cathode of the first optocoupler U1 is grounded. The collector of the first optocoupler U1 is connected to the collector of the first transistor Q1, and its connection terminal is connected to voltage HVD. The emitter of the first optocoupler U1 is connected to the base of the first transistor Q1. The emitter of the first transistor Q1, one end of the fourth resistor R4, the gate of the first MOSFET M1, and the cathode of the first diode LD1 are connected. The other end of the fourth resistor R4 is connected to voltage HVC. The anode of the first diode LD1 is connected to one end of the third resistor R3. The other end of the third resistor R3, the source of the first MOSFET M1, the source of the third MOSFET M3, and one end of the eighth resistor R8 are connected, and its connection terminal is connected to voltage HVD. The other end of the eighth resistor R8 is connected to the anode of the third diode LD3. The cathode of diode LD3, the gate of MOSFET M3, one end of resistor R9, and the emitter of transistor Q6 are connected. The other end of resistor R9 is connected to voltage HVC. The collector of transistor Q6 and the collector of optocoupler U3 are connected, and their connection point is connected to voltage HVD. The base of transistor Q6 and the emitter of optocoupler U3 are connected. The anode of optocoupler U3 is connected to one end of resistor R10. The other end of resistor R10 is the second input terminal of the bidirectional precision speed control drive circuit for the DC brushed motor, used to input the voltage control signal CD- that reverses the direction of movement of the DC brushed motor. The cathode of optocoupler U3 is grounded. The anode of optocoupler U2 is connected to one end of resistor R7.The other end of the seventh resistor R7 is the third input terminal of the bidirectional precision speed control drive circuit for the DC brushed motor. It is used to input the control signal CS+, which controls the forward speed of the DC brushed motor. CS+ is a PWM signal, and the duty cycle of CS+ determines the forward speed of the DC brushed motor; the larger the duty cycle, the greater the forward speed. The cathode of the second optocoupler U2 is grounded. The collector of the second optocoupler U2 is connected to the collector of the fifth transistor Q5, and its connection terminal is connected to voltage HVC. The emitter of the second optocoupler U2 is connected to the anode of the second diode LD2. The cathode of the second diode LD2, the base of the fifth transistor Q5, the base of the fourth transistor Q4, and one end of the sixth resistor R6 are connected. The other end of the sixth resistor R6... The collector of the fourth transistor Q4 is connected to the voltage HND. The emitter of the fifth transistor Q5, the emitter of the fourth transistor Q4, and the gate of the second MOSFET M2 are connected. The drain of the second MOSFET M2 and the drain of the third MOSFET M3 are connected, and their connection point is the second output terminal of the bidirectional precision speed control drive control circuit for the DC brushed motor. The second output terminal of the bidirectional precision speed control drive control circuit for the DC brushed motor is used to connect to the negative voltage terminal of the DC brushed motor and is used to output the voltage signal M- to control the reverse speed of the DC brushed motor. The drain of the first MOSFET M1 and the drain of the fourth MOSFET M4 are connected, and their connection point is the first output terminal of the bidirectional precision speed control drive control circuit for the DC brushed motor. The first output terminal of the precision speed control drive circuit is connected to the positive voltage terminal of the DC brushed motor, and is used to output the voltage signal M+ to control the forward speed of the DC brushed motor. The source of the second MOSFET M2, one end of the first resistor R1, and the source of the fourth MOSFET M4 are connected. The other end of the first resistor R1 is connected to the voltage HND. The gate of the fourth MOSFET M4, the emitter of the third transistor Q3, and the emitter of the second transistor Q2 are connected. The collector of the third transistor Q3 is connected to one end of the eleventh resistor R11, and its connection terminal is connected to the voltage HND. The base of the third transistor Q3, the other end of the eleventh resistor R11, the base of the second transistor Q2, and the cathode of the fourth diode LD4 are connected. The collector of the second transistor Q2 and... The collector of the fourth optocoupler U4 is connected to a voltage HVC. The anode of the fourth diode LD4 is connected to the emitter of the fourth optocoupler U4, and the cathode of the fourth optocoupler U4 is grounded. The anode of the fourth optocoupler U4 is connected to one end of the second resistor R2. The other end of the second resistor R2 is the fourth input terminal of the bidirectional precision speed control drive circuit for the DC brushed motor, used to input the control signal CS- that controls the reverse speed of the DC brushed motor. CS- is a PWM signal, and the duty cycle of CS- determines the reverse speed of the DC brushed motor; the larger the duty cycle, the greater the reverse speed. Voltages HVD and HND are used to provide the normal operating voltage for the bidirectional precision speed control drive circuit for the DC brushed motor.The voltage HVC is half the size of the voltage HVD, and it is used to provide the on-state voltage drop for the first and third MOSFETs.

[0009] When the DC brushed motor is controlled by the bidirectional precision speed control drive control circuit of the present invention, the first output terminal of the bidirectional precision speed control drive control circuit of the present invention is connected to the positive voltage terminal of the DC brushed motor, and the second output terminal is connected to the negative voltage terminal of the DC brushed motor.

[0010] If it is necessary to control the forward rotation of the DC brushed motor, a voltage control signal CD+ to control the forward rotation direction of the DC brushed motor is connected to the first input terminal of the DC brushed motor bidirectional precision speed control drive circuit. The second input terminal of the DC brushed motor bidirectional precision speed control drive circuit is left floating. The third input terminal of the DC brushed motor bidirectional precision speed control drive circuit is connected to a control signal CS+ to control the forward rotation speed of the DC brushed motor. The fourth input terminal of the DC brushed motor bidirectional precision speed control drive circuit is left floating. At this time, in the DC brushed motor bidirectional precision speed control drive circuit, when CD+ is a low-level signal, the first optocoupler U1 and the first transistor Q1 are not conducting, and the gate and source of the first MOSFET M1 meet the on-state voltage drop (…). In the HVD-HVC configuration, the drain and source of the first MOSFET M1 are turned on, and the first output terminal M+ is connected to HVD. The CS+ terminal is connected to the PWM control signal. When CS+ is a high-level signal, the second optocoupler U2 is turned on, the fifth transistor Q5 is turned on, and the fourth transistor Q4 is not turned on. The gate and source of the second MOSFET M2 meet the on-state voltage drop (HVD-HVC), and the drain and source of the second MOSFET M2 are turned on. The second output terminal M- is connected to HND. The current flows from the positive output terminal M+ to the negative output terminal M- of the DC brushed motor bidirectional precision speed control drive circuit, realizing the forward rotation of the DC brushed motor. The speed regulation function is achieved by controlling the duty cycle of the PWM control signal. The larger the duty cycle, the higher the speed, and the smaller the duty cycle, the lower the speed. When CS+ is a low-level signal, the second optocoupler U2 is not turned on, the fifth transistor Q5 is not turned on, the fourth transistor Q4 is turned on, the gate of the second MOSFET M2 is pulled low, the on-state voltage drop (HVC) between the gate and source of the second MOSFET M2 is not satisfied, the D and S terminals of the second MOSFET M2 are not turned on, and the current path is broken.

[0011] If it is necessary to control the reverse rotation of the DC brushed motor, a voltage control signal CD- to control the reverse movement direction of the DC brushed motor is connected to the second input terminal of the DC brushed motor bidirectional precision speed control drive control circuit. The first input terminal of the DC brushed motor bidirectional precision speed control drive control circuit is left floating. The fourth input terminal of the DC brushed motor bidirectional precision speed control drive control circuit is connected to a control signal CS- to control the reverse movement speed of the DC brushed motor. The third input terminal of the DC brushed motor bidirectional precision speed control drive control circuit is left floating. At this time, in the DC brushed motor bidirectional precision speed control drive control circuit, when CD- is a low-level signal, the third optocoupler U3 and the sixth transistor Q6 are not conducting, and the gate and source of the third MOSFET M3 satisfy the condition... With the on-state voltage drop (HVD-HVC), the drain and source of the third MOSFET M3 are turned on, and the second output terminal M- is connected to HVD; the CS- terminal is connected to the PWM control signal. When CS- is a high-level signal, the fourth optocoupler U4 is turned on, the second transistor Q2 is turned on, and the third transistor Q3 is not turned on. The gate and source of the fourth MOSFET M4 meet the on-state voltage drop (HVC), and the drain and source of the fourth MOSFET M4 are turned on. The first output terminal M+ is connected to HND. The negative output terminal M- of the DC brushed motor bidirectional precision speed regulation drive control circuit flows to the positive output terminal M+, realizing the reverse rotation of the DC brushed motor. The speed regulation function is achieved by controlling the duty cycle of the PWM control signal. The larger the duty cycle, the higher the speed, and the smaller the duty cycle, the lower the speed. When CS- is a low-level signal, the fourth optocoupler U4 is not turned on, the second transistor Q2 is not turned on, the third transistor Q3 is turned on, the gate of the fourth MOSFET M4 is pulled low, the gate and source of the fourth MOSFET M4 do not meet the on-state voltage drop, the drain and source of the fourth MOSFET M4 are not turned on, and the current path is broken.

Claims

1. A bidirectional precision speed control circuit for a DC brushed motor, characterized in that... The device includes a first optocoupler, a second optocoupler, a third optocoupler, a fourth optocoupler, a first MOSFET, a second MOSFET, a third MOSFET, a fourth MOSFET, a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, a sixth transistor, a first diode, a second diode, a third diode, a fourth diode, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, and an eleventh resistor. The first and third MOSFETs are both PMOS transistors, the second and fourth MOSFETs are both NMOS transistors, the first, second, fifth, and sixth transistors are all NPN transistors, the third and fourth transistors are all PNP transistors, and the first, second, third, and fourth diodes are all light-emitting diodes (LEDs). The anode of the first optocoupler is connected to one end of the fifth resistor. One end of the fifth resistor is the first input terminal of the bidirectional precision speed control drive circuit for the DC brushed motor, used to input the voltage control signal CD+ to control the DC brushed motor's movement direction to be positive. The cathode of the first optocoupler is grounded. The collector of the first optocoupler is connected to the collector of the first transistor, and its connection terminal is connected to voltage HVD. The emitter of the first optocoupler is connected to the base of the first transistor. The emitter of the first transistor, one end of the fourth resistor, the gate of the first MOSFET, and the cathode of the first diode are connected. The other end of the fourth resistor is connected to voltage HVC. The anode of the first diode is connected to one end of the third resistor. The other end of the third resistor, the source of the first MOSFET, the source of the third MOSFET, and one end of the eighth resistor are connected, and their connection terminal is connected to voltage HVD. The other end of the eighth resistor is connected to the anode of the third diode. The cathode of the third diode, the gate of the third MOSFET, one end of the ninth resistor, and the emitter of the sixth transistor are connected to the third diode. The connection is as follows: the other end of the ninth resistor is connected to voltage HVC; the collector of the sixth transistor is connected to the collector of the third optocoupler, and their connection terminals are connected to voltage HVD; the base of the sixth transistor is connected to the emitter of the third optocoupler; the anode of the third optocoupler is connected to one end of the tenth resistor; the other end of the tenth resistor is the second input terminal of the bidirectional precision speed control drive control circuit for the DC brushed motor, used to input the voltage control signal CD- that controls the DC brushed motor to move in the opposite direction; the cathode of the third optocoupler is grounded; and the second optocoupler... The anode of the first optocoupler is connected to one end of the seventh resistor, and the other end of the seventh resistor is the third input terminal of the bidirectional precision speed control drive circuit for the DC brushed motor. This input is used to connect the control signal CS+, which is a PWM signal. The duty cycle of CS+ determines the forward speed of the DC brushed motor; a larger CS+ duty cycle results in a larger forward speed. The cathode of the second optocoupler is grounded, and the collector of the second optocoupler is connected to the collector of the fifth transistor, with its connection terminal connected to a voltage HVC.The emitter of the second optocoupler is connected to the anode of the second diode. The cathode of the second diode, the base of the fifth transistor, the base of the fourth transistor, and one end of the sixth resistor are connected. The other end of the sixth resistor is connected to the collector of the fourth transistor, and its connection terminal is connected to voltage HND. The emitters of the fifth transistor and the fourth transistor are connected to the gate of the second MOSFET. The drain of the second MOSFET is connected to the drain of the third MOSFET, and its connection terminal is the second output terminal of the bidirectional precise speed control drive control circuit for the DC brushed motor. The second output terminal of the circuit is used to connect to the negative voltage terminal of the DC brushed motor, and is used to output a voltage signal M- to control the reverse speed of the DC brushed motor. The drains of the first MOSFET and the fourth MOSFET are connected, and their connection terminal is the first output terminal of the DC brushed motor bidirectional precision speed control drive control circuit. The first output terminal of the DC brushed motor bidirectional precision speed control drive control circuit is used to connect to the positive voltage terminal of the DC brushed motor, and is used to output a voltage signal M+ to control the forward speed of the DC brushed motor. The source of the second MOSFET, one end of the first resistor, and the source of the fourth MOSFET are connected, and the other end of the first resistor is connected to voltage HND. The gate of the fourth MOS transistor, the emitter of the third transistor, and the emitter of the second transistor are connected. The collector of the third transistor is connected to one end of the eleventh resistor, and its connection terminal is connected to voltage HND. The base of the third transistor, the other end of the eleventh resistor, the base of the second transistor, and the cathode of the fourth diode are connected. The collector of the second transistor is connected to the collector of the fourth optocoupler, and its connection terminal is connected to voltage HVC. The anode of the fourth diode is connected to the emitter of the fourth optocoupler. The cathode of the fourth optocoupler is grounded. The anode of the fourth optocoupler is connected to one end of the second resistor. The other end of the second resistor is the fourth input terminal of the bidirectional precision speed control drive circuit for the DC brushed motor, used to connect the control signal CS- for controlling the reverse speed of the DC brushed motor. CS- is a PWM signal, and the duty cycle of CS- determines the reverse speed of the DC brushed motor; the larger the duty cycle, the greater the reverse speed. The voltages HVD and HND are used to provide the normal operating voltage for the bidirectional precision speed control drive circuit for the DC brushed motor. The voltage HVC is half the value of the voltage HVD and is used to provide the on-state voltage drop for the first and third MOSFETs.

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